I especially enjoyed the commentary on a few castings and molds that didn't work out, or were a right pain to produce. Your explanations pointed out a number of things to avoid or design around. I've really enjoyed this series. Thanks for making these videos. Cheers!
James, Most of the bad jobs were ones I had been stuck with by other foundries (Greeks bearing gifts). I long ago resolved that any of my dies would be designed with ease of use and good reliable casting production in mind. Fighting for every casting with a bad die is just not on in my mind.... Martin
My poor little brain is going to explode :) Awesome Martin. Thanks for making these videos. There is so much information herein that I will be watching them a few more times. Mark
Mark Tighten your helmet strap my friend no good having brain all around the room 😱.. I can see in my mind how one could possibly construct a die to make a typical speaker cone spoked support frame - no explosion necessary 😊.... Martin
The explanation on why certain molds didn't work out made me for the first time really... understand... something. In a way it's rather rudimentary: the thin sections freeze first. Of course I knew that already, but I maybe didn't keep it in my mind when I considered other things. It explains why we feed the thickest section in a casting. It also explains why we feed from a feeder and not a sprue - a thinner sprue is needed for avoiding air bubbles, but that thinner sprue will inevitably be one of the first things to freeze up. And there's no feeding through solid metal. I can also now see why two thick sections separated by a thinner section absolutely need their own feeders, no two ways about it - that bridge is going to be rock hard while the thick sections are still thirsty for more metal to take up the shrinkage.
Johannes, Two thick sections separated by a thinner one - Ah. Yes, the dreaded "dogbone" problem. In truth though, sometimes (sometimes) you can get away with just the one feeder on one of the thick sections (the bigger one if there is a difference). It depends on how long and how thin the thin section is and how big the one feeder is as well as the size of the unfed thick "end'- It is all to do with conductivity and flow of liquid from the feeder keeping the thin section just liquid enough to allow feed through to the unfed thick area - it is a risky technique though, and needs to be carefully trialed. I do tend to recomend and use the two feeder approach though..... Martin
I found your channel only recently and have been watching you videos 1 or 2 every day with my morning coffee. I found that it is best way to start my day. I read all the comments and for the really informative ones I have created a file folder "Oldfoundryman" where I copy and paste your replies because the information there is priceless. I've been telling my casting buddy's and now they are watching too. Thank you very much for all you do.
Steven, Interesting way to start a day - I like it! You would be a bit busy reading all the comments but when you think that you have read them all how about sending me a copy of that "Oldfoundryman" file - I would not mind it for my records. (you can email me at olfoundryman@gmail .com)Thanks for spreading the word too, it is much appreciated....Martin
@@olfoundryman8418 I would be happy to send it to you, but it will take a while, I am watching them chronologically and I am still 4 years in the past. I try not to watch too many at once because I will not retain the info or at least which video has the info I might need at that time in the future. Hence the files. Thanks Again!
Thanks heaps for sharing your experience. I used to work in a foundry and it was by far the most interesting place I have ever worked. A lot of the machines they ran there were all custom fabricated like you mention. Most of the big ones were hydraulically powered. Some of them were just used mechanical clamping power. It's only now that I'm older and think about it, they had some great engineers and fabricators that built and maintained these custom machines. Would be great to see more of these videos if you have the time. Cheers!
bin, Yes, gravity die work has pretty much always been custom sort of thing - each shop developed its own machines and methods. I note that now mainly Chinese manufacturers are making die holding machines, but sadly many will not allow proper die filling - their tilt casting machines are all wrong! I do hope to do more videos - I sure have the time but not at the moment the health needed to allow me to get on with it.... Martin
So VERY glad to see you posting again. Your experience and professionalism are true treasure chest! Your an inspiration to thousands of us who want to improve and our skills. Thank you. With sincerity: thanks to YOU.
Greg, Thank you for your comment. I am a bit limited in what I can do regarding videos these days as I am just not as young as I once was. The series that you watched here was actually shot about 3 years ago but I have some ideas for less physical but still hopefully useful videos in the near future.... Martin
@@olfoundryman8418: Well I've been watching for a long time and when ever I get bored with all the political talk, it's an election year here in the US, I re-watch a lot of your old videos.
Peter, I have to cut the dies myself as it is just way too expensive to send to a professional CNC tool maker. It takes me a long time to cut a die but then my labour is cheap 😊.... Martin
First class Martin, taking foundrywork to the highest level,I knew you were a skilled foudryman but your knowlege is colossal,thanks for a really interesting informative video. Graham.
Head, You do me greater honour than I deserve. There are practitioners of the "dark arts" of foundry that are way ahead of me - Bob Puhakka for example.... Martin
That modular die was very insightful, this would cut down on the number of tooling parts needed for moulding the variety of geodesic dome hubs we were discussing previously
Jamie, Yes, it would if you can successfully adapt the idea. I think that the methodology is well suited to the type and number of parts that you wish to make its just the tooling that I see as a bit of a problem.... Martin
I like the videos on this project 👍😀 I worked for 30+ years as a machinist/ hydraulic engineer and in the first few minutes you mention that there are no hydraulic valves to push the cilinders , but there are… You have a few options to use valves and best is to use a set up with a relatively small pump and a few accumulators. This way you can make a suitable hydraulic system. This kind of system is used on plastic molding machines. This is ofcoarse not cheap but you can find a lot of used parts and iverhaul them and adept them to your needs. If you want i can give you a principal schematic of such a system wich can be altered to your machine
A small remark is on the fittings that you used on your machine. They look like malleable fittings and they are actually not suitable for hydraulics and can only withstand low hydraulic pressure. This gets worse in the larger diameters.
@@gertjevanpoppel7270 The hydraulic system of this machine has a working pressure of ~50 PSI, or 3.45 BAR. Definitely counts as low pressure in my book.
@@dfross87 Yes 👍 that is definitely low pressure … you have to be careful not to fart next to the machine or it will open or close 🤣. The castings are great 👍
Gertje, I approached the getting and altering of this machine from a point of view of penury! It had been operated by shop air pressure for many many years and I had seen it thus. I was alarmed by how springy air cylinders are particularly in an application like this where dies need some force to first move and are then quite free -you can imagine how everything use to jump around. Also one at times needs to start a die moving very slowly for the first mm or two lest the casting catch and get ripped apart. Air is noisy all that hissing etc! So I resolved to convert the machine to low pressure hydraulic using an old (and therefore cheap) propellor feathering pump. The cylinders are large 250 mm and 200 mm diameter with strokes up to 250mm. You need control values with large ports to handle the required amount of fluid at the low pressure I had in mind. I had none like this and while they may have been available the cost would no doubt rule them out. So I made my own, just 4 way taps really but with about 15 mm diameter ports, even so the machine is a bit slower than I would like. The slow steady and very controllable flow and thus cylinder speed though I greatly appreciate. Much of the pipe work is as I received the machine I added a bit because I added the top cylinder. It is all common galvanized steel water pipe with the usual malleable fittings. Decent hydraulic fittings would have been nice but then my shoestring budget and clearly at just 50 maybe 60 PSI the waterpipe and malleable will survive just fine. Accumulators would have been a nice addition but ones to go with such a low pressure?? I probably would have had to make one and one of a good size too I suspect - I was actually given a couple but they were small and for a 3000 psi system so not of much use to me. It's not the machine that you have to be careful of farting near its the furnace! 😊... Martin PS. thank you for your offer of a schematic but I have had to let the machine go 😰 😱 to another foundry as I can no longer do the work and I wanted my customers to continue the receive castings
Bradley, The dies and most of the cores are grey cast iron. Mild steel can be used and H13 die steel is used for very long life commercial dies (not by me!). Grey iron purchased as con cast bar is in many ways the best material. The whitish coat is a commercial die coat called "14ESS" it is made by Foseco I think it likely to be a fine refractory like alumina, silica or talc (perhaps) plus a little clay with a sodium silicate binder. It is sprayed onto the hot (200 deg C plus) die as a thin water dispersion, it flash dries to form the whitish layer.... Martin
Somewhere in your videos, you made mention of heat treating castings to T-5 state. Is heat treating a topic you could elaborate on, please. I appreciated the interchangeable die’s and coaxial location of the funnel / filter / runner, for conservation of effort.
George, I have been asked before about doing a video on the T5 heat treatment process. I did say that I would try to do one and you have reminded me of that obligation. However I should warn you that to fully explain it I will have to get into some rather esoteric stuff that many will find rather boring - I expect a rather poor retention rate for the video😊 but I will see what I can do in the coming months. (Oh heck I now have a list of videos to do that is quite long and the take so much time each - this last series took nearly 3 months! Not counting the actual shooting which was done 4 years ago!) ... Martin
dfross, Thank you. I guess I have reached the age and state of uselessness that people do not really know what to get me. I did though get some interesting books and some tools I hope to get well enough to use!...Martin
@@olfoundryman8418 I too have reached that age, and I'm tipping I'm a fair bit younger than you! Any news on getting your back fixed? Tell them it's urgent -- you have viewers waiting anxiously for content!
dfross, Ain't old age a crock of crap! My back is not fixable, simply put I belong in the knackers yard. However I have pain mitigation surgery tomorrow week. It may or may not work and even if it does we won't know how well until afterwards - but still, I have to try it. If it works tolerably well it may give me a new lease of life. Lots of "ifs" and "mays". I hope it does something for I have so much stuff in mind to put out.... Martin
@@olfoundryman8418 It's about bloody time! I hope the surgery goes well for you Martin; both to alleviate the pain, and to relieve your frustration at being unable to do what you want to.
@@olfoundryman8418 Well it's after tomorrow week -- why haven't you made us another video yet 🤣? I imagine it's too early to determine how well the operation went, but hopefully you're on the mend at not in too much discomfort post-op.
Another superb video Martin, & it's given me an Idea on how I might be able to cast this dammed WW2 diecast tail light I have been tinkering with for the last year!!!
good afternoon Maartin. great information again, as always. i just landed a considerable casting job. all brass. would you use the same spru prinsipals for brass as aluminium.
russell, Yes, it may well be easier to do fins with high pressure diecasting but you would need the quantity demand to be high in order to cover the cost of the much more expensive pressure die casting die. I do degas any aluminium that I am going to cast into sand moulds but generally I do not degas metal destined to be cast in a gravity die. The much quicker solidification in a gravity die largely prevents gas being a problem. I degas with Argon gas and Iam not too sure what you mean by "degassing stuff" many people use the most useless of substances for this task, washing soda and epsom salts for example either of which will increase gas levels not reduce them.... Martin
Thank u so much for the amazing content. It is invaluable for us novice DIYers. I'm just curious how you get away with doing a direct pour on some of these die casts. I've tried it a few times in both ceramic shell and sand casting but with little success. All be it with rather questionable mix of alloys. Your previous video entitled "possibilities" is a great source of information thank you again
Shannon, You are not wrong in seeing direct pour as a dubious process! I assume that by direct pour you mean top pour. It is bad because it risks turbulence that both generates oxide films and traps air in the casting. Thin is rather a pity for as I am sure you know it is often the easiest way to get metal into a mould. For the casting shown in this video I first tried it without the shell core "funnel" sitting on top of the ceramic foam filter. It was a complete disaster with 5mm diameter bubbles in every casting - due no doubt to the 100 to 125 mm fall of the metal as it filled the die. Use of the funnel and filter broke the fall up into two approximately 50 mm falls and no bubbles were ever found in now about 500 castings. Whilst having metal freefall at all is a bad thing it's all about the height of the fall. Thus I will always advise no fall at all but my experience is that 50 mm is ok but 100 mm is definitely bad and 200 mm catastrophic. So I use direct pour because it is easy and makes die design easy and cheap but I keep the fall height as low as possible - it is cheating I know but in the main it has worked for me. Note though that I use good metal - certified ingot from a reliable supplier. I would not like to try and achieve the same results with unknown junk scrap wrong alloy dirty oxide ridden etc. etc. metal... Martin
Thank you for sharing your experiences, it's truly very informative! I looked up the Dow Corning 3120 RTV Rubber and the useful temp range is only 300 degrees Celcius. I am looking to make molds in an easy way (not to have them machines in steel) to make zinc anodes which are pretty simple in shape, I am just not sure what to make the mold out of. If this rubber could handle the heat t hat would be great, I would 3d print the positive, then pour the rubber around it to have the mold and start pouring zinc. Would love to hear if you have any solutions. Thank you!
making, Yes, 3120 is not really rated high enough to take zinc but for thin work I got about 50 shots before the mould was useless. I also tried another brand of castable silicon (Wacker I think) it looked the same but broke down on the first shot! Zinc anodes tend to be thick so the castable silicon is a no go. I see two possible methods: 1, use a simple metal die - if the shape is simple with no re-entrant angles a die machined from aluminium should do either billet or cast aluminium. 2, Look up Tekcast - they are big in moldable silicon rubbers for spin casting - they even have a rubber that aluminium can be cast into (on a limited basis). Their web site is very informative. My choice would be #1... Good luck... Martin
Martin, @21:30 you say that quick cooling reduces porosity, but on many other occasions you add exothermic powder to keep metal hot in risers for longer?
That's so the feeder stays hot long enough to feed the casting adequately and avoid shrinkage issues in the casting proper (no problem if there is shrinkage in the feeder). Like many situations, it's a bit of a compromise. I vaguely recall Martin saying that he takes more care to de-gas the metal when he is sand casting because of the slower cooling, but he can explain it better than I can.
Vlad, Adding exothermic to the top of the feeder is unlikely to have much if any of an effect on the solidification time of the casting proper so I doubt that it will increase gas in the casting. As dfross suggests the porosity in the feeder will likely increase but as we melt that down again it does not matter. You will note too that I sometimes chill the bottom of a casting as this will - apart from promoting directional solidification - cause the chilled area to solidify much faster hence less (if any) gas and a stronger more ductile finer structure. Further to dfross's comment I rarely degas metal to be gravity die cast the quicker solidification means gas is unlikely to have time to precipitate out of solution even if the hydrogen level is above the amount that solid aluminium can theoretically hold. It simply stays trapped in super saturated solid solution in the aluminium where it does no harm and may in fact add to the metals strength through an alloying effect (solid solution strengthening) For slower to solidify sand cast work though I am a bit serious about trying to degas properly.... Martin
Great vids, lots of good info and small nuanced teaching you only get from time invested. Any chance you have a vid on gravity mould design? I plan on my first attempt at home doing a metal form to make a product Injeed to complement my lil CNC shop, (trying to learn everything does not/should not be milked from solid! )
Brian, No, sorry I do not have a video on gravity die design. In truth I do not consider that I know enough about the subject to do a video on it (I know, I know this does not stop a lot of Utubers publishing but it does stop me!) Die design is an absolutely huge subject and one that unfortunately has more myth and legend than science involved in it. I am not bad on small simple work but anything big and/or complicated and I run away. My "secret" to die design was to remember that a die is not empty - rather it contains air and if the air cannot get out the metal cannot get in. You see the results at things like internal corners where the metal will round out a little rather than fill the corner completely. A quick touch of die spray will fix the problem for a few shots (the air gets out under the metal through the roughness of the die spray) But a better way is to have some sort of joint in the structure of the die. The air will get out through the minute gap of the joint - if necessary shim the joint apart a "thou" or two. Hence as you say dies are best not milled from a complete solid - segmenting often makes machining easier too. I try to design a die so areas likely to trap air are on joint lines. The other secret to making dies for one's own use is to make them oneself as to have others cut a die for you is way, way too expensive. Then you just have to hope that future sales of the parts cast will cover the cost of your time in cutting the die. This was the only way that I could get into gravity die work - I cut the dies and recouped the time later as best I could - it worked fairly well! If you have a specific part come to me again and I will give you an address you can send details too and maybe - maybe - I can help with a design..... Martin
@@olfoundryman8418 ahh, the sign of a man how has been in the trade a long time, long past the "knows just enough to be a danger". respect! I do have 2 what I assume are simple parts in mind, a little advice would go a long way in saving me time/scraping parts!. I would be happy to share infornmation on them. better yet i can provide the CAD model if thats helpfull.
Brian, Come to me at olfoundryman@gmail.com with whatever drawings/models you have and I wil have a look. No guarantees mind you but I will sure have a good look.... Martin
Of all the things that would be a stretch of my knowledge, every time I watch you, I feel that I should give gravity casting a try. What would be a good starter? Just trying lead, zinc, pewter?
Take a look into bullet casting just to give you an idea of simple permanent mold casting. Simple molds and melting pot. Lead alloys are normally used but some people have done zinc as well. Pick the metal that suits your application. Normally bullet molds were made from cast iron but aluminum molds are also used.
Paul, As Rudy suggests you could look at bullet casting, generally I believe for older black powder relic weapons or perhaps a bit more universal the casting of fishing sinkers. All done in lead of course - although these days on environmental grounds lead free materials are being used. For home casting these would likely be tin bismuth alloys -absolutely great to cast as bismuth does not contract on solidification, it actual expands so a 50:50 tin bismuth alloy neither contracts nor expands makes casting a solid product easy but the metals are expensive. You can buy fishing sinker moulds quite readily so it would be an easy starting place and you can melt the lead or tin/bismuth in a tin can (NOT a soldered one)on a gas stove or barbeque. Most of these moulds are designed without (adequate) feeders for the casting so getting a good solid useable casting can be a question of mould and metal temperature plus pouring technique. It often helps to smoke the mould with a sooty flame. Some people do all sorts of very interesting work in the metals you mention into static silicon rubber moulds... Martin
hi martin, thanks for capturing all this on your vids, it is most informative and inspiring. Can you pls list all the sprays and powders you apply on the aluminium molds before and after pouring? Also, is there a reason you did not cast the molds in steel or iron vs aluminium? wojldnt a steel molds be more "durable"? Pls advise, thanks !
Quentin, I spray the hot die with a mold coat called 14ESS, it is made by Foseco. This is an insulating coat that allows the metal to run and fill the die. Also it helps with air removal from the die. It is my most used die coat. On some parts of the die I use a topcoat (i.e. over the 14ESS) of "Release Coat Blue" by ZYP coatings. This is a coat based on boron nitride and is a very good lubricant thus it aids release from the die - it is however rather expensive. I use a paint on dry MoS lubricant on parts of the die that slide against each other. I also use some graphite powder on some parts of the dies and the machine that holds them, again it's for lubrication purposes. Most of my dies are in fact cut from cast iron. It is a better material than mild steel - higher conductivity for a start and it tends to hold the spray better. It is easier (if a bit dirty) to machine than steel would be. Only a few of my dies were ever made from cast aluminium, these are short life dies and even then can only be used where the part being cast does not contract onto the die - an aluminium die might last 500 shots a cast iron one many tens of thousands of shots. Does this answer your question? ... Martin
@@olfoundryman8418 it exhaustively answers the question, thank you very much for the details. As mentioned, your videos are very informative. Please keep going, "drop" all you've got on youtube !
Hello foundryman, could you please show us your own process of the lost PLA Casting if possible? it's what i do mostly at the foundry, i 3d print a Figure (Mostly small Japanese Cartoon Characters) and do a simple PLA Casting but i get lots of Problems and issues, i just keep trying till i get it randomly right, without knowing what's the issue
David, I have never done lost PLA casting! However I have watched many on UT attempt it with varying degrees of (non) success. The mistakes that many make are (to me) obvious. If you can come to me at olfoundryman@gmail.com with photos of results and a description of what you do and what you use to do it I may be able to help. Considering what you are trying to produce 3D printing is not an unreasonable starting point.... Martin
I'm about 12:30 into the video, and a question occurred to me. Are gravity dies ever filled through a filter or does it tend to be directly poured in from either a ladle or the reservoir shown in your tilt setup?
elitearbor, The 4 barrel throttle body shown being cast near the end of this video is poured through a filter. If I was doing larger and thus likely higher work I would make greater use of filters as they are invaluable in slowing metal velocity down, but most of my casting work is low head height and therefore has low metal velocity - filters are not so necessary under these circumstances. I think it might be somewhat difficult to use filters in tilt work, not impossible mind you, just a bit harder to implement... Martin
Thank you for the thorough explanation! It's good to know that filters remain an option even with this kind of casting. I'll have to rewatch the throttle body casting, I forgot about there being a filter involved.
Thank you for another great video! What are your thoughts on stacking or layering of the metal used to construct your die? I'm trying to produce a part that's around 4" tall and I am having trouble finding material large enough to be able to machine a solid die. I think you might be doing something similar on your four barrel die? It looks as if there might be a 0.5" plate bolted to the top side of the die making up the feeder height? or is that just wishful thinking on my part? :)
Jerred, I like to stack material as the mating faces of the "stack" are never an exact molecular fit so even if well machined they provide minute gaps through which air can escape. Gaps that I might add can be increased with some very thin shim if needs be. There is indeed a plate bolted and doweled onto the top of the two side pieces of the die. This had two important advantages - it made it possible to cut the die in two parts i.e. above and then below this joint line as separate and much easier operations than trying to do it in the one solid. Also and even more importantly it allows air to escape and thus the edge of the casting's mounting flange forms well - if the die had been cut in the solid this edge would likely have rounded because of trapped air. I could easily have got material thick enough to make the die in the solid but I deliberately designed the die with this layered structure. I considered that stacking - IF JOINTS ARE CHOSEN WITH CARE AND PURPOSE - is very much a positive but do remember that it is usually necessary to pull the "stack" apart and clean between layers when readying the die for its next run..... Martin
@@olfoundryman8418 Thank you Martin, I hadn't considered using a 'stack up' for releasing trapped air but that totally makes sense. I started watching your videos forever ago and seeing you produce quality castings they inspired me to try and produce some parts I'd like to make. I realized sand casting was not going to be practical for my needs somewhere around your reflector blanks and throttle body videos where you discussed using a aluminum die, I think.. Already having a cnc, I'm attempting to design a die, which is quite a process.. My hat goes to anyone who has done so. Anyway, I'm in the early stages of machining the mold components but if I run into filling issues it's great to know a potential fix.. Thank you once again.
I remember from your four barrel throttle body video you said that you were using a filter not to filter the metal but instead to reduce turbulence. (as close as I can remember) I don't recall seeing you use filters in any of your other videos. Do you think there is any benefit to using a filter in sand castings, or is it not worth the trouble. (easier to use with permanent molds than fragile sand molds)
Check out Martin's series on casting a piston for a 1910 Brush. He uses a ceramic filter in that casting (which was done in sand). Link to part 1: th-cam.com/video/kf2xae2J9HE/w-d-xo.html
Rudy, dfrossis right I do use a filter in the sand casting of a piston. This is a high mould (for me) and with greater mould height comes greater metal velocity and thus the possibility of greater turbulence. Filters are great for slowing metal down, you can get a speed reduction in the metal stream of 3 to 5 times by incorporating a filter into the running system. For this piston we used a filter at the base of the sprue such that the metal had to go through the filter and then into the runner bar - the runner bar was 4 times the cross sectional area of the sprue exit. The filter reduced the metal velocity to a much safer level. I rarely use filters in my sand work because my moulds are quite low and metal velocities are therefore also fairly low. However if I were to use higher moulds I would likely use filters. In the case of the 4 barrel throttle body I top pour the casting and this is to be honest a recipe for disaster as it is a very turbulent way to pour. Initially I did not use a filter and every casting was found to have 3 to 5 mm air bubbles trapped within it and revealed on machining - clearly the result of turbulence from the metal falling straight to the bottom of the casting - a fall distance of a little over 100 mm (4 inches). By using the filter I cut the fall down to two falls of 50 mm (2 inch) each - way less turbulence and in now about 1000 castings no air bubbles.. Filters are fairly cheap at about $0.50 each. While perhaps a bit more difficult to use in sand moulds there are ways of successfully incorporating filters in them. Martin
@@olfoundryman8418 you mean I can machine my own aluminum dies from cast iron! Amazing. Just saved me lots of money. Im trying to cast some pulleys (10 inch/25 cm diameter) out of aluminum and I'm honestly very new to casting anything. This would be of great help. Thanks so much, Martin
Phylis, Yes, you can use grey cast iron to make dies from. In fact it is a rather superior material as it has higher thermal conductivity than most steels and it tends to have a little "roughness" due to the presence of graphite in its microstructure. The graphite being very soft eats out a little and the resulting slightly uneven/rough surface provides excellent keying for the die coats that need to be sprayed on the hot die. Good luck .... Martin
Mat, It is certainly not a stupid question, I have cast thousands of simple aluminium parts into aluminium dies. BUT there are limits - the process does not work with parts that will contract onto the die as this will cause rapid die wear. Die life is short, even with simple parts 200 to 500 castings is about it. But you can make the dies easily quickly and cheaply so it can work well. I have a 4 part video series that shows the whole process from making the masters to cast the die around through making (casting) the die to casting the parts. Here is the link to part 1 of this series th-cam.com/video/hVdLDFAgJBg/w-d-xo.html I cast the die in a piston alloy... Martin
Mat. The boron nitride spray helps because it is a good high temp lubricant but it still will not allow a "contracting on to the die part" to be produced. Whether or not an aluminium die can be used depends very much on part design.... Martin
Andrew, Tesla, yes, a most bold adventure using I think the biggest high pressure diecasting machines ever built - hate to think what the die cost...Martin
Scodiddly, Yes, you are right. The vast majority of heat sinks are extruded and considering the difficulties of casting them I am not surprised. Once you have the extrusion die you can put out miles of the stuff and just cut to length - so much easier and cheaper.... Martin
Been watching your videos... A few things maybe you could go back to the basic for the benefit of the viewer the white powder (ash bones?) You are using and the pro and cons if not as well as the powder you use on the risers and the benefit of it. Thanks. ed
Edouard, Is the white powder that you're referring to the parting agent that I use with my sand moulds? If so it is finely ground Calcium Carbonate. This material is used commercially as a parting agent for green sand moulds and is considered much healthier than using Talcum powder which (possibly) has an asbestos risk. The dark red powder that I use on the feeders is an exothermic called Ferrux NF it is made by Foseco. Its job is to catch fire and generate a lot of heat that keeps the feeders liquid for longer so they are better able to provide feed for the solidifying casting underneath... Martin
small, Yes, it's a pity that we do not have a video of machining one of the many mixers we collectively made - it would have been a nice addition .... Martin
noob, Sadly, no! This whole gravity die video series was filmed way back in August 2019. My health snags still plague me and this is why any recent video releases (with the exception of the "stirring" video) are of material shot some time ago. I am trying to shoot some new stuff, primarily to finish the metal moulding box saga, but it's a question of how much I can get filmed before the pain forces me to sit down and stop - Old age is a crock of crap!....Martin
@@olfoundryman8418 Ugh, sorry to hear that! Sounds like you're between a rock and a hard place, on the one hand looking to 'do something' to keep your mind busy, on the other that something is painful. Maybe do a more theoretical series about alloys and in what cases to use them ? Heat treatment also might be a short topic.I'm sure there's plenty of knowledge that you're glossing over as it's a second nature for you but people have no idea about.
noob, Ugh indeed! "More theoretical" is a road that I do intend to go down, I have several videos in mind including one on heat treatment. However there is a bit of a hump (or two) to get over. I need to create with my hands - I can create with my mind but it just is not as satisfactory, so far I have no way around this disincentive. Often too mind creating requires some hand creation. Then there is the problem with pain and indeed ill health generally in that it grinds you down and seems to rob one of incentive, enthusiasm, and energy - lethargy takes over and little gets done so it's a slow business. Still, one foot in front of the other I guess..... Martin
great video probably one of the most informative videos on casting I have seen. I had learnt so much cheers
jackie, I am glad that you found the video useful.... Martin
I especially enjoyed the commentary on a few castings and molds that didn't work out, or were a right pain to produce. Your explanations pointed out a number of things to avoid or design around. I've really enjoyed this series. Thanks for making these videos. Cheers!
James, Most of the bad jobs were ones I had been stuck with by other foundries (Greeks bearing gifts). I long ago resolved that any of my dies would be designed with ease of use and good reliable casting production in mind. Fighting for every casting with a bad die is just not on in my mind.... Martin
My poor little brain is going to explode :) Awesome Martin. Thanks for making these videos. There is so much information herein that I will be watching them a few more times.
Mark
Mark Tighten your helmet strap my friend no good having brain all around the room 😱.. I can see in my mind how one could possibly construct a die to make a typical speaker cone spoked support frame - no explosion necessary 😊.... Martin
@@olfoundryman8418 We are going to talk Martin. I have but a few ideas.
The explanation on why certain molds didn't work out made me for the first time really... understand... something. In a way it's rather rudimentary: the thin sections freeze first. Of course I knew that already, but I maybe didn't keep it in my mind when I considered other things. It explains why we feed the thickest section in a casting. It also explains why we feed from a feeder and not a sprue - a thinner sprue is needed for avoiding air bubbles, but that thinner sprue will inevitably be one of the first things to freeze up. And there's no feeding through solid metal. I can also now see why two thick sections separated by a thinner section absolutely need their own feeders, no two ways about it - that bridge is going to be rock hard while the thick sections are still thirsty for more metal to take up the shrinkage.
Johannes, Two thick sections separated by a thinner one - Ah. Yes, the dreaded "dogbone" problem. In truth though, sometimes (sometimes) you can get away with just the one feeder on one of the thick sections (the bigger one if there is a difference). It depends on how long and how thin the thin section is and how big the one feeder is as well as the size of the unfed thick "end'- It is all to do with conductivity and flow of liquid from the feeder keeping the thin section just liquid enough to allow feed through to the unfed thick area - it is a risky technique though, and needs to be carefully trialed. I do tend to recomend and use the two feeder approach though..... Martin
You do some great work!
You do some great work as well.
Farm, Thank you - I try (not always successfully 😊).... Martin
lucky, I haven't heard from you for a while - I was beginning to get worried, is all well in your part of this "great" state of ours? ... Martin
@@olfoundryman8418Yep I'm still around in my part of this great state of ours. Hopefully I will upload a video next week.
I found your channel only recently and have been watching you videos 1 or 2 every day with my morning coffee. I found that it is best way to start my day. I read all the comments and for the really informative ones I have created a file folder "Oldfoundryman" where I copy and paste your replies because the information there is priceless. I've been telling my casting buddy's and now they are watching too.
Thank you very much for all you do.
Steven, Interesting way to start a day - I like it! You would be a bit busy reading all the comments but when you think that you have read them all how about sending me a copy of that "Oldfoundryman" file - I would not mind it for my records. (you can email me at
olfoundryman@gmail .com)Thanks for spreading the word too, it is much appreciated....Martin
@@olfoundryman8418 I would be happy to send it to you, but it will take a while, I am watching them chronologically and I am still 4 years in the past. I try not to watch too many at once because I will not retain the info or at least which video has the info I might need at that time in the future. Hence the files. Thanks Again!
Thanks heaps for sharing your experience. I used to work in a foundry and it was by far the most interesting place I have ever worked.
A lot of the machines they ran there were all custom fabricated like you mention. Most of the big ones were hydraulically powered. Some of them were just used mechanical clamping power. It's only now that I'm older and think about it, they had some great engineers and fabricators that built and maintained these custom machines.
Would be great to see more of these videos if you have the time. Cheers!
bin, Yes, gravity die work has pretty much always been custom sort of thing - each shop developed its own machines and methods. I note that now mainly Chinese manufacturers are making die holding machines, but sadly many will not allow proper die filling - their tilt casting machines are all wrong! I do hope to do more videos - I sure have the time but not at the moment the health needed to allow me to get on with it.... Martin
@@olfoundryman8418 Thanks Martin. No rush about any new videos. Take care of your health first. 👍
So VERY glad to see you posting again. Your experience and professionalism are true treasure chest! Your an inspiration to thousands of us who want to improve and our skills. Thank you.
With sincerity: thanks to YOU.
Greg, Thank you for your comment. I am a bit limited in what I can do regarding videos these days as I am just not as young as I once was. The series that you watched here was actually shot about 3 years ago but I have some ideas for less physical but still hopefully useful videos in the near future.... Martin
You are a wonderful artist, with a fantastic style. Your work may not be art, but your process certainly is. Thank you for all the wisdom!
Cyber, Thank you for your comment. Sharing the knowledge is my pleasure... Martin
Thanks for sharing 👍I remember watching you fill this contract 😀
Craig, You have a good memory this footage was shot at least 4 years ago... Martin
@@olfoundryman8418: Well I've been watching for a long time and when ever I get bored with all the political talk, it's an election year here in the US, I re-watch a lot of your old videos.
Very good discussion of die casting as opposed to sand casting... Thanks
Clarke, I guess that is the essence of it - some jobs are sand some are die....Martin
since i started watching your channel i learned a lot about metal casting.
I even build my own furnace
The foundry trade is extremely skilful. Very interesting video series demonstrate some of the required skills, thanks Martin
Gr eg, My plaesure.... Martin
Another interesting video Martin, many thanks.
Jason, Thank you for watching.... Martin
Thank you Martin! Fascinating and inspiring. I enjoyed this immensely.
Kind regards from John Spargo in Cape Town
John, I am glad that you liked it. You have some big foundries over there in Cape Town - I know, I lost work to one of them.... Martin
G'day Martin, excellent series, you make it look so easy. Do you make the dies yourself or send it off to a CNC machinist?
Cheers
Peter
Peter, I have to cut the dies myself as it is just way too expensive to send to a professional CNC tool maker. It takes me a long time to cut a die but then my labour is cheap 😊.... Martin
First class Martin, taking foundrywork to the highest level,I knew you were a skilled foudryman but your knowlege is colossal,thanks for a really interesting informative video.
Graham.
Head, You do me greater honour than I deserve. There are practitioners of the "dark arts" of foundry that are way ahead of me - Bob Puhakka for example.... Martin
Fantastic! Thank you for making these videos mate!
Wikus, No problem.... Martin
That modular die was very insightful, this would cut down on the number of tooling parts needed for moulding the variety of geodesic dome hubs we were discussing previously
Jamie, Yes, it would if you can successfully adapt the idea. I think that the methodology is well suited to the type and number of parts that you wish to make its just the tooling that I see as a bit of a problem.... Martin
Interesting and technical video easily explained by you
sai, Glad that you liked it... Martin
very cool yet again mate! thanks for sharing
JB, Nice to hear from you again, glad that you liked it.... Martin
Very interesting. Thanks for sharing
Rex, Thank you for saying so.... Martin
I like the videos on this project 👍😀
I worked for 30+ years as a machinist/ hydraulic engineer and in the first few minutes you mention that there are no hydraulic valves to push the cilinders , but there are…
You have a few options to use valves and best is to use a set up with a relatively small pump and a few accumulators.
This way you can make a suitable hydraulic system.
This kind of system is used on plastic molding machines.
This is ofcoarse not cheap but you can find a lot of used parts and iverhaul them and adept them to your needs.
If you want i can give you a principal schematic of such a system wich can be altered to your machine
A small remark is on the fittings that you used on your machine.
They look like malleable fittings and they are actually not suitable for hydraulics and can only withstand low hydraulic pressure.
This gets worse in the larger diameters.
@@gertjevanpoppel7270 The hydraulic system of this machine has a working pressure of ~50 PSI, or 3.45 BAR. Definitely counts as low pressure in my book.
@@dfross87
Yes 👍 that is definitely low pressure … you have to be careful not to fart next to the machine or it will open or close 🤣.
The castings are great 👍
Gertje, I approached the getting and altering of this machine from a point of view of penury!
It had been operated by shop air pressure for many many years and I had seen it thus. I was alarmed by how springy air cylinders are particularly in an application like this where dies need some force to first move and are then quite free -you can imagine how everything use to jump around. Also one at times needs to start a die moving very slowly for the first mm or two lest the casting catch and get ripped apart. Air is noisy all that hissing etc! So I resolved to convert the machine to low pressure hydraulic using an old (and therefore cheap) propellor feathering pump. The cylinders are large 250 mm and 200 mm diameter with strokes up to 250mm. You need control values with large ports to handle the required amount of fluid at the low pressure I had in mind. I had none like this and while they may have been available the cost would no doubt rule them out. So I made my own, just 4 way taps really but with about 15 mm diameter ports, even so the machine is a bit slower than I would like. The slow steady and very controllable flow and thus cylinder speed though I greatly appreciate.
Much of the pipe work is as I received the machine I added a bit because I added the top cylinder. It is all common galvanized steel water pipe with the usual malleable fittings. Decent hydraulic fittings would have been nice but then my shoestring budget and clearly at just 50 maybe 60 PSI the waterpipe and malleable will survive just fine.
Accumulators would have been a nice addition but ones to go with such a low pressure?? I probably would have had to make one and one of a good size too I suspect - I was actually given a couple but they were small and for a 3000 psi system so not of much use to me.
It's not the machine that you have to be careful of farting near its the furnace! 😊... Martin
PS. thank you for your offer of a schematic but I have had to let the machine go 😰 😱 to another foundry as I can no longer do the work and I wanted my customers to continue the receive castings
Very much enjoy your content.
Eddie, I am glad that you liked it.... Martin
Loved every part of every video. Thanks for sharing that valuable knowledge with us.
Regards Mark in the UK
thecorbies, Sharing is my pleasure and to have you like it is my reward. Greetings back from Melbourne Australia... Martin
That was a very interesting seroe. I will never do casting, but seeing the techniques used in detail teaches a lot.
Ollivier, Well, never say never because you never know😊 but it you found it interesting I am pleased... Martin
Another great video! I always enjoy watching your videos. I appreciate you Martin.
Sean, Nice to be appreciated, if only more did it 😊.... Martin
Fascinating and interesting
gafrers, Thank you for saying so.... Martin
What a wealth of knowledge. Are the dies and cores all just steel? What's the whitish spray coating applied?
Bradley, The dies and most of the cores are grey cast iron. Mild steel can be used and H13 die steel is used for very long life commercial dies (not by me!). Grey iron purchased as con cast bar is in many ways the best material.
The whitish coat is a commercial die coat called "14ESS" it is made by Foseco I think it likely to be a fine refractory like alumina, silica or talc (perhaps) plus a little clay with a sodium silicate binder. It is sprayed onto the hot (200 deg C plus) die as a thin water dispersion, it flash dries to form the whitish layer.... Martin
Thank you so much for making these videos. They are so interesting to watch.
Brian, I am glad that you found them interesting.... Martin
Thanks for your effort and explanation
Hareth, If the explanation is of use then it's not an effort it's a pleasure.... Martin
Fantastic work as always Martin
Mr Greens, Thank you for saying so.... Martin
Another great video here, Martin!
Mister, I hope that you enjoyed it and that it was useful.... Martin
Fantastic!
Rex, Glad that you liked it... Martin
Really good series, thanks so much for sharing this content. Cheers
Rupert, Thank you for saying so..... Martin
Superb video. Thank you so much for your dedication and great explanations!
Peter, I aim to explain so that others may follow and hopefully improve upon my efforts. I hope that I have inspired you... Martin
Somewhere in your videos, you made mention of heat treating castings to T-5 state.
Is heat treating a topic you could elaborate on, please.
I appreciated the interchangeable die’s and coaxial location of the funnel / filter / runner, for conservation of effort.
George, I have been asked before about doing a video on the T5 heat treatment process. I did say that I would try to do one and you have reminded me of that obligation. However I should warn you that to fully explain it I will have to get into some rather esoteric stuff that many will find rather boring - I expect a rather poor retention rate for the video😊 but I will see what I can do in the coming months. (Oh heck I now have a list of videos to do that is quite long and the take so much time each - this last series took nearly 3 months! Not counting the actual shooting which was done 4 years ago!) ... Martin
Excellent series, thank you!
Sam, Thank you for saying so... Martin
excellent vid thanks
hrxy1, My pleasure.... Martin
Merry Christmas Martin! Hope Santa brought you some nice prezzies.
dfross, Thank you. I guess I have reached the age and state of uselessness that people do not really know what to get me. I did though get some interesting books and some tools I hope to get well enough to use!...Martin
@@olfoundryman8418 I too have reached that age, and I'm tipping I'm a fair bit younger than you!
Any news on getting your back fixed? Tell them it's urgent -- you have viewers waiting anxiously for content!
dfross, Ain't old age a crock of crap! My back is not fixable, simply put I belong in the knackers yard. However I have pain mitigation surgery tomorrow week. It may or may not work and even if it does we won't know how well until afterwards - but still, I have to try it. If it works tolerably well it may give me a new lease of life. Lots of "ifs" and "mays". I hope it does something for I have so much stuff in mind to put out.... Martin
@@olfoundryman8418 It's about bloody time! I hope the surgery goes well for you Martin; both to alleviate the pain, and to relieve your frustration at being unable to do what you want to.
@@olfoundryman8418 Well it's after tomorrow week -- why haven't you made us another video yet 🤣?
I imagine it's too early to determine how well the operation went, but hopefully you're on the mend at not in too much discomfort post-op.
Very enjoyable series. Thanks for sharing your knowledge with us.
Arrr, Sharing is my pleasure.... Martin
Another superb video Martin, & it's given me an Idea on how I might be able to cast this dammed WW2 diecast tail light I have been tinkering with for the last year!!!
War, Haven't you done that job yet - too much time spinning your wheels on country lanes methinks! 😊.... Martin
Fascinating, thanks for the series mate.
Lyall, My pleasure.... Martin
great video!
wwsoft, Thank you.... Martin
good afternoon Maartin. great information again, as always. i just landed a considerable casting job. all brass. would you use the same spru prinsipals for brass as aluminium.
Manus, Yes, definitely... Martin
saludos desde colombia
Heatsink fins would be easier with high pressure casting.
You can put degassing stuff in the metal before pouring too.
russell, Yes, it may well be easier to do fins with high pressure diecasting but you would need the quantity demand to be high in order to cover the cost of the much more expensive pressure die casting die.
I do degas any aluminium that I am going to cast into sand moulds but generally I do not degas metal destined to be cast in a gravity die. The much quicker solidification in a gravity die largely prevents gas being a problem. I degas with Argon gas and Iam not too sure what you mean by "degassing stuff" many people use the most useless of substances for this task, washing soda and epsom salts for example either of which will increase gas levels not reduce them.... Martin
Thank u so much for the amazing content. It is invaluable for us novice DIYers. I'm just curious how you get away with doing a direct pour on some of these die casts. I've tried it a few times in both ceramic shell and sand casting but with little success. All be it with rather questionable mix of alloys.
Your previous video entitled "possibilities" is a great source of information thank you again
Shannon, You are not wrong in seeing direct pour as a dubious process! I assume that by direct pour you mean top pour. It is bad because it risks turbulence that both generates oxide films and traps air in the casting. Thin is rather a pity for as I am sure you know it is often the easiest way to get metal into a mould. For the casting shown in this video I first tried it without the shell core "funnel" sitting on top of the ceramic foam filter. It was a complete disaster with 5mm diameter bubbles in every casting - due no doubt to the 100 to 125 mm fall of the metal as it filled the die. Use of the funnel and filter broke the fall up into two approximately 50 mm falls and no bubbles were ever found in now about 500 castings. Whilst having metal freefall at all is a bad thing it's all about the height of the fall. Thus I will always advise no fall at all but my experience is that 50 mm is ok but 100 mm is definitely bad and 200 mm catastrophic. So I use direct pour because it is easy and makes die design easy and cheap but I keep the fall height as low as possible - it is cheating I know but in the main it has worked for me. Note though that I use good metal - certified ingot from a reliable supplier. I would not like to try and achieve the same results with unknown junk scrap wrong alloy dirty oxide ridden etc. etc. metal... Martin
@@olfoundryman8418 thank you so so much for sharing your wealth of knowledge. I look forward to seeing your upcoming videos.
Thank you for sharing your experiences, it's truly very informative! I looked up the Dow Corning 3120 RTV Rubber and the useful temp range is only 300 degrees Celcius. I am looking to make molds in an easy way (not to have them machines in steel) to make zinc anodes which are pretty simple in shape, I am just not sure what to make the mold out of. If this rubber could handle the heat t hat would be great, I would 3d print the positive, then pour the rubber around it to have the mold and start pouring zinc. Would love to hear if you have any solutions. Thank you!
making, Yes, 3120 is not really rated high enough to take zinc but for thin work I got about 50 shots before the mould was useless. I also tried another brand of castable silicon (Wacker I think) it looked the same but broke down on the first shot! Zinc anodes tend to be thick so the castable silicon is a no go. I see two possible methods: 1, use a simple metal die - if the shape is simple with no re-entrant angles a die machined from aluminium should do either billet or cast aluminium. 2, Look up Tekcast - they are big in moldable silicon rubbers for spin casting - they even have a rubber that aluminium can be cast into (on a limited basis). Their web site is very informative. My choice would be #1... Good luck... Martin
Martin, @21:30 you say that quick cooling reduces porosity, but on many other occasions you add exothermic powder to keep metal hot in risers for longer?
That's so the feeder stays hot long enough to feed the casting adequately and avoid shrinkage issues in the casting proper (no problem if there is shrinkage in the feeder). Like many situations, it's a bit of a compromise.
I vaguely recall Martin saying that he takes more care to de-gas the metal when he is sand casting because of the slower cooling, but he can explain it better than I can.
Vlad, Adding exothermic to the top of the feeder is unlikely to have much if any of an effect on the solidification time of the casting proper so I doubt that it will increase gas in the casting. As dfross suggests the porosity in the feeder will likely increase but as we melt that down again it does not matter. You will note too that I sometimes chill the bottom of a casting as this will - apart from promoting directional solidification - cause the chilled area to solidify much faster hence less (if any) gas and a stronger more ductile finer structure.
Further to dfross's comment I rarely degas metal to be gravity die cast the quicker solidification means gas is unlikely to have time to precipitate out of solution even if the hydrogen level is above the amount that solid aluminium can theoretically hold. It simply stays trapped in super saturated solid solution in the aluminium where it does no harm and may in fact add to the metals strength through an alloying effect (solid solution strengthening) For slower to solidify sand cast work though I am a bit serious about trying to degas properly.... Martin
dfross, Thank you for your input please see my reply to Vlad.... Martin
Great vids, lots of good info and small nuanced teaching you only get from time invested.
Any chance you have a vid on gravity mould design?
I plan on my first attempt at home doing a metal form to make a product Injeed to complement my lil CNC shop, (trying to learn everything does not/should not be milked from solid! )
Brian, No, sorry I do not have a video on gravity die design. In truth I do not consider that I know enough about the subject to do a video on it (I know, I know this does not stop a lot of Utubers publishing but it does stop me!) Die design is an absolutely huge subject and one that unfortunately has more myth and legend than science involved in it. I am not bad on small simple work but anything big and/or complicated and I run away.
My "secret" to die design was to remember that a die is not empty - rather it contains air and if the air cannot get out the metal cannot get in. You see the results at things like internal corners where the metal will round out a little rather than fill the corner completely. A quick touch of die spray will fix the problem for a few shots (the air gets out under the metal through the roughness of the die spray) But a better way is to have some sort of joint in the structure of the die. The air will get out through the minute gap of the joint - if necessary shim the joint apart a "thou" or two. Hence as you say dies are best not milled from a complete solid - segmenting often makes machining easier too. I try to design a die so areas likely to trap air are on joint lines.
The other secret to making dies for one's own use is to make them oneself as to have others cut a die for you is way, way too expensive. Then you just have to hope that future sales of the parts cast will cover the cost of your time in cutting the die. This was the only way that I could get into gravity die work - I cut the dies and recouped the time later as best I could - it worked fairly well!
If you have a specific part come to me again and I will give you an address you can send details too and maybe - maybe - I can help with a design..... Martin
@@olfoundryman8418 ahh, the sign of a man how has been in the trade a long time, long past the "knows just enough to be a danger". respect! I do have 2 what I assume are simple parts in mind, a little advice would go a long way in saving me time/scraping parts!. I would be happy to share infornmation on them. better yet i can provide the CAD model if thats helpfull.
Brian, Come to me at olfoundryman@gmail.com with whatever drawings/models you have and I wil have a look. No guarantees mind you but I will sure have a good look.... Martin
@@olfoundryman8418 i have sent you an email. thank you again for your responces and videos :)
Of all the things that would be a stretch of my knowledge, every time I watch you, I feel that I should give gravity casting a try. What would be a good starter? Just trying lead, zinc, pewter?
Take a look into bullet casting just to give you an idea of simple permanent mold casting. Simple molds and melting pot. Lead alloys are normally used but some people have done zinc as well. Pick the metal that suits your application.
Normally bullet molds were made from cast iron but aluminum molds are also used.
Paul, As Rudy suggests you could look at bullet casting, generally I believe for older black powder relic weapons or perhaps a bit more universal the casting of fishing sinkers. All done in lead of course - although these days on environmental grounds lead free materials are being used. For home casting these would likely be tin bismuth alloys -absolutely great to cast as bismuth does not contract on solidification, it actual expands so a 50:50 tin bismuth alloy neither contracts nor expands makes casting a solid product easy but the metals are expensive. You can buy fishing sinker moulds quite readily so it would be an easy starting place and you can melt the lead or tin/bismuth in a tin can (NOT a soldered one)on a gas stove or barbeque. Most of these moulds are designed without (adequate) feeders for the casting so getting a good solid useable casting can be a question of mould and metal temperature plus pouring technique. It often helps to smoke the mould with a sooty flame. Some people do all sorts of very interesting work in the metals you mention into static silicon rubber moulds... Martin
Rudy, Thanks for your input... Martin
hi martin, thanks for capturing all this on your vids, it is most informative and inspiring. Can you pls list all the sprays and powders you apply on the aluminium molds before and after pouring? Also, is there a reason you did not cast the molds in steel or iron vs aluminium? wojldnt a steel molds be more "durable"? Pls advise, thanks !
wouldn't*
Quentin, I spray the hot die with a mold coat called 14ESS, it is made by Foseco. This is an insulating coat that allows the metal to run and fill the die. Also it helps with air removal from the die. It is my most used die coat. On some parts of the die I use a topcoat (i.e. over the 14ESS) of "Release Coat Blue" by ZYP coatings. This is a coat based on boron nitride and is a very good lubricant thus it aids release from the die - it is however rather expensive. I use a paint on dry MoS lubricant on parts of the die that slide against each other. I also use some graphite powder on some parts of the dies and the machine that holds them, again it's for lubrication purposes. Most of my dies are in fact cut from cast iron. It is a better material than mild steel - higher conductivity for a start and it tends to hold the spray better. It is easier (if a bit dirty) to machine than steel would be. Only a few of my dies were ever made from cast aluminium, these are short life dies and even then can only be used where the part being cast does not contract onto the die - an aluminium die might last 500 shots a cast iron one many tens of thousands of shots. Does this answer your question? ... Martin
@@olfoundryman8418 it exhaustively answers the question, thank you very much for the details. As mentioned, your videos are very informative. Please keep going, "drop" all you've got on youtube !
8:37 is that shrinkage or is finding cavities in the mold to fill
Bobby, Shrinkage - remember aluminium alloys shrink by about 7% on a volume basis...... Martin
Hello foundryman, could you please show us your own process of the lost PLA Casting if possible? it's what i do mostly at the foundry, i 3d print a Figure (Mostly small Japanese Cartoon Characters) and do a simple PLA Casting but i get lots of Problems and issues, i just keep trying till i get it randomly right, without knowing what's the issue
David, I have never done lost PLA casting! However I have watched many on UT attempt it with varying degrees of (non) success. The mistakes that many make are (to me) obvious. If you can come to me at olfoundryman@gmail.com with photos of results and a description of what you do and what you use to do it I may be able to help. Considering what you are trying to produce 3D printing is not an unreasonable starting point.... Martin
I'm about 12:30 into the video, and a question occurred to me. Are gravity dies ever filled through a filter or does it tend to be directly poured in from either a ladle or the reservoir shown in your tilt setup?
elitearbor, The 4 barrel throttle body shown being cast near the end of this video is poured through a filter. If I was doing larger and thus likely higher work I would make greater use of filters as they are invaluable in slowing metal velocity down, but most of my casting work is low head height and therefore has low metal velocity - filters are not so necessary under these circumstances. I think it might be somewhat difficult to use filters in tilt work, not impossible mind you, just a bit harder to implement... Martin
Thank you for the thorough explanation! It's good to know that filters remain an option even with this kind of casting. I'll have to rewatch the throttle body casting, I forgot about there being a filter involved.
Thank you for another great video! What are your thoughts on stacking or layering of the metal used to construct your die? I'm trying to produce a part that's around 4" tall and I am having trouble finding material large enough to be able to machine a solid die. I think you might be doing something similar on your four barrel die? It looks as if there might be a 0.5" plate bolted to the top side of the die making up the feeder height? or is that just wishful thinking on my part? :)
Jerred, I like to stack material as the mating faces of the "stack" are never an exact molecular fit so even if well machined they provide minute gaps through which air can escape. Gaps that I might add can be increased with some very thin shim if needs be. There is indeed a plate bolted and doweled onto the top of the two side pieces of the die. This had two important advantages - it made it possible to cut the die in two parts i.e. above and then below this joint line as separate and much easier operations than trying to do it in the one solid. Also and even more importantly it allows air to escape and thus the edge of the casting's mounting flange forms well - if the die had been cut in the solid this edge would likely have rounded because of trapped air. I could easily have got material thick enough to make the die in the solid but I deliberately designed the die with this layered structure. I considered that stacking - IF JOINTS ARE CHOSEN WITH CARE AND PURPOSE - is very much a positive but do remember that it is usually necessary to pull the "stack" apart and clean between layers when readying the die for its next run..... Martin
@@olfoundryman8418 Thank you Martin, I hadn't considered using a 'stack up' for releasing trapped air but that totally makes sense. I started watching your videos forever ago and seeing you produce quality castings they inspired me to try and produce some parts I'd like to make. I realized sand casting was not going to be practical for my needs somewhere around your reflector blanks and throttle body videos where you discussed using a aluminum die, I think.. Already having a cnc, I'm attempting to design a die, which is quite a process.. My hat goes to anyone who has done so. Anyway, I'm in the early stages of machining the mold components but if I run into filling issues it's great to know a potential fix.. Thank you once again.
I remember from your four barrel throttle body video you said that you were using a filter not to filter the metal but instead to reduce turbulence. (as close as I can remember) I don't recall seeing you use filters in any of your other videos. Do you think there is any benefit to using a filter in sand castings, or is it not worth the trouble. (easier to use with permanent molds than fragile sand molds)
Check out Martin's series on casting a piston for a 1910 Brush. He uses a ceramic filter in that casting (which was done in sand).
Link to part 1: th-cam.com/video/kf2xae2J9HE/w-d-xo.html
Rudy, dfrossis right I do use a filter in the sand casting of a piston. This is a high mould (for me) and with greater mould height comes greater metal velocity and thus the possibility of greater turbulence. Filters are great for slowing metal down, you can get a speed reduction in the metal stream of 3 to 5 times by incorporating a filter into the running system. For this piston we used a filter at the base of the sprue such that the metal had to go through the filter and then into the runner bar - the runner bar was 4 times the cross sectional area of the sprue exit. The filter reduced the metal velocity to a much safer level. I rarely use filters in my sand work because my moulds are quite low and metal velocities are therefore also fairly low. However if I were to use higher moulds I would likely use filters. In the case of the 4 barrel throttle body I top pour the casting and this is to be honest a recipe for disaster as it is a very turbulent way to pour. Initially I did not use a filter and every casting was found to have 3 to 5 mm air bubbles trapped within it and revealed on machining - clearly the result of turbulence from the metal falling straight to the bottom of the casting - a fall distance of a little over 100 mm (4 inches). By using the filter I cut the fall down to two falls of 50 mm (2 inch) each - way less turbulence and in now about 1000 castings no air bubbles.. Filters are fairly cheap at about $0.50 each. While perhaps a bit more difficult to use in sand moulds there are ways of successfully incorporating filters in them. Martin
dfross, Thank you for pointing that out.... Martin
What exactly is the steel alloy that the die is milled out of?
Phylis, The large round base plate is mild steel, all other parts of this die are grey cast iron machined from continuously cast bar....Martin
@@olfoundryman8418 you mean I can machine my own aluminum dies from cast iron!
Amazing. Just saved me lots of money. Im trying to cast some pulleys (10 inch/25 cm diameter) out of aluminum and I'm honestly very new to casting anything. This would be of great help. Thanks so much, Martin
Phylis, Yes, you can use grey cast iron to make dies from. In fact it is a rather superior material as it has higher thermal conductivity than most steels and it tends to have a little "roughness" due to the presence of graphite in its microstructure. The graphite being very soft eats out a little and the resulting slightly uneven/rough surface provides excellent keying for the die coats that need to be sprayed on the hot die. Good luck .... Martin
Maybe it is stuppid question, but it is possible to cast aluminium die, and then use it to cast aluminium without damaging die?
Mat, It is certainly not a stupid question, I have cast thousands of simple aluminium parts into aluminium dies. BUT there are limits - the process does not work with parts that will contract onto the die as this will cause rapid die wear. Die life is short, even with simple parts 200 to 500 castings is about it. But you can make the dies easily quickly and cheaply so it can work well. I have a 4 part video series that shows the whole process from making the masters to cast the die around through making (casting) the die to casting the parts. Here is the link to part 1 of this series th-cam.com/video/hVdLDFAgJBg/w-d-xo.html I cast the die in a piston alloy... Martin
@@olfoundryman8418 so two choices? make die from alu/sil/bronze/ or boron nitride coat on alu die?
Mat. The boron nitride spray helps because it is a good high temp lubricant but it still will not allow a "contracting on to the die part" to be produced. Whether or not an aluminium die can be used depends very much on part design.... Martin
Another great video. What do you think of Tesla casting the whole front & rear of a car?
Andrew, Tesla, yes, a most bold adventure using I think the biggest high pressure diecasting machines ever built - hate to think what the die cost...Martin
Olfoundryma~n Hey! excellent .🤩
Pro, Thanks for saying so... Martin
I see a lot of similar heat sinks in the electronics world, but pretty much they're always some kind of extrusion.
Scodiddly, Yes, you are right. The vast majority of heat sinks are extruded and considering the difficulties of casting them I am not surprised. Once you have the extrusion die you can put out miles of the stuff and just cut to length - so much easier and cheaper.... Martin
Been watching your videos... A few things maybe you could go back to the basic for the benefit of the viewer the white powder (ash bones?) You are using and the pro and cons if not as well as the powder you use on the risers and the benefit of it. Thanks. ed
Edouard, Is the white powder that you're referring to the parting agent that I use with my sand moulds? If so it is finely ground Calcium Carbonate. This material is used commercially as a parting agent for green sand moulds and is considered much healthier than using Talcum powder which (possibly) has an asbestos risk. The dark red powder that I use on the feeders is an exothermic called Ferrux NF it is made by Foseco. Its job is to catch fire and generate a lot of heat that keeps the feeders liquid for longer so they are better able to provide feed for the solidifying casting underneath... Martin
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Skip, Thanks.... Martin
And not a video of machining a mixer anywhere to be found. Who had time for TH-cam at that time!
small, Yes, it's a pity that we do not have a video of machining one of the many mixers we collectively made - it would have been a nice addition .... Martin
Compared to the videos made 1-2 years ago you sound way more lively which, hopefully, means your health snags are gone!
noob, Sadly, no! This whole gravity die video series was filmed way back in August 2019. My health snags still plague me and this is why any recent video releases (with the exception of the "stirring" video) are of material shot some time ago. I am trying to shoot some new stuff, primarily to finish the metal moulding box saga, but it's a question of how much I can get filmed before the pain forces me to sit down and stop - Old age is a crock of crap!....Martin
@@olfoundryman8418 Ugh, sorry to hear that! Sounds like you're between a rock and a hard place, on the one hand looking to 'do something' to keep your mind busy, on the other that something is painful. Maybe do a more theoretical series about alloys and in what cases to use them ? Heat treatment also might be a short topic.I'm sure there's plenty of knowledge that you're glossing over as it's a second nature for you but people have no idea about.
noob, Ugh indeed! "More theoretical" is a road that I do intend to go down, I have several videos in mind including one on heat treatment. However there is a bit of a hump (or two) to get over. I need to create with my hands - I can create with my mind but it just is not as satisfactory, so far I have no way around this disincentive. Often too mind creating requires some hand creation. Then there is the problem with pain and indeed ill health generally in that it grinds you down and seems to rob one of incentive, enthusiasm, and energy - lethargy takes over and little gets done so it's a slow business. Still, one foot in front of the other I guess..... Martin
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Aquila, Thanks.... Martin
Interesting work. Enjoyed the comentary. Thanks for the look.
John, Thank you for looking... Martin