Always a pleasure Poppa P . That bag and blow demonstration was brilliant 👌🏻makes so much sense and explains why your always got the perfect castings happening & why mine take 15 goes to get it half right🤦🏻♂️. Cheers for the email buddy👊🏻😁
Thanks Dave, then you've seen some changes havent you? 😃 I'm working on a... well the parts are in my garage... a new furnace. I hope to do a build video on it.
I'm glad I watched this to the end. I'm just learning to cast metal and I already understood the fluid dynamics but to see it applied in this way was literally mind-blowing because its not shown by other melting and casting TH-camrs and I would have never thought of this. Brilliant...just brilliant. Funny thing...I was wondering why your castings look better than a lot of other videos. Now I'm beginning to see there's a lot more to it than just buying the sand and making molds. Keep the videos coming!
I'm glad you watched to the end too 😄 There are a few other channels out there that are interested in teaching proper this same methodology, olfoundryman is one. Another new video from me tin a few hours on the next pieces of the system. Hope you watch it as well
There's actually a couple of jet and rocket engines that use the same principle to nearly double their thrust. Check out ejector rockets and ejector ramjets. High velocity stream of fluid entrains atmospheric air and fwoosh. Trade a little exhaust velocity for a lot of mass flow rate.
Just found your series - Wish I had some time ago ;( One thing I wish you had described in more detail was the "Spin Gate" - dimensions and shape. Many thanks for this informative set of videos.
The dimensions are kinda made up. I just did what looked right and proportioned. The idea is to redirect the surge from the initial filing of the runner from splashing back on itself. As long as you are putting something round out on the end I think you're fine. The round part needs to e tangential to the side of the runner so the metal is gently redirected into the circle. I've see some guys do it where the make it look like an "i" with the circle centered on the end of the runner. That won't work and will likely cause more turbulence.
I've gotten fantastic results using a scratch awl as my tapered sprue former. It's unbelievable how tiny of a channel aluminum can flow through and still fill the mold
I’ve been catching myself up on your tutorials, and I honestly believe that if public schools had more teachers like you, kids would be a lot more interested! I can’t wait to start applying everything down the road...
Chris, I cannot tell you what your comment meant to me when I read it last night. I was editing this week's video and feeling "what's the point?" and having trouble finding the motivation to get through it. Thank you so much for your kind words, they have lifted me up!
swdweeb speaking from experience, my favorite subjects were always the sciences. The one teacher that stands out to me, still to this day, had your attitude: you could tell that he loved what he was doing, he honestly enjoyed it, and he wanted to share his knowledge with others. So long story short: you’re great, and please keep it up 😁
Perfectly explained . I am following your videos since you uploaded Bob's videos . The video helping me alot in designing my gating system in permanent mould castings . Looking forward for more videos.
@@sourabhkulkarni2515 You might want to check these out th-cam.com/play/PLU1QP34Dv8Y6lbvgqXuvCPEnXeE4IgWgr.html They are from a real expert. I have no experience with nitrogen degassing or any other type of degassing for that matter. Sorry. In my opinion, we can do far more to reduce the porosity of our castings by controlling the pour and flow through the mold than microscopic degassing will do. Just my opinion, don't hate me for it.
Thank you for doing these videos with demonstrations that are simple and easy to follow (especially for us mathematically challenged individuals). Keep up the great work and stay safe.
Great demo. I agree that the offset pouring basin is inextricably tied up in all this - even a tapered sprue will suck air if you use a funnel shaped pouring basin. It's the venturi effect. Your propane burner is probably designed to suck in all the air it needs in the exact same way, just like the amazing plastic bag demo. Looking forward to the next episode!
Yeah, man I really debated...still am... whether to do the basin next or the runner/gate(s). all three are tied together. Maybe I should do the .... aaauugh it hurts my head to think about it. ;-)
@@swdweeb I don't think that he is referring to the sprue, but rather that overheating the metal can increase the risk of developing porosity in the casting.
That same principle applies in burners , it’s called ( venture affect ) . That’s how we get the blue flame . The gas jet pulls in outside air as in your demo making the flame change from rich yellow to an oxygenated blue .
Thank you for sending me here from your aluminum bronze hammer video. I didn't realize how old that other video was before I commented which is a little embarrassing, I should have checked before. I definitely don't think that hole was shrinkage though. The top of your casts with the divot definitely is, but that hole on the face isn't uniform at all. It looks like sand collapsed a little while you closed it which you thought may have happened and that's what caused the hole on the hammer face. I could be wrong though, at the end of the day, you fixed it and it looks great. You're awesome.
Yeah, that's a problem with TH-cam. Things like follow-up videos really don't get posted in a way that people notice. It happens all the time. I can tell you that two people that are professional foundry people have each told me that the hole is a void caused by molten metal inside the part shrinking away from the chilled metal of the surface. Here's another video for you to take a look at th-cam.com/video/IYqpHAxBLOI/w-d-xo.html
Awesome video Perry. Lovely explanations. I really loved your awesome science stuff, really good. any John Campbell book is the bible. I've read the fat one at least twice now, the trouble is... i forget stuff which is why i love this series! Also when i cast my cannon the tapered sprue will be about 35+ cm (i too am not a mathematitican - i reckon the metal will be going light speed by the time it gets to the bottom!)
@@raschellesherwood6347 Yeah, that's how I found out about you, watching you riding and videoing her in front of you. A million years ago I used to be motorcycle race enthusiast. Rode (had a Kawasaki Z1-R) to Laguna Seca and watched Kenny Roberts a couple of times. When that guy was on top, he was on top. No one could touch him.
I've offered a measured drawing and an stl file for over a year now free for download. All you had to do was ask. Sorry you didn't know. I would have gladly given you the measurements earlier.
@@swdweeb My apologies please, my comment came across SNOTTY, unintentionally. No longer have access to a 3D printer so making the tapered sprue on a wood lathe. Never thought to ask for measurments, shades of Wayne & Garth meeting Aerosmith. Keep up the good content.
@@honthirty_ Ha! You'd think at my advanced age I'd think Wayne and Garth are stupid.. I can watch them over and over though 😃 No worries, I was really more concerned that I hadn't done a better job letting people know. I have a new square sprue debuting next week... assuming it works... that I'll make sure I post the dimensions for.
My first video of yours and I’m hooked for life 👍👍😊👍👍. Good thing I could subscribe so I don’t miss any future installments 😜. And that bell..... man this is great. Thanks for the very enjoyable lesson.
Speaking of porosity, we got some replacement sub-floor vents cast in aluminium for one of the period buildings at the school I work at. The face of the casting was ok but the sides were filled with pin holes and this was from a professional foundry. Go figure!
Old Iron Shops : Dang you still alive? Thought either the flue or the wild fires got you. I know this is your busy season but How about posting every now and then so we know you're all right
I wanted to do a cast with a tapered sprue since I started sand casting, but I still have no proper sprue pattern. (got a tapered pattern from an empty sew yarn roll, but that is a little short) With this information in mind, I really need to be on the look out for a proper sprue! Will defenitely improve my casts! I guess you need various diameters of sprues for different sized casts? For example, if I want to cast an aluminium cast of 3 kg, that small sprue will result in lack of liquid metal in my mold and causing freeze ups before it completely fills the mold right? I think when you go big, you need a bigger sprue and pouring cup, or am I completely wrong on this?
Very informative, thank you and cheers from Italy! ( I have a request, how strong/stiff is cast alluminium compared to other metals? It would be a great video 😊)
That would be a good video. I know the different aluminum alloys exhibit different strengths. I've read that some are as string as steel. I'm not set up to do any of that kind of testing or reporting but it would be interesting. Ciao amici
I don't know that sprue size and metal type are directly related. If a metal needs to fill a mold quickly a larger sprue might be required. I'll have to ask. I just don't know. I've use the same sprue for aluminum, brass and different bronzes
Acceleration due to gravity does not depend on material density. This is why a bowling ball and a feather will fall together in a vacuum. This has been done and is probably out on the TH-cams.
Troye Welch : It is understood that gravity is a constant, however this is a specific gravity question. If you are using different metals then the diameter of the sprue should change in order to maintain the desire flow rate,
Bernoulli or www.latimes.com/includes/projects/hollywood/portraits/valerie_bertinelli.jpg never quite sure 😃 I think this is bernoulli marineengineeringonline.com/operation-maintenance-eductor-ships/#:~:text=Eductor%20is%20a%20simple%20type,the%20ship%20including%20hazardous%20areas. but I'm just a meager software guy. 😃
I am curious about the relationship between the size of a part to be cast and the most appropriate sprue size. I recently cast a 9 pound part and after a few failures it seemed like a larger sprue helped completely fill the mold before the metal froze.
There are calculations... here's where you know I'll fall apart... that give you stuff like freeze rate and from there I expect you can figure out required volumetric flow rate. I know that larger castings require larger sprues for larger volumetric flow. I'll ask my foundry friend Nate if he's got anything to offer.
@@jamesmartell8787 Adam is a good friend and he does what works well for him. I cant argue with his success and I'm really happy for him. He's a good guy
You made an aspirator or an eductor with your bag demo. The same principle is used to fill escape slides on passenger aircraft. The slides on an Airbus A380 have to inflate in under 2 seconds. They use a chemical rocket which fires through an open venturi to drag sufficient air to fill the slide and cool the rocket exhaust. A great demo and explanation but you almost lost me when you mentioned "mathematics". 😬
An eductor?? Come on Mark you hurt my little brain when you use big words like that 😃 I had to go look it up to see what it was, but yes apparently I did. 😃 Yeah, I'm pretty decent at arithmetic but that math stuff throws me every time. Had to call my son on how to move a variable from one side of the equation to the other. He said "come on dad you just divide both sides by the stuff you want to move" Sigh...
You want to divide your flowrate ( length cubed per time) by the velocity (length) and that will give you the cross sectionla area (length squared) of the pipe ( not the diameter). You points are still good though, nice video!
You guys are trying to sound fancy by using the word velocity instead of speed. The only difference is that velocity is speed with a direction. This only becomes important when you’re adding multiple vectored quantities together so you can add the separate components (x, y, and z, for example). Since we are talking about a vertical sprue with only a 1 dimensional component (z), the direction is implied and it’s not really a vector quantity in this context. Here, the word “speed” is fine... using “velocity” when “speed” would do only makes you sound smarter to people who don’t know any better (see the movie “Idiocracy”) NOW. If you put the sprue in at an angle, you would have both a Z and an X/Y component. Gravity would only accelerate in the vertical direction, so the final speed (or velocity if you still want to go there) would be less for a given sprue length than a vertical one. This should make sense if you think about it. Further digging will reveal that it’s proportional to the cosine of the angle deviation from vertical (100% at 0 degrees deviation and 0% at 90 degrees)
Yeah I was just trying to say that what we're calling the size of the pipe is actually its cross sectional area and not the diameter...so the spreadsheet needs a sqrt() in it somewhere
@@swdweeb no problem! Your videos are amazing, you have alot of knowledge about something I've always wanted to do but never had the money for the basic supplies. Your videos are inspirational! I can't believe you don't have over 100,000 subscribers
Would not a large feeder also allow inside air to be displaced, provide constant fluid feed and head pressure due to its weight? Can a small tapered sprue feed?
Can a small tapered sprue feed??? Of course it can feed. Head pressure isn't all it's cracked up to be. th-cam.com/video/_3lwlBx6-YA/w-d-xo.html Abd you certainly don't need a large feeder to displace air th-cam.com/video/fvSHwvTyApk/w-d-xo.html
Would this apply to vacuum assisted lost wax casting? I’m using a pretty large straight sprue. About 20mm in diameter. Each pour is about 9kg of brass.
Man, I'll be completely honest, I have never done any lost wax stuff. I marvel at the sculptures that come out of it all of the time. That said, know that everything I'm about to say is opinion based on zero experience doing what you do. I think in general bottom filling and reducing the entrainment of air in the pour is a good thing. To that end, a tapered sprue that is kept full during the pour has to help with the amount of air that enters the mold. To what extent the vacuum helps with entrained air, I don;t know. Sorry I wasn't more help.
swdweeb, this video was very helpful. Thought provoking. We actually fill from the top. During burnout the gate has to be at the lowest point of the casting so that the wax is able to completely empty the cavity. We already get very nice castings, but I think that a smaller and tapered sprue could be beneficial. We often have up to 10 parts in one flask arranged around the sprue at varying distance from the mouth of the sprue. The vacuum certainly helps fill the cavities fully. The parts are either very ornate door handles or wiring channels that cannot be machined because features of the parts block access for a drill. The waxes are assembled from two parts so that the holes align. Thanks again for the videos.
@@swdweeb hahaha no i dont. But yeah. Our garage was actually sorted well kinda. Everything packed away by the helper now you need a search party if you want something.
@@frikkiesmit2695 I could have someone come in and organize, that would be great. Then I need someone to beat me over the head telling me to put stuff away after I'm done. 😃
Darn good question. It all comes down to how fast you need to fill the part. When you pour in a tapered sprue, its important to keep the sprue full the whole time. That means pouring as fast as it will take the metal. The smaller the sprue, the less metal you'll get to the runner. What is one ounce of silver, like a quarter (currency)?
@@swdweeb bigger than a quarter. An American Silver Eagle is a 1 troy ounce coin. It has a diameter of 40.6mm. It is 2.98 mm thick. So 1.598 inches across and .1173 inches thick.
@@billsaunders1879 Keep in mind, I've never poured silver. That said, I would think a part that small could use a smaller sprue than what I use but I'd probably still just pour it with what I have.
@@swdweeb thank you. I make coin rings. From 90% silver coins and also 999 fine silver bullion. I have to punch out the center before I make the ring. I have been saving my 999 fine silver punch outs to make castings with. I have been selling the 90% to local silver dealer. Apparently the 90% stuff is not was appealing to collectors and is harder to sell items cast from it. Lol I wish I had more 999 fine silver but I only have 6 oz right now. If the smaller spue and spin gate don't work then I will have to wait until I have more punch outs or possibly buy some bars with the money from the other scrap. I will let you know how it goes.
It seems logical that a tapered sprue would lead to less turbulence of the poured melt, and therefore less entrapped air. However the viscosity of the molten metal would not be the same as the viscosity of water, which would make your calculations dubious. Think of sucking honey compared to water through a straw. I suspect that your very nice casting has as much to do with the offset pouring basin, the spinner, the quality of the aluminium, the side-bottom feed and the quality of the mould. I imagine that molten aluminium has a higher viscosity than water, which would make the velocity of the melt even lower, and better, than your calculated value. But great food for thought. And thank you. I will try a tapered sprue!
The experts, Professor Campbell and Bob Puhakka all seem to treat the speed of the metal as if it is falling water. I've yet to read or hear them talk about the viscosity being an issue. I will ask Bob in my next conversation with him to see what he says. I personally do not know the difference in viscosity between melted aluminum and water. You are correct taht the quality of the casting has to do with all of those things. In the interest of keeping the videos brief, I cannot talk about all of the components together but none of them work without the other. It is a system.
If you watch a lot of aluminium pours the molten metal does behave almost the same as water only just a little bit slower. Some foundries pouring large quantities of aluminium direct the pour from the crucible to the molds via ceramic troughs almost like aquaducts. They have to preheat them first with a propane burner, but when the aluminium is released it is very much like watching water flow.
Mark Fryer “a little bit slower” is my point. I would like to know the number to see if the mathematics or arithmetic stacks up. The viscosity of molten aluminium and bronze would be relevant. I do not possess s copy of Prof Campbell’s book and cannot find the number elsewhere. Johnsmachines.com
Thank you for doing these Perry. Much appreciated. Like others here I imagine, I have been casting for a while, but I need to review the basics to try and correct my ongoing rookie mistakes. Shameless plug, I made a video a few weeks back inspired by the videos you hosted for your friend Bob Puhakka and also Andrew Martin's experiments. th-cam.com/video/GwqENPFqPBM/w-d-xo.html. Also, would you consider doing a basics lesson on sand management? I pull my hair out trying to guess at the right moisture content to maintain. Thanks again.
Shamelessly plug yourself all you want. I watched both videos. Good stuff. Regarding sand, that's a tough one. I thought I put a really quick spot in one of the "learning" videos but I couldn't find it so I guess it ended up on the cutting room floor as it were. It really is a trial and error thing for me. I have settled on a ratio of about 2 liters of sand and 36ish ml of water for my ratio. I have a cup that holds about 400ml of sand and a little cap that holds about 6ml of water. I mix five cups of sand with 6 caps of water. I let my sand dry out between uses. That does two things. It gives me a consistent starting point for how much water and it keeps it from developing a moldy smell to it. I'm the only one that I know of that seems to get that smell, but I don't like it so I let it dry out. The downside to this is I have to prepare my sand before I cast anything. When you just want to run out there and cast and think "Doh... I've got to make sand first" it can be a bit of a discouragement. Bottom line on the sand is I've found a moisture content that seems to work well for me and now I know what it feels like. So I can stick my hand in it and tell if its too wet or dry. I've kinda forced myself to do it that way as I want to be able to simply grab some sand know that its where I want it to be
@@swdweeb Thanks for the reply. I like your consistent approach, but having to re-wet sand every time goes against my lazy nature. I think I might try drying out a portion as a test and then adding in water with the ratio you mentioned.
@@charliekrauter5176 trust me, I wish I could just store sand that was ready to go and use it whenever I want too :-D I tried that and as I said it smelled of mold when I opened the container. Probably because it was moist and sealed and in a garage that gets to around 100F in the afternoons. I know other people are able to store their sand in sealed containers so they only have to go through the re-wetting occasionally and do it in large batches. Just didnt work for me. Good luck with it. You will likely find "your mileage will vary" on the amount of water but play with it and get it to where you like it.
Always a pleasure Poppa P . That bag and blow demonstration was brilliant 👌🏻makes so much sense and explains why your always got the perfect castings happening & why mine take 15 goes to get it half right🤦🏻♂️.
Cheers for the email buddy👊🏻😁
Its the magic of selective editing. My castings don;t always go anywhere near perfect mate 😁
The bag demonstration is actually an old bar trick. See who can blow it up the fastest. You’ll win with that method everytime 😉 great vid 👍🏻
Ha! Who would have guessed. I'll have to let professor Campbell know that. He'll get a laugh out of it.
I've been with you since the beginning, love these lessons. Build some furnace concepts too, you know that,ll catch eyeballs.
Thanks Dave, then you've seen some changes havent you? 😃 I'm working on a... well the parts are in my garage... a new furnace. I hope to do a build video on it.
I'm glad I watched this to the end. I'm just learning to cast metal and I already understood the fluid dynamics but to see it applied in this way was literally mind-blowing because its not shown by other melting and casting TH-camrs and I would have never thought of this.
Brilliant...just brilliant.
Funny thing...I was wondering why your castings look better than a lot of other videos. Now I'm beginning to see there's a lot more to it than just buying the sand and making molds.
Keep the videos coming!
I'm glad you watched to the end too 😄
There are a few other channels out there that are interested in teaching proper this same methodology, olfoundryman is one.
Another new video from me tin a few hours on the next pieces of the system. Hope you watch it as well
Thank you for educating me 🙂
My pleasure! 😃
Your "Learning to Cast Metal Series" is Awesome. Thank You, Perry
Thanks boss. I appreciate that.
I was impressed with the air bag demonstration, who’d have thought, excellent.
Great series, cheers. Peter
Thanks Peter, yeah that is one great demo. Wish I'd thought of it :-D
There's actually a couple of jet and rocket engines that use the same principle to nearly double their thrust. Check out ejector rockets and ejector ramjets. High velocity stream of fluid entrains atmospheric air and fwoosh. Trade a little exhaust velocity for a lot of mass flow rate.
Learn something new everyday, Thankx to you and these videos. Please keep them coming sir. “Splat calculator”amazing tool
splat calculator, great name too 😃 Thanks, I'm intending to keep them coming. I''ve got a lits of topics on my whiteboard yet to cover.
Love the content. Love your passion. Thanks, Perry. Great vid as always.
Thanks Darin. I'm enjoying this series
Just found your series - Wish I had some time ago ;( One thing I wish you had described in more detail was the "Spin Gate" - dimensions and shape. Many thanks for this informative set of videos.
The dimensions are kinda made up. I just did what looked right and proportioned. The idea is to redirect the surge from the initial filing of the runner from splashing back on itself. As long as you are putting something round out on the end I think you're fine. The round part needs to e tangential to the side of the runner so the metal is gently redirected into the circle. I've see some guys do it where the make it look like an "i" with the circle centered on the end of the runner. That won't work and will likely cause more turbulence.
I've gotten fantastic results using a scratch awl as my tapered sprue former. It's unbelievable how tiny of a channel aluminum can flow through and still fill the mold
Sorry for the delayed response. I agree, I'm always amazed at how far molten metal will flow through narrow spaces
I’ve been catching myself up on your tutorials, and I honestly believe that if public schools had more teachers like you, kids would be a lot more interested! I can’t wait to start applying everything down the road...
Chris, I cannot tell you what your comment meant to me when I read it last night. I was editing this week's video and feeling "what's the point?" and having trouble finding the motivation to get through it. Thank you so much for your kind words, they have lifted me up!
swdweeb speaking from experience, my favorite subjects were always the sciences. The one teacher that stands out to me, still to this day, had your attitude: you could tell that he loved what he was doing, he honestly enjoyed it, and he wanted to share his knowledge with others. So long story short: you’re great, and please keep it up 😁
Perfectly explained . I am following your videos since you uploaded Bob's videos . The video helping me alot in designing my gating system in permanent mould castings . Looking forward for more videos.
I think gating is the next video. I keep going back and forth between gating an basin, which to do next.
Video on gating calculation will be nice . If possible make a video on nitrogen degassing effects on porosity . 👍👍👍👍
@@sourabhkulkarni2515 You might want to check these out th-cam.com/play/PLU1QP34Dv8Y6lbvgqXuvCPEnXeE4IgWgr.html They are from a real expert.
I have no experience with nitrogen degassing or any other type of degassing for that matter. Sorry. In my opinion, we can do far more to reduce the porosity of our castings by controlling the pour and flow through the mold than microscopic degassing will do. Just my opinion, don't hate me for it.
Thank you for doing these videos with demonstrations that are simple and easy to follow (especially for us mathematically challenged individuals). Keep up the great work and stay safe.
Hey, we have to stick together 😃 Thanks
Looks like you have learned a lot from Oldfuoundryman Perry. Keep up the good work. Love your presentation and simplification.
Thank you, and yes I did
Great demo. I agree that the offset pouring basin is inextricably tied up in all this - even a tapered sprue will suck air if you use a funnel shaped pouring basin. It's the venturi effect. Your propane burner is probably designed to suck in all the air it needs in the exact same way, just like the amazing plastic bag demo. Looking forward to the next episode!
Yeah, man I really debated...still am... whether to do the basin next or the runner/gate(s). all three are tied together. Maybe I should do the .... aaauugh it hurts my head to think about it. ;-)
Using a tapered sprue is a good way to reduce porosity, as well as not overheating the metal.
Not overheating the metal??? You've got me intrigued. How does it help that?
@@swdweeb I don't think that he is referring to the sprue, but rather that overheating the metal can increase the risk of developing porosity in the casting.
minute 6:15, hahahahaha a guy s free fall picture
One of my better videos, in my humble opinion.
Well done Perry! As always you love of Metalcasting and teaching does not go unnoticed! Keep me coming! 🤙🏼👊🏼
You're a prince bud. Thanks for all of your help. I'll be bugging you about next week's video shortly 😃😃
Great demonstration.
Thanks
Excellent demo! You have a great day! and thank you.
Thank you!
That same principle applies in burners , it’s called ( venture affect ) . That’s how we get the blue flame . The gas jet pulls in outside air as in your demo making the flame change from rich yellow to an oxygenated blue .
Minor spell check. Venturi effect.
Very educational sir!
Oh and FIRST!
Well, first is what counts 😃😃 Marc. Thanks bud
thanks
Thank you for sending me here from your aluminum bronze hammer video. I didn't realize how old that other video was before I commented which is a little embarrassing, I should have checked before. I definitely don't think that hole was shrinkage though. The top of your casts with the divot definitely is, but that hole on the face isn't uniform at all. It looks like sand collapsed a little while you closed it which you thought may have happened and that's what caused the hole on the hammer face. I could be wrong though, at the end of the day, you fixed it and it looks great. You're awesome.
Yeah, that's a problem with TH-cam. Things like follow-up videos really don't get posted in a way that people notice. It happens all the time.
I can tell you that two people that are professional foundry people have each told me that the hole is a void caused by molten metal inside the part shrinking away from the chilled metal of the surface. Here's another video for you to take a look at th-cam.com/video/IYqpHAxBLOI/w-d-xo.html
Awesome video Perry. Lovely explanations. I really loved your awesome science stuff, really good. any John Campbell book is the bible. I've read the fat one at least twice now, the trouble is... i forget stuff which is why i love this series! Also when i cast my cannon the tapered sprue will be about 35+ cm (i too am not a mathematitican - i reckon the metal will be going light speed by the time it gets to the bottom!)
Only 2.62 m/s mate 😃 The little book is great for a quick reference. Professor Campbell did a great job boiling it down and keeping it really simple.
swdweeb ooooh thanks ill have to get a copy!
Great demonstrations, you have a skill for teaching, thanks for sharing the things you have learned!
Thank you, I really appreciate that
great work as always perry. simple effictive and above all factual information. great job and great examples. keep up the awesome work mate!!!
Thanks Raschelle. I appreciate that. Just out of curiosity, "R" or "J"?
@@swdweeb j lol how did you know about both of us? I didnt even realise to be honest. I dont have a youtube account
@@raschellesherwood6347 Because most women, my wife and daughter included, don't give a rip about what I post on YT :-D
@@swdweeb that's halarious hahahahaha good call . But shell races motorbikes so shes not the typical female lol
@@raschellesherwood6347 Yeah, that's how I found out about you, watching you riding and videoing her in front of you. A million years ago I used to be motorcycle race enthusiast. Rode (had a Kawasaki Z1-R) to Laguna Seca and watched Kenny Roberts a couple of times. When that guy was on top, he was on top. No one could touch him.
Good one and i agree best demonstration ive seen
Isn't that bag demo cool? I was blown away (no pun intended) when I first saw it.
@@swdweeb yes definitly. great way to easily show it
At long last! Measurements so we can reproduce it properly. Thank you!
I've offered a measured drawing and an stl file for over a year now free for download. All you had to do was ask. Sorry you didn't know. I would have gladly given you the measurements earlier.
@@swdweeb My apologies please, my comment came across SNOTTY, unintentionally. No longer have access to a 3D printer so making the tapered sprue on a wood lathe. Never thought to ask for measurments, shades of Wayne & Garth meeting Aerosmith.
Keep up the good content.
@@honthirty_ Ha! You'd think at my advanced age I'd think Wayne and Garth are stupid.. I can watch them over and over though 😃
No worries, I was really more concerned that I hadn't done a better job letting people know. I have a new square sprue debuting next week... assuming it works... that I'll make sure I post the dimensions for.
My first video of yours and I’m hooked for life 👍👍😊👍👍. Good thing I could subscribe so I don’t miss any future installments 😜. And that bell..... man this is great. Thanks for the very enjoyable lesson.
Man I need like 5,000 more just like you :-D Thanks!
Speaking of porosity, we got some replacement sub-floor vents cast in aluminium for one of the period buildings at the school I work at. The face of the casting was ok but the sides were filled with pin holes and this was from a professional foundry. Go figure!
Well, if you listen to Bob P, every foundry our there cast like that :-D
Should post a long to professor cambles book
Old Iron Shops : Dang you still alive? Thought either the flue or the wild fires got you. I know this is your busy season but How about posting every now and then so we know you're all right
@@CraigLYoung I know 😁 . I've been so busy hopping to get back on the horse again soon .
Here's the title "Mini Casting Handbook" By JOHN CAMPBELL Its all over the place at various prices from reasonable to absurd.
@@swdweeb already ordered it thanks
@@OldIronShops I hope you found it at a good price. I saw some insane prices out there
I wanted to do a cast with a tapered sprue since I started sand casting, but I still have no proper sprue pattern. (got a tapered pattern from an empty sew yarn roll, but that is a little short) With this information in mind, I really need to be on the look out for a proper sprue! Will defenitely improve my casts! I guess you need various diameters of sprues for different sized casts? For example, if I want to cast an aluminium cast of 3 kg, that small sprue will result in lack of liquid metal in my mold and causing freeze ups before it completely fills the mold right? I think when you go big, you need a bigger sprue and pouring cup, or am I completely wrong on this?
Have you thought about this www.plmfoundries.com/product-page/sprue-runner-kit
Brilliant!!
Ha! I love those guys. Back when men were men and commercials were funny 😃😃
Very informative, thank you and cheers from Italy!
( I have a request, how strong/stiff is cast alluminium compared to other metals? It would be a great video 😊)
That would be a good video. I know the different aluminum alloys exhibit different strengths. I've read that some are as string as steel. I'm not set up to do any of that kind of testing or reporting but it would be interesting. Ciao amici
@@swdweeb 😃
Thank you anyway for the lessons and the other videos, gonna buy the book you advised 👍🏻
@@pedgarage I'll let Professor Campbell know he sold another one 😃
Do you need different size sprues for different metals? Great demo !
I don't know that sprue size and metal type are directly related. If a metal needs to fill a mold quickly a larger sprue might be required. I'll have to ask. I just don't know.
I've use the same sprue for aluminum, brass and different bronzes
Acceleration due to gravity does not depend on material density. This is why a bowling ball and a feather will fall together in a vacuum. This has been done and is probably out on the TH-cams.
Troye Welch : It is understood that gravity is a constant, however this is a specific gravity question. If you are using different metals then the diameter of the sprue should change in order to maintain the desire flow rate,
Thanks for the info , very usefull :)
Thank you. Beautiful knife th-cam.com/video/jCX18YuG5B4/w-d-xo.html
Is that the same as the "bernoulli effect"?
Bernoulli or www.latimes.com/includes/projects/hollywood/portraits/valerie_bertinelli.jpg never quite sure 😃
I think this is bernoulli marineengineeringonline.com/operation-maintenance-eductor-ships/#:~:text=Eductor%20is%20a%20simple%20type,the%20ship%20including%20hazardous%20areas. but I'm just a meager software guy. 😃
You're more than just a bag of hot air. Interesting lesson. Tapered it shall be
You're right, I'm fat, old and ugly too :-D So let it be written. So let it be done.
I am curious about the relationship between the size of a part to be cast and the most appropriate sprue size. I recently cast a 9 pound part and after a few failures it seemed like a larger sprue helped completely fill the mold before the metal froze.
There are calculations... here's where you know I'll fall apart... that give you stuff like freeze rate and from there I expect you can figure out required volumetric flow rate. I know that larger castings require larger sprues for larger volumetric flow. I'll ask my foundry friend Nate if he's got anything to offer.
Preheating the molds before casting can reduce the risk of developing early freezing.
Nice. Makes more sense.
Thanks James, I'm really glad to hear that. Was it the bag or the water or both that made it more clear? Just curious.
Actually both made alot of sense.
Its funny how other people like adrock don't use the same Technique but everybody has their own style
@@jamesmartell8787 Thanks. I'm always curious what resonates with people
@@jamesmartell8787 Adam is a good friend and he does what works well for him. I cant argue with his success and I'm really happy for him. He's a good guy
Great info Perry, A+ lol
Thanks man
You made an aspirator or an eductor with your bag demo. The same principle is used to fill escape slides on passenger aircraft. The slides on an Airbus A380 have to inflate in under 2 seconds. They use a chemical rocket which fires through an open venturi to drag sufficient air to fill the slide and cool the rocket exhaust. A great demo and explanation but you almost lost me when you mentioned "mathematics". 😬
An eductor?? Come on Mark you hurt my little brain when you use big words like that 😃 I had to go look it up to see what it was, but yes apparently I did. 😃
Yeah, I'm pretty decent at arithmetic but that math stuff throws me every time. Had to call my son on how to move a variable from one side of the equation to the other. He said "come on dad you just divide both sides by the stuff you want to move" Sigh...
BRILLIANT!
Thanks 😄
You want to divide your flowrate ( length cubed per time) by the velocity (length) and that will give you the cross sectionla area (length squared) of the pipe ( not the diameter). You points are still good though, nice video!
sorry, i meant velocity (length per time)
Thanks, I appreciate the info. I'm really not a mathematician. If I think about it long enough it starts to make sense though
Got it
You guys are trying to sound fancy by using the word velocity instead of speed. The only difference is that velocity is speed with a direction. This only becomes important when you’re adding multiple vectored quantities together so you can add the separate components (x, y, and z, for example). Since we are talking about a vertical sprue with only a 1 dimensional component (z), the direction is implied and it’s not really a vector quantity in this context. Here, the word “speed” is fine... using “velocity” when “speed” would do only makes you sound smarter to people who don’t know any better (see the movie “Idiocracy”)
NOW. If you put the sprue in at an angle, you would have both a Z and an X/Y component. Gravity would only accelerate in the vertical direction, so the final speed (or velocity if you still want to go there) would be less for a given sprue length than a vertical one. This should make sense if you think about it. Further digging will reveal that it’s proportional to the cosine of the angle deviation from vertical (100% at 0 degrees deviation and 0% at 90 degrees)
Yeah I was just trying to say that what we're calling the size of the pipe is actually its cross sectional area and not the diameter...so the spreadsheet needs a sqrt() in it somewhere
A teacher affects eternity; he can never tell where his influence stops.
Wow! that's a great quote. Thank you
@@swdweeb no problem! Your videos are amazing, you have alot of knowledge about something I've always wanted to do but never had the money for the basic supplies. Your videos are inspirational! I can't believe you don't have over 100,000 subscribers
@@225dog3 Thank you so much. I'm not at 100K because most people want to be entertained, not educated. That's ok, I get it.
Would not a large feeder also allow inside air to be displaced, provide constant fluid feed and head pressure due to its weight? Can a small tapered sprue feed?
Can a small tapered sprue feed??? Of course it can feed.
Head pressure isn't all it's cracked up to be. th-cam.com/video/_3lwlBx6-YA/w-d-xo.html
Abd you certainly don't need a large feeder to displace air th-cam.com/video/fvSHwvTyApk/w-d-xo.html
Would this apply to vacuum assisted lost wax casting? I’m using a pretty large straight sprue. About 20mm in diameter. Each pour is about 9kg of brass.
Man, I'll be completely honest, I have never done any lost wax stuff. I marvel at the sculptures that come out of it all of the time. That said, know that everything I'm about to say is opinion based on zero experience doing what you do.
I think in general bottom filling and reducing the entrainment of air in the pour is a good thing. To that end, a tapered sprue that is kept full during the pour has to help with the amount of air that enters the mold. To what extent the vacuum helps with entrained air, I don;t know.
Sorry I wasn't more help.
swdweeb, this video was very helpful. Thought provoking. We actually fill from the top. During burnout the gate has to be at the lowest point of the casting so that the wax is able to completely empty the cavity. We already get very nice castings, but I think that a smaller and tapered sprue could be beneficial.
We often have up to 10 parts in one flask arranged around the sprue at varying distance from the mouth of the sprue. The vacuum certainly helps fill the cavities fully. The parts are either very ornate door handles or wiring channels that cannot be machined because features of the parts block access for a drill. The waxes are assembled from two parts so that the holes align.
Thanks again for the videos.
Like your videos i feel so at home
You live in a messy garage?? 😃😃 Thank you, I'm glad you feel that way,
@@swdweeb hahaha no i dont. But yeah. Our garage was actually sorted well kinda. Everything packed away by the helper now you need a search party if you want something.
@@frikkiesmit2695 I could have someone come in and organize, that would be great. Then I need someone to beat me over the head telling me to put stuff away after I'm done. 😃
If you were casting silver. Say items 1 to 2 oz. What scale would you print the sprue and spin trap?
Darn good question. It all comes down to how fast you need to fill the part. When you pour in a tapered sprue, its important to keep the sprue full the whole time. That means pouring as fast as it will take the metal. The smaller the sprue, the less metal you'll get to the runner. What is one ounce of silver, like a quarter (currency)?
@@swdweeb bigger than a quarter. An American Silver Eagle is a 1 troy ounce coin. It has a diameter of 40.6mm. It is 2.98 mm thick. So 1.598 inches across and .1173 inches thick.
@@swdweeb i am not sure why the latest comment didn't post. Just for perspective. I poured a silver lego. It was a 10 x 2 brick. It weighed 2 oz
@@billsaunders1879 Keep in mind, I've never poured silver. That said, I would think a part that small could use a smaller sprue than what I use but I'd probably still just pour it with what I have.
@@swdweeb thank you. I make coin rings. From 90% silver coins and also 999 fine silver bullion. I have to punch out the center before I make the ring. I have been saving my 999 fine silver punch outs to make castings with. I have been selling the 90% to local silver dealer. Apparently the 90% stuff is not was appealing to collectors and is harder to sell items cast from it. Lol I wish I had more 999 fine silver but I only have 6 oz right now. If the smaller spue and spin gate don't work then I will have to wait until I have more punch outs or possibly buy some bars with the money from the other scrap. I will let you know how it goes.
It seems logical that a tapered sprue would lead to less turbulence of the poured melt, and therefore less entrapped air. However the viscosity of the molten metal would not be the same as the viscosity of water, which would make your calculations dubious. Think of sucking honey compared to water through a straw. I suspect that your very nice casting has as much to do with the offset pouring basin, the spinner, the quality of the aluminium, the side-bottom feed and the quality of the mould. I imagine that molten aluminium has a higher viscosity than water, which would make the velocity of the melt even lower, and better, than your calculated value. But great food for thought. And thank you. I will try a tapered sprue!
The experts, Professor Campbell and Bob Puhakka all seem to treat the speed of the metal as if it is falling water. I've yet to read or hear them talk about the viscosity being an issue. I will ask Bob in my next conversation with him to see what he says.
I personally do not know the difference in viscosity between melted aluminum and water.
You are correct taht the quality of the casting has to do with all of those things. In the interest of keeping the videos brief, I cannot talk about all of the components together but none of them work without the other. It is a system.
If you watch a lot of aluminium pours the molten metal does behave almost the same as water only just a little bit slower. Some foundries pouring large quantities of aluminium direct the pour from the crucible to the molds via ceramic troughs almost like aquaducts. They have to preheat them first with a propane burner, but when the aluminium is released it is very much like watching water flow.
Mark Fryer “a little bit slower” is my point. I would like to know the number to see if the mathematics or arithmetic stacks up. The viscosity of molten aluminium and bronze would be relevant. I do not possess s copy of Prof Campbell’s book and cannot find the number elsewhere. Johnsmachines.com
Hiya. Flow control is worth an entire video. It makes or breaks a pour.
WE're getting there. Be patient :-D
Thank you for doing these Perry. Much appreciated. Like others here I imagine, I have been casting for a while, but I need to review the basics to try and correct my ongoing rookie mistakes. Shameless plug, I made a video a few weeks back inspired by the videos you hosted for your friend Bob Puhakka and also Andrew Martin's experiments. th-cam.com/video/GwqENPFqPBM/w-d-xo.html. Also, would you consider doing a basics lesson on sand management? I pull my hair out trying to guess at the right moisture content to maintain. Thanks again.
Shamelessly plug yourself all you want. I watched both videos. Good stuff.
Regarding sand, that's a tough one. I thought I put a really quick spot in one of the "learning" videos but I couldn't find it so I guess it ended up on the cutting room floor as it were. It really is a trial and error thing for me. I have settled on a ratio of about 2 liters of sand and 36ish ml of water for my ratio. I have a cup that holds about 400ml of sand and a little cap that holds about 6ml of water. I mix five cups of sand with 6 caps of water.
I let my sand dry out between uses. That does two things. It gives me a consistent starting point for how much water and it keeps it from developing a moldy smell to it. I'm the only one that I know of that seems to get that smell, but I don't like it so I let it dry out. The downside to this is I have to prepare my sand before I cast anything. When you just want to run out there and cast and think "Doh... I've got to make sand first" it can be a bit of a discouragement.
Bottom line on the sand is I've found a moisture content that seems to work well for me and now I know what it feels like. So I can stick my hand in it and tell if its too wet or dry. I've kinda forced myself to do it that way as I want to be able to simply grab some sand know that its where I want it to be
@@swdweeb Thanks for the reply. I like your consistent approach, but having to re-wet sand every time goes against my lazy nature. I think I might try drying out a portion as a test and then adding in water with the ratio you mentioned.
@@charliekrauter5176 trust me, I wish I could just store sand that was ready to go and use it whenever I want too :-D I tried that and as I said it smelled of mold when I opened the container. Probably because it was moist and sealed and in a garage that gets to around 100F in the afternoons.
I know other people are able to store their sand in sealed containers so they only have to go through the re-wetting occasionally and do it in large batches. Just didnt work for me.
Good luck with it. You will likely find "your mileage will vary" on the amount of water but play with it and get it to where you like it.