Back in 1967, Max Evans Motorcycles, or Caringbah Motorcycles, Captain Cook Drive Taren Point Sydney had 3 Walsh styled heads just like the one you have sitting, gathering dust on the top shelf behind the front counter. I was 13, a Bantam owner, and knew what they were, but the old man said it was a complete waste of time and money to put one on my worn-out '54 Plunger. They were probably sold as scrap when Max moved on. Great video, good luck with the next one and put a bloody respirator on, I've just been diagnosed with Pulmonary Fibrosis, 54 years in the building trade which has cut my life short.
Comments about needing vents are probably by people who have never done lost foam casting. I'm sure they are suggesting this based on lost way casting, something very different. With lost way casting the model and the vents are burnt out before the pour. That is not the case for lost foam. Any vent channels would still be filled with foam. Lost foam relies on the plaster to be porous to gas so that it escapes to the unbounded sand. I think that your aluminum was too cold. It seemed to me that the fins were too thin. Not just from a pouring standpoint but also from a heat transfer perspective in the final application. (hard to tell the actual thickness from the video. I think that it would have filled better if the part was tilted somewhat, so the fins were faced down a little. What also could help (but more involved) is to have the bucket holding the sand under partial vacuum (vacuum assist) to help pull the gasses through the plaster. I did skip some parts in the video so I don't know what you were using for plaster. If it was meant to do lost foam casting. If what you used had enough permeability. On pouring, you never want interrupted pours. The burp and flame caused the expected reaction of self preservation. Startling when not prepared for it. As far as PPE, I would also include a cap to cover the top of the head. Just in case something spits up and comes down on your heads. Chances are low but not zero. I also thing a proper set of lifting tongs would be good to have. You want to support the crucible when lifting out of the furnace. With the tongs you are using you have little surface contact and are squeezing at the weakest part of the crucible. Something like this style is better. i.ebayimg.com/images/g/PsIAAOSwVu5jqXOP/s-l1200.jpg
Hi .....I really appreciate your constructive comments. There are a few technique issues that will be addressed in the next pour. The pattern had knife edges on the fins caused by a cutter that wasn't sharp enough and incorrect speed and feed rate on the CNC. Metal has been addressed with a thermocouple on board now. I've made up a test piece to pour with thicker fins plus sprue and gates orientated as per Kelly's advice. The refractory coating was topcoat plaster slurry, however I think I layered it too thickly which prevented it gassing out into the sand and instead sent it back up the sprue. Yes I do have to make some lifting tongs however there isn't much weight in the crucible.........Next pour hopefully this weekend.......Stay tuned!
Very interesting.....I remember when I started scuba diving 45 years ago.....getting clay from an excavation site. To use for a mould....it worked ok.....but showed me these things are not easy.....I take my hat off to you Tony. From Nick a B175 Bantam owner in the UK.
Hi Mate.........Yes I think this is the way to go. I'm lining up for another pour next weekend.........I don't think I'm far away now.........Well I hope not anyway.
I have just played a little bit with lost foam and lost 3D printed pla. a really thin coating of plaster of Paris on the foam and it made for a very smooth casting.Maybe that would help with the thin fins. Best of luck to you! Keep it up!
When casting, especially with foam which will gassify as it burns away, you must have additional vents to allow the gas to purge. you were lucky the molten aluminium didn't plume out violently. Do please be careful.
Go and watch some of Kelly Coffield's YT lost foam casting videos...........Then get back to me about how many vents he has. No offence, but you're not to clued up on the lost foam casting process...........Neither are a lot of others.
When I used to lost form cast we were taught to have a runner (to pour into) and a small open riser to let gas out. Nice job though, get the temperature right at the gas out, should be sweet.
A German company doing castings would have poured the material, be it steel or aluminium into a trough and let it fill the mould from below. I saw many casting made this way and witnessed dye penetrant testing after the casts had cooled, very rarely were there defects.
Thanks Mate. Just finished tapping out an email to Dean! Yes we are getting close......I'm fairly confident for the next pour which will hopefully be this weekend. I happy things are progressing and am fairly confident of the cause of faults thus far.
One idea I had is where there are those 4 circles on the head mold where I assume holes will be drilled for head studs, you could put little "spot drill" divots so you have something on the casting to locate the center points of the holes. Or maybe that operation is trivial.
The lost foam isn't done in green sand is to vent out through the refractory into the dry sand. Have a look at Kelly Coffields casting videos. My sprue was too large on entry into the pattern and didn't allow the head pressure of the metal to force the gases out into the sand. Thanks for commenting I appreciate it.
Another great video mate, really interesting watching your progress 👍 To reduce the video flicker try recording at 25 FPS, I believe you guys use 50Hz mains like us here in the UK.
Uh, first “tapered end mill” I got was for a tool called a “roto-zip” - and was a lot finer-toothed than the more-usual tapered end mills I’ve purchased later.
Yes, probably too cold. Without a way to measure metal temp you're just guessing. With the thin fins, I'd probably shoot for 1375F. The sprue size looks fine but could be narrowed where it contacts the pattern. This will somewhat slow the fill rate, surge of metal flow, and flashback at the cup. It will also make it easier to degate. If you make your pouring cup have larger volume, it will provide more of a buffer to ensure a continuous pour, preferably square with the sprue offset to one side. You need to bury the cup to near the top, so the metal pressure doesn't cause the metal leak at the bottom of the cup. Best, Kelly
Hello Kelly and thanks for posting all your videos.........I watch them a lot! Thermocouple is on it's way. Would you do a gating system a bit like your 4 cylinder model aircraft engine where you could transition the sprue into say four 10mm entry points to the casting? The next pouring cup will be larger and moulded in the same profile as yours (and Ol Foundryman) I would have done it for the last pour but got a bit time constrained. I noticed in your "finned" barrels video that they were set on angles. Does the orientation of the pattern make a difference? If so what would you recommend. I have been conversing with Ol Foundryman who has been a great help as well. I really appreciate you taking the time to comment and offer advice..........regards Bones
@@OzBSABantams I'd gate it like you have, the length of the bottom side, but as previously mentioned, reduce the contact area from the sprue/runner. You might also slightly taper the runner along the length of the pattern. Splitting the runner into two similar (smaller) runners spaced apart will reduce the distance the metal must travel before it freezes. It will reduce pour/fill time and allow slightly cooler pour temps for and/or more complete fill for thin features. The two runners need to be connected with a Y. I sort of doubt this is necessary for your part bu these type of feed systems can really take metal fast once they penetrate the pattern so ample cup volume (>30% casting weight) is very helpful. It's a longer discussion but a slight (say 15 to 30 degrees) angle as opposed to vertical orientation can help results. Fins down probably helps with them fill a little better, fins up pack better, but if you have any porosity, it will be present near the surface on the side that faces upward due to buoyancy. I often don't have this luxury of tilting the pattern because of limitations of flask size but it is most helpful to help fill internal cavities. Best, Kelly
Great to see Kelly on here Some local experience here in qld is the use of the slurry you have with added acrylic paint as a thinning medium to help apply the slurry. This suggestion came from a TH-camr who is casting loudspeaker frames. Quote th-cam.com/video/jFoeOQUVqRs/w-d-xo.html @10luciano1000 4 years ago If you make a very neat foam model and give it 3 coats of paint, and let it dry well between coats, the painting is done with plaster, latex wall paint and water so that it looks like cream soup and you color it with stamp ink to see where you are painting because the foam is white, you can also use latex wall paint of any color other than white, and the container where you put the model in sand will vibrate very well, it will be perfectly finished and the support of the how can you machine it with a router Local experience is also to use silica (water glass) set cores in places which may distort during the sand packing process - probably not needed here. He was making rocker covers for his mini cooper. All in all you look to be very close
Looks like you need some help. I have tried this numerous times, I was getting very close after ~ a dozen times, changing things to de-gassing and gave up! That is what you should do, face the music and go green sand and split mold, that is how it was made. I'm going to be short, because seems no one listens to me, contact me if you have questions. Bentonite clay, sharp sand, and locking boxes. I would first attempt it by cleaning the head really clean and rub baby powder into the surfaces, then sprinkle more powder, and pack the sand. The next way is to make it out of Maple wood, make it smooth, and seal it, smooth it again, powder, then pack the sand. With all those fins, I would put in lots of Bentonite and let the two halves sand forms dry before pouring. Sometimes, one has to admit that this is the wrong road. But, I still get drawn it, hoping someone has really figured out lost foam.
You need to put a riser and pourer in a mould - use a skewer to add a multitude of vents - George Tod made heads like that in the 70's - you would have more luck with lost wax and wet dip
Yes you need a pourer and riser with green sand moulding (look at the video where I did that) where the sand is bonded. Lost foam uses unbonded dry sand. There are a few technique improvements for the next pour. Thanks for commenting......
Foam's a fair amount more delicate than the bits of stringing that 3d printing can leave on detailed prints, but for those I actually use a lighter I wash over the print real quick. Idea might work for foam, though you might want a heat gun instead of open flame? Honestly you're making it work so more power too you, but thought I'd throw the idea out *shrugs*
Lost foam is trash. Make a plastic epoxy mold and then cast wax castings. And do lost wax in the sand. When you pour do it so the fins are down, and make sure you have a vent tube not just a pour tube.
Then I'd have to do a negative mold and have a pattern to do that. Cook the wax out ( I don't have a kiln) Much easier doing lost foam . I appreciate your comments...........
@@hotrodZack1948 I wouldn't rule that out, however my green sand isn't up to scratch to do the job, it's too coarse and gives a poor finish. Also the pattern I used needs some more work if I were to use it again.......I'll keep persisting with lost foam for the time being. Thanks for commenting.....
Yes and no. If you wanted to CNC it you still have to write a program. What I'm trying to achieve is a replica type head so I really want a casting look and finish.
I have neither expertise nor experience in lost foam casting but is it possible that cavitation is occuring because gases can't escape during pouring? I know you have the central stem but as half of the head is actually above that escape route how and where are the gases supposed to escape? They want to rise upwards but there's no way out. They expand until the pressure is great enough to push downwards through the molten aluminium so they can escape but the metal is already starting to cool down. If the pressure isn't great enough to penetrate the cooling metal it will be trapped in situ and leave imperfections in the casting. I might just be an idiot so ignore me if I'm talking rubbish.
No it's an OK theory.........The gases escape through the refractory into the sand. The sand isn't packed and is porous. My issue was the sprue wasn't tapered enough and the gases had an escape route back up the sprue. I think my refractory coating may have been too thick as well which didn't allow the gasses to escape well enough too.. Thanks for commenting
In lost foam casting the gases vent through the refractory into the sand..........there are no vents like sand casting. Wax casting would also require a negative mould which i don't have. thanks for offering advice......It's appreciated.
@@tonydoggett7627 The only issue is I don't have a kiln to do the melt out. The "wax"needs a fair temp to do the melt out. I have looked into it. Thanks for commenting.
Tony, do you think heating the whole mold steadily over a flame (bucket and all over a burner for an hour or so) to raise the temp would help the casting process? Surely an extra 60-70 degrees would prevent rapid cooling of the molten aluminium and help fill the finer voids and extremities? Can't hurt to try.
Thanks for commenting..........No I think my issue is guessing the material temperature instead of measuring with accuracy has a big part to play, plus the foam part had the fins too thin of a section to fill. Add to that my refractory coating was too thick to allow the gasses to escape into the sand. So knowing all that now I'm hoping the next pour will go better. I might add the people machining the pattern have never done foam before so they are on a learning curve like me too............
@@silverfox57 yep they do need vents for sand casting........I worked in a foundry too. This is lost foam casting where the sand isn't packed like a mould and the gasses vent through the refractory coating into the dry sand so you don't use vents.
None.........But I'm trying to replicate an engine built in the 1950's so a billet machined head would look totally out of place on the engine...............
It's lost foam casting......the sand is supposed to be dry. You don't use vents as the gases vent out through the refractory into the sand. Co2 activated sand for cores and green sand moulds that do have vents/risers etc..........
@@OzBSABantams incorrect Didn't you notice when the aluminum came back up and spilled over like a baby puking? That's the foam gas escaping the only way it can .... I used oil sand and put a few vents in with the riser hollow and a sump with a mesh to stop sand ingress also the part was flat not vertical which is another mistake Hey it's all a learning curve I'm just trying to help
@@gearsandtears7643 The issue I had was I did the refractory coating too thick which prevented the gasses venting out through it causing it to vent back out the pourer. Sprues were parallel which meant the head pressure of the molten metal didn't force the gasses through the refractory. The part was vertical when poured........All and any input is welcome. Thanks for commenting
@@gearsandtears7643 That would be fine and reasonably easy for someone like me..........But it misses the point of trying to replicate the cast head and engine.
Back in 1967, Max Evans Motorcycles, or Caringbah Motorcycles, Captain Cook Drive Taren Point Sydney had 3 Walsh styled heads just like the one you have sitting, gathering dust on the top shelf behind the front counter. I was 13, a Bantam owner, and knew what they were, but the old man said it was a complete waste of time and money to put one on my worn-out '54 Plunger. They were probably sold as scrap when Max moved on. Great video, good luck with the next one and put a bloody respirator on, I've just been diagnosed with Pulmonary Fibrosis, 54 years in the building trade which has cut my life short.
Thanks for commenting.
Comments about needing vents are probably by people who have never done lost foam casting. I'm sure they are suggesting this based on lost way casting, something very different. With lost way casting the model and the vents are burnt out before the pour. That is not the case for lost foam. Any vent channels would still be filled with foam. Lost foam relies on the plaster to be porous to gas so that it escapes to the unbounded sand.
I think that your aluminum was too cold. It seemed to me that the fins were too thin. Not just from a pouring standpoint but also from a heat transfer perspective in the final application. (hard to tell the actual thickness from the video. I think that it would have filled better if the part was tilted somewhat, so the fins were faced down a little.
What also could help (but more involved) is to have the bucket holding the sand under partial vacuum (vacuum assist) to help pull the gasses through the plaster. I did skip some parts in the video so I don't know what you were using for plaster. If it was meant to do lost foam casting. If what you used had enough permeability.
On pouring, you never want interrupted pours. The burp and flame caused the expected reaction of self preservation. Startling when not prepared for it. As far as PPE, I would also include a cap to cover the top of the head. Just in case something spits up and comes down on your heads. Chances are low but not zero.
I also thing a proper set of lifting tongs would be good to have. You want to support the crucible when lifting out of the furnace. With the tongs you are using you have little surface contact and are squeezing at the weakest part of the crucible. Something like this style is better. i.ebayimg.com/images/g/PsIAAOSwVu5jqXOP/s-l1200.jpg
Hi .....I really appreciate your constructive comments. There are a few technique issues that will be addressed in the next pour. The pattern had knife edges on the fins caused by a cutter that wasn't sharp enough and incorrect speed and feed rate on the CNC. Metal has been addressed with a thermocouple on board now. I've made up a test piece to pour with thicker fins plus sprue and gates orientated as per Kelly's advice. The refractory coating was topcoat plaster slurry, however I think I layered it too thickly which prevented it gassing out into the sand and instead sent it back up the sprue. Yes I do have to make some lifting tongs however there isn't much weight in the crucible.........Next pour hopefully this weekend.......Stay tuned!
I think adding a riser or two may help along with a bigger runner and pouring bowl
Thanks for taking one for the team. Cheers from So.Ca.USA 3rd House On the Left
Very interesting.....I remember when I started scuba diving 45 years ago.....getting clay from an excavation site.
To use for a mould....it worked ok.....but showed me these things are not easy.....I take my hat off to you Tony.
From Nick a B175 Bantam owner in the UK.
Thanks.......
I've watched a lot of Kelly C's videos and wondered how hard it is to do ( lost foam) . Leaning from your journey. Thanks.
You are definitely on the road with this. You've come a long way already. The lost foam process seems much more promising.
Best wishes, Dean.
Hi Mate.........Yes I think this is the way to go. I'm lining up for another pour next weekend.........I don't think I'm far away now.........Well I hope not anyway.
@@OzBSABantams I think you are onto something. Good luck with the next pour.
I have just played a little bit with lost foam and lost 3D printed pla. a really thin coating of plaster of Paris on the foam and it made for a very smooth casting.Maybe that would help with the thin fins. Best of luck to you! Keep it up!
Slurry for the win, yes!
Thanks mate.........
When casting, especially with foam which will gassify as it burns away, you must have additional vents to allow the gas to purge. you were lucky the molten aluminium didn't plume out violently. Do please be careful.
💯 needs to vent as he thinks it will vent through the sand which is impossible with the coating on the foam
Go and watch some of Kelly Coffield's YT lost foam casting videos...........Then get back to me about how many vents he has. No offence, but you're not to clued up on the lost foam casting process...........Neither are a lot of others.
Nice video coming along quite well. I like Myfordboy for TH-cam casting videos. Very informative
Yes I agree.........I have been watching a bit of his stuff.
Nice going mate. Well on the way to what you're looking for. Always enjoying your videos.
Cheers, Peter.
Thanks 👍
When I used to lost form cast we were taught to have a runner (to pour into) and a small open riser to let gas out. Nice job though, get the temperature right at the gas out, should be sweet.
Thanks 👍
Maybe an open riser at each outer edge of the pattern to get full gas escape.
A German company doing castings would have poured the material, be it steel or aluminium into a trough and let it fill the mould from below. I saw many casting made this way and witnessed dye penetrant testing after the casts had cooled, very rarely were there defects.
Absolutely brilliant, thoroughly enjoyed it. Looks like you have the right process, now it's ",just" a case of refining it!
Thanks Mate. Just finished tapping out an email to Dean! Yes we are getting close......I'm fairly confident for the next pour which will hopefully be this weekend. I happy things are progressing and am fairly confident of the cause of faults thus far.
One idea I had is where there are those 4 circles on the head mold where I assume holes will be drilled for head studs, you could put little "spot drill" divots so you have something on the casting to locate the center points of the holes. Or maybe that operation is trivial.
No it could be done. However depending on what barrel I fit the head to may dictate the hole centres as they are different PCD's....
As a x foundry man I would added some vents to let the gases escape
The lost foam isn't done in green sand is to vent out through the refractory into the dry sand. Have a look at Kelly Coffields casting videos. My sprue was too large on entry into the pattern and didn't allow the head pressure of the metal to force the gases out into the sand. Thanks for commenting I appreciate it.
Another great video mate, really interesting watching your progress 👍 To reduce the video flicker try recording at 25 FPS, I believe you guys use 50Hz mains like us here in the UK.
Thanks for the tip!
Uh, first “tapered end mill” I got was for a tool called a “roto-zip” - and was a lot finer-toothed than the more-usual tapered end mills I’ve purchased later.
I appreciate the tip..........
If you got the 3d model i think a much better result can be had with lost PLA from a 3d printed model.
I don't have an oven to do the burnout
I also think it wasn’t up to temperature. I also wondered if the originals might have been centrifugally cast?
Yes, probably too cold. Without a way to measure metal temp you're just guessing. With the thin fins, I'd probably shoot for 1375F. The sprue size looks fine but could be narrowed where it contacts the pattern. This will somewhat slow the fill rate, surge of metal flow, and flashback at the cup. It will also make it easier to degate. If you make your pouring cup have larger volume, it will provide more of a buffer to ensure a continuous pour, preferably square with the sprue offset to one side. You need to bury the cup to near the top, so the metal pressure doesn't cause the metal leak at the bottom of the cup. Best, Kelly
Hello Kelly and thanks for posting all your videos.........I watch them a lot! Thermocouple is on it's way. Would you do a gating system a bit like your 4 cylinder model aircraft engine where you could transition the sprue into say four 10mm entry points to the casting? The next pouring cup will be larger and moulded in the same profile as yours (and Ol Foundryman) I would have done it for the last pour but got a bit time constrained. I noticed in your "finned" barrels video that they were set on angles. Does the orientation of the pattern make a difference? If so what would you recommend. I have been conversing with Ol Foundryman who has been a great help as well. I really appreciate you taking the time to comment and offer advice..........regards Bones
@@OzBSABantams I'd gate it like you have, the length of the bottom side, but as previously mentioned, reduce the contact area from the sprue/runner. You might also slightly taper the runner along the length of the pattern. Splitting the runner into two similar (smaller) runners spaced apart will reduce the distance the metal must travel before it freezes. It will reduce pour/fill time and allow slightly cooler pour temps for and/or more complete fill for thin features. The two runners need to be connected with a Y. I sort of doubt this is necessary for your part bu these type of feed systems can really take metal fast once they penetrate the pattern so ample cup volume (>30% casting weight) is very helpful. It's a longer discussion but a slight (say 15 to 30 degrees) angle as opposed to vertical orientation can help results. Fins down probably helps with them fill a little better, fins up pack better, but if you have any porosity, it will be present near the surface on the side that faces upward due to buoyancy. I often don't have this luxury of tilting the pattern because of limitations of flask size but it is most helpful to help fill internal cavities. Best, Kelly
Great to see Kelly on here
Some local experience here in qld is the use of the slurry you have with added acrylic paint as a thinning medium to help apply the slurry. This suggestion came from a TH-camr who is casting loudspeaker frames.
Quote
th-cam.com/video/jFoeOQUVqRs/w-d-xo.html
@10luciano1000
4 years ago
If you make a very neat foam model and give it 3 coats of paint, and let it dry well between coats, the painting is done with plaster, latex wall paint and water so that it looks like cream soup and you color it with stamp ink to see where you are painting because the foam is white, you can also use latex wall paint of any color other than white, and the container where you put the model in sand will vibrate very well, it will be perfectly finished and the support of the how can you machine it with a router
Local experience is also to use silica (water glass) set cores in places which may distort during the sand packing process - probably not needed here. He was making rocker covers for his mini cooper. All in all you look to be very close
Some usefull info from NZ on making foam patterns and casting
th-cam.com/video/4DC0h8UHPak/w-d-xo.html
@@jirvin4505 Thanks for commenting and providing more insight into the process........I appreciate it.
You’re pour height could be shorter then a vent out would make a fluid circuit
Looks like you need some help. I have tried this numerous times, I was getting very close after ~ a dozen times, changing things to de-gassing and gave up! That is what you should do, face the music and go green sand and split mold, that is how it was made. I'm going to be short, because seems no one listens to me, contact me if you have questions. Bentonite clay, sharp sand, and locking boxes. I would first attempt it by cleaning the head really clean and rub baby powder into the surfaces, then sprinkle more powder, and pack the sand. The next way is to make it out of Maple wood, make it smooth, and seal it, smooth it again, powder, then pack the sand. With all those fins, I would put in lots of Bentonite and let the two halves sand forms dry before pouring. Sometimes, one has to admit that this is the wrong road. But, I still get drawn it, hoping someone has really figured out lost foam.
thanks for your input. I've already cast a head in sand...........watch my earlier videos.
I'm sure you will crack it mate
You need to put a riser and pourer in a mould - use a skewer to add a multitude of vents - George Tod made heads like that in the 70's - you would have more luck with lost wax and wet dip
Yes you need a pourer and riser with green sand moulding (look at the video where I did that) where the sand is bonded. Lost foam uses unbonded dry sand. There are a few technique improvements for the next pour. Thanks for commenting......
Foam's a fair amount more delicate than the bits of stringing that 3d printing can leave on detailed prints, but for those I actually use a lighter I wash over the print real quick. Idea might work for foam, though you might want a heat gun instead of open flame? Honestly you're making it work so more power too you, but thought I'd throw the idea out *shrugs*
Thanks for commenting and offering up your suggestions. Any and all input is welcome.........
Lost foam is trash. Make a plastic epoxy mold and then cast wax castings. And do lost wax in the sand. When you pour do it so the fins are down, and make sure you have a vent tube not just a pour tube.
Then I'd have to do a negative mold and have a pattern to do that. Cook the wax out ( I don't have a kiln) Much easier doing lost foam . I appreciate your comments...........
You dont have to cook the wax out you just pour the metal and the wax goes away same as foam
You could also do as before with just the bare sand mold use finer better quality greensand. Pour it hot with the fins down.
@@hotrodZack1948 I wouldn't rule that out, however my green sand isn't up to scratch to do the job, it's too coarse and gives a poor finish. Also the pattern I used needs some more work if I were to use it again.......I'll keep persisting with lost foam for the time being. Thanks for commenting.....
Stupid question maybe but would it not be easier to machine the head from a solid block of ali?
Yes and no. If you wanted to CNC it you still have to write a program. What I'm trying to achieve is a replica type head so I really want a casting look and finish.
without a CNC mill cutting the fins would be very time consuming!
I have neither expertise nor experience in lost foam casting but is it possible that cavitation is occuring because gases can't escape during pouring? I know you have the central stem but as half of the head is actually above that escape route how and where are the gases supposed to escape? They want to rise upwards but there's no way out. They expand until the pressure is great enough to push downwards through the molten aluminium so they can escape but the metal is already starting to cool down. If the pressure isn't great enough to penetrate the cooling metal it will be trapped in situ and leave imperfections in the casting. I might just be an idiot so ignore me if I'm talking rubbish.
No it's an OK theory.........The gases escape through the refractory into the sand. The sand isn't packed and is porous. My issue was the sprue wasn't tapered enough and the gases had an escape route back up the sprue. I think my refractory coating may have been too thick as well which didn't allow the gasses to escape well enough too.. Thanks for commenting
Do an investment casting with a wax model melted out. The mould must have a vent
In lost foam casting the gases vent through the refractory into the sand..........there are no vents like sand casting. Wax casting would also require a negative mould which i don't have. thanks for offering advice......It's appreciated.
@@OzBSABantams 3D wax print
@@tonydoggett7627 The only issue is I don't have a kiln to do the melt out. The "wax"needs a fair temp to do the melt out. I have looked into it. Thanks for commenting.
Tony, do you think heating the whole mold steadily over a flame (bucket and all over a burner for an hour or so) to raise the temp would help the casting process? Surely an extra 60-70 degrees would prevent rapid cooling of the molten aluminium and help fill the finer voids and extremities?
Can't hurt to try.
Thanks for commenting..........No I think my issue is guessing the material temperature instead of measuring with accuracy has a big part to play, plus the foam part had the fins too thin of a section to fill. Add to that my refractory coating was too thick to allow the gasses to escape into the sand. So knowing all that now I'm hoping the next pour will go better. I might add the people machining the pattern have never done foam before so they are on a learning curve like me too............
I've had good results using plaster of paris.
Maybe a vent for the cast would of been a good idea...
Lost foam doesn't require vents.......It vents through the refractory into the sand...
I used to work in a foundry making the sand for the moulds. All the moulds had vents even the small ones.
Whether it was for iron or alloys.
@@silverfox57 yep they do need vents for sand casting........I worked in a foundry too. This is lost foam casting where the sand isn't packed like a mould and the gasses vent through the refractory coating into the dry sand so you don't use vents.
And that is why there is casting flow marks on the head as the gasses cant escape quick enough.
@@silverfox57 That's right.........Which meant my refractory coating was too thick to vent the gasses.
Is there any reason why this part cannot be machined out of a billet of aluminum?
None.........But I'm trying to replicate an engine built in the 1950's so a billet machined head would look totally out of place on the engine...............
Maybe plaster would work better?
Close but no cigar.
You didn't vent it.
You don't vent lost foam casting.........It vents into the sand through the refractory.
Warmer metal, more ingates
You probably have Styrofoam impurities in your casting.
How is this caused?
@@OzBSABantams This is unlikely and easy to check by cutting the failed casting.
Sand too dry and no vents for the smoke to escape if you use different sand with CO2 activation you will have better luck
It's lost foam casting......the sand is supposed to be dry. You don't use vents as the gases vent out through the refractory into the sand. Co2 activated sand for cores and green sand moulds that do have vents/risers etc..........
@@OzBSABantams incorrect
Didn't you notice when the aluminum came back up and spilled over like a baby puking? That's the foam gas escaping the only way it can .... I used oil sand and put a few vents in with the riser hollow and a sump with a mesh to stop sand ingress also the part was flat not vertical which is another mistake
Hey it's all a learning curve I'm just trying to help
@@gearsandtears7643 The issue I had was I did the refractory coating too thick which prevented the gasses venting out through it causing it to vent back out the pourer. Sprues were parallel which meant the head pressure of the molten metal didn't force the gasses through the refractory. The part was vertical when poured........All and any input is welcome. Thanks for commenting
@@OzBSABantams such a simple head I'd sooner machine a block of aluminum you could cast the combustion shape and mill the fins your own design
@@gearsandtears7643 That would be fine and reasonably easy for someone like me..........But it misses the point of trying to replicate the cast head and engine.