EASY build Vacuum Casting machine system for Lost Wax / PLA Casting – DIY chamber & Pump : lwc #6


Hi YouTube, my name’s Geoff and I’m the
VegOilGuy. If you’ve been watching my videos lately,
you’ll have seen my ongoing battle with Lost Wax Casting.
The one persistent comment I’ve had since trying starting this is “use a vacuum.”
Some of you have even been observant enough to say, “Hey, you’ve got a vacuum pump.
Why aren’t you using it?” Well this pump cost me a lot of money… more
than I wanted to spend in honesty. And whilst it’s very good, it cannot be exposed to
heat… and molten metal is pretty hot. So I wondered if I could make my own vacuum
system… and that’s what I’ll be doing today.
I started out with a couple of purchases, and a big thanks to those contributors who’ve
been kind enough to make donations. It really is a big help.
I bought this solid stainless steel flask. It was a fifth of the price of the perforated
flasks so I thought I’d give it a go. I also bought this injection wax, and it’s
brilliant. Honestly… I can’t praise it enough.
If you saw the very first casting challenge, you’ll remember I tried to cast a coin and
this is the silicone mould I made. However, the wax coins I produced were far
from ideal. But things were different with this wax.
I poured some of the pellets in an empty food can and heated them gently on this electric
hob until they’d melted. Then I placed a plastic syringe inside to acclimatise. The
wax isn’t hot enough to melt the syringe but if the syringe isn’t pre-heated the
wax will freeze instantly. After a few minutes, a small amount of wax
is drawn up the syringe and then injected into the mould. It’s important not to pull
the syringe out too quickly, but to give the wax a few seconds to begin to solidify.
A few minutes later, the mould was opened up and look at that. What an amazing wax pattern.
This was my first ever try with this wax and I can’t fault it. I think these horizontal
lines are caused by the force of the syringe. It’s too large really. A smaller syringe
would have been more controllable. And if you’re wondering what all the other lines
are, they’re tool marks. This mould was made from a 3D print and I wanted to keep
these marks – I wanted to test the ability of wax casting to pick up very fine detail.
I decided to try this injection wax as a pouring wax. Even in an open mould, without any fuss,
it produced beautiful results. Yes, I could have taken more time and got something a little
better, but for today’s experiment, these will do, especially if we remember exactly
what these faults were. I was so impressed with this wax that I honestly
didn’t want to introduce another sort, so I made a few crude sprues from this wax and
made a wax tree. With the tree on an old tin lid, the steel
flask slides over with too much room to spare if I’m honest. But better too big than too
small. I surrounded the base with plasticine, or
modelling clay, whatever you call it, as this makes it water tight.
I then mixed up some investment plaster, mixing this well for around 3 minutes in line with
the manufacturer’s instructions. I then vacuumed this is my vacuum chamber to remove
excess air, poured the content into the tube, and discovered I hadn’t quite mixed up enough.
Typical. But this stuff goes off too fast to mess around
so I turned on my vacuum pump and removed any air that had become trapped during the
pour. After it had set, around 10 minutes later, I topped off with a little more plaster
to make sure everything was covered. Two hours later, I pulled the plasticine from
around the rim, scraped away any loose plaster, then gently prized the wax from the lid. I
love the way it had captured the ink from the barcode beneath it.
This was then placed in my foundry at 80°C for an hour to gently cook out the wax.
A few weeks ago, I shared with you a homemade vacuum chamber, made from cheap plumbing parts
and bits of plywood. I wondered if I could use this to vacuum molten metal. Well there’s
no way I could place a red-hot flask inside a wooden box, but maybe I could place one
on top… I took the clear plastic lid and cast a silicone
circle on top of this. Silicone is actually pretty good with heat and can withstand up
to around 300°C without fuss. I drilled a small hole centrally and planned
not to lift the silicone. But the debris from the drill got stuck beneath this so I had
no choice, though this type of silicone doesn’t like sticking to anything, so lifting it was
easy. I cleared the dust and re-aligned everything.
Now I had somewhere that I could place the flask.
I grabbed the hand-made piston pump I created at the same time as the Vacuum Chamber, and
I hooked this up. I placed a food can on top of the silicone pad and got pumping.
Almost immediately the gauge started to register the vacuum, and when I tried to lift the food
can free, it was stuck firmly thanks to the power of the vacuum.
It’s worth noting that this vacuum chamber has sprung a leak. Over around 20 seconds
or so it will lose vacuum. Whether this is the silicone seal, the valves or the plumbing
I just can’t be sure as it’s so small a leak I can’t detect it. But it does mean
extra pumping to maintain the vacuum. Additionally this chamber is around 8 inches
square inside and whilst it’s quick enough to empty of air, it could make it quicker.
So I came up with a simple solution. This is my lazy bucket. When I’ve finished
casting I tend to throw in bits of plaster, metal and other debris left over from my tinkering’s.
I always keep my McDonalds drink cartons as they make useful mixing cups, and four of
these would be ideal for my next idea. I gathered the plastery debris and added some
water to this as I knew it would be thirsty for moisture. After a few minutes, I poured
away the excess water, leaving a sludgy mess. I then mixed up some very watery plaster of
Paris. A little Plaster of Paris goes into the cup.
Then it’s mostly filled with debris. Then I topped off with more Plaster of Paris and
tapped everything to settle out the content. Strange how it looks like a McDonald’s milk
shake. These set within half an hour and four of
these fill my vacuum chamber. This drastically reduces the airs I need to displace.
With the lid on and a paint tin on the silicone pad, a quick pump test showed a much faster
response. It was now ready to try with metal. Now, a couple of important points…
Firstly, the plaster flask was cooked according to the manufacturer’s instructions, but
this time I raised it to 700°C. I then took this out of my foundry and covered it with
fire bricks allowing it to cool, but slower than it would have done.
Secondly, a few of you guys have been asking about my metal preparation. So just to clarify,
I heat my metal thoroughly and remove any dross. I then add de-drossing flux and then
remove the dross. After this I use sodium crystals to de-gas. Some folks might not like
that, but it was a tip Myfordboy gave me and it seems to help. After that, I find I need
to de-dross one more time and I’m ready to pour
My metal was ready in my electric foundry. I placed the flask on top of the silicone
pad and registered a temperature a little over 100°C. I measured the temperature of
the plaster and this was still a little over 200°C. So I have not maintained the flask
at the same temperature as the metal, which I am aware is the convention.
I took the crucible from my foundry and poured this into the plaster flask. It’s a nice
shade of pink as I wanted it hot, around 700°C. I quickly but safely put the crucible down
and got pumping. Did you see that? Let me show you again…
Watch the metal as I begin to pump… it actually gets drawn down. You can see to metal visibly
shrink. It’s not much, but it’s there. That’s the power of vacuum.
To be honest I never noticed this at the time as my eyes were glued to the gauge. And I
didn’t want to stop pumping until the metal had frozen.
Once it had, which took a couple of minutes, I dunked the content into a bucket of water.
Eventually most of the plaster was washed away and I actually swore… I was genuinely
taken aback. After a little more clean up, this is was
the result. Now if you’re not as amazed as I am, I think
you may be missing the point. These may not be the prettiest coins you’ve ever seen,
but what they are is highly detailed castings that are virtually identical to the wax patterns.
There’s no pockets. There’s no porosity.
Every flaw your eyes are detecting was also evident on the wax patterns.
The vacuum chamber had done it. It had produced a near perfect casting… or at least as perfect
as I think I can achieve. There are some strange straggly bits. Maybe
there was too much vacuum pressure, I don’t know, and on just one of the coins there was
a strange peel-like flaw. It was so thin it could be easily ground away, and its shape
is echoed in the other coin. Maybe there’s a fault with the mould. Or maybe it’s just
because I filled these two so casually, almost without care.
If you’re wondering how all this works… The pump makes use of two one-way check valves
to draw air in one direction only, creating a vacuum in the chamber. As there’s a hole
in the lid, this vacuum is extended into the plaster flask. Casting investment is specially
formulated to be porous. The vacuum sucks on the metal – or perhaps more correctly
the changing air pressure pushes the metal down. But let’s not try any of that science
stuff. Let’s just bask in the glory of these precise castings, easily achieved with a homemade
PVC pump and a homemade vacuum chamber. Now let me tell you something really impressive…
both the pump and the chamber were built for less than one of those perforated flasks would
have cost me. And I could have bought 6 or 7 of those same flasks with the money that
I spent on my vacuum pump. So here is a truly cheap, easy build solution
to your lost wax casting troubles. I honestly cannot tell you how delighted I am with it.
Sometimes simple really is brilliant. For details of the homemade chamber and pump,
look to the vacuum chamber video. It’s very easy to do.
It looks like lost wax casting just got a whole lot easier for me. One thing’s for
sure, you can be certain there’ll never be anything small and detailed in the casting
challenge again, because if there is, I’ll be kicking backside!
Talking of which – that’s the casting challenge and not backsides – we have a
third challenger now. BigstackD is planning to join our next casting challenge in early
September. Both Perry and myself are looking forward to Bigstack’s unique take on things
and no doubt the challenge is going to get even better. I can tell you what we’re casting
next time. It’s absolutely brilliant. We’ll all be having a go at casting…
…though the strawberries and kangaroo meat will be optional.
And I think we can call that a finished video. I hope you enjoyed this one guys, and if you
did, please like it. If you haven’t subscribed yet, then please do. Look out for my other
videos on my YouTube Channel and check out my website.
So that’s it for now guys. Take care and thanks for watching.

100 thoughts on “EASY build Vacuum Casting machine system for Lost Wax / PLA Casting – DIY chamber & Pump : lwc #6

  1. Thank you for that explanation at 11:45.
    At first I was like "wait, how did the vacuum bellow even interacted with the metal"
    Also, in a previous video when you covered a wheel with a thin layer of plaster and then put it in green sand, which had mixed results. You mentioned that the plaster isn't porous, hence why the cast did not turn out very good. But for the method in this video to work, the plaster has to be porous. Did you use different kind of plasters? Or the plaster is just porous enough to work with this method but not the other?
    Thanks in advance!

  2. WOW!
    I love the method!
    Very unique approach! I haven't seen itdone quite this way before!
    All homemade from the flask to the aluminium molecules!
    And on a budget! 😀
    Thanx very much Geoff!
    And congrats on a well won victory!
    Ground your opponents into casting powder! HAHAHAHAHAHAAAAAAA!

  3. I like this. I started with an old Vinyl Album Turntable set up with some rubber bands-you spun it up, did your Investment and casting then released it and it spun like a Centrifuge. My latest project is an electric motor from either a lawn mower or a kids street gokart but this pump you built looks a bit more reasonable to do. I can use one of those motor to build a homemade grinding wheel instead. 🙂

  4. Have you looked into centrifugal investment casting? Jewelers use that technique for casting intricate jewelry. The g-force from the spinning centrifuge pulls the liquid metal into the mold.

  5. Hello.
    Do you know what kind of plaster i need to find in order to do the same ? Are all the plasters fine and porous like yours ?
    And if not, where did you get yours ?
    Thanks for your awesome vidéo !!!

  6. After watching you, bigstackd, swdweeb and Paul's garage I want to get my casting skills in gear. I have heard of lost wax casting and now I understand it much better. From what I have seen of lost foam casting I am not thrilled about it. Keep up the good work and thanks for sharing your knowledge.

  7. Nice results indeed. For drawing a vacuum during the pour most effectively, without ever putting any expensive pumps in the line of danger, the simplest setup is to have a vacuum 'reservoir'. Just pull a tank empty with your pump, and connect it via a valve to your flask, then open that valve directly after the pour. That only gives you a short burst of vacuum that is quickly reduced; but thats all it takes. Once you draw the metal into the detail, there isnt anything forcing it back out again. Its more important that you get a strong effect going quickly, so it can do its thing before any of the detail solidifies, than the length of the pull. Your chamber would do as such a reservoir; its just that you are better off placing your flask over its vacuum release valve, than on top of it without a valve. Thats all theory though; never made any such detailed casts myself i should add!

  8. Thank you SOOO much!!! I have seen people from Men at Arms Reforged and a couple other videos where they have soo much to say and do, that they mention what they're doing in such an off hand way that it literally explains nothing!!! "'We pour the liquid metal into the mold while sitting on the vacuum chamber then it'll go into quench…"' it raised soo many questions that I've been looking for answers to for almost a year now!!! And poof in one video you hit them all!!! Thank you!!!

  9. Have you tried waving a hair dryer over your wax castings to get rid of the 3d print lines?

    I reckon it would smooth out any micro-imperfections.

  10. I like what you’re doing here, but maybe on your 3D prints you used for your silicone molds you should acetone smooth for a better surface finish.
    Or you could print more complex shapes and burn them out instead of max. Effectively skipping a step.

  11. Nice work on the home made vac unit and the results.
    I cast Sterling Silver jewellery with a Kerr vac unit and if you dont mind here are a few tips.
    Reduce the large wax base (button) in your tree and you will have much less wax to burn out. Look at a commercial rubber flask base to see what I mean, the button is usually part of the rubber flask base so you may wish to improvise something similar to reduce the excess wax.
    Steam de-waxing works well, keeps the wax of your furnace and re-hydrates the flask prior to burn out (more steam for wax elimination). A simple rack over boiling water with flask opening downward for about an hour or 2 is sufficient. This will make for a cleaner burn out.
    When the wax is fully burnt out of the flask, the flask mouth will be nice and white as all the wax residue has vaporized. try not to exceed the investment max temp as the gypsum binders in the investment will begin to break down. This might be what cased the flash on your coins.
    Feel free to message me if you wan some more detailed info.

  12. Where do you get your GRS R34WF casting wax? I am having difficulty finding it. Freeman has something that looks similar, but …

  13. Geof, there is a chance to use normal plaster? (The dollar store one) here in Spain is kind of difficult to obtain investment casting plaster. Many thanks

  14. Can also get a small tank that you vacuum out before with the powered pump then open it to the chamber after tgey pour

  15. I know you posted this a while ago, and I'm unsure if you still use it, but if you do, one thing that I think would benefit you, is add a tank in between your pump and your chamber.

    While your metal is heating, you can draw a vacuum on the tank, pour your cast, and flip a ball valve to pull a vacuum on your chamber from the tank and then keep pumping to maintain. Youd get an instant draw that youd then maintain. Minimal heat loss from the pour.

  16. Thanks for buying and using our stuff and congrats on the awesome result. Especially like the Overwatch badge 😉
    You can get the wax (and some of the other bits) here: https://www.hswalsh.com/product/grs-blue-injection-wax-1kg-r34wf-tc01934

  17. THE POWER OF VACUME ,! you got a sub mate..brilliant,something I've been thinking of trying..and you've convinced me too..TY👍👏🤓

  18. Would be interesting to see how big the deference between vacuumed and not vacuumed is, to the same example piece.
    Nice work thumbs up.

  19. The fins I'm the casting is due to improper water powder ratio. More water in the investment and also improper burnout cycle, too fast heating of the investment , which cracks the investment due to steam generation, which cracks the investment plaster because the player was weekend due to improper water powder ratio.
    My two cents

    May all be happy and at ease, free from dis-ease.

    Happy casting.

  20. those flanges are flashing caused by cracks in your investment. normal with to fast heating at the beginning of burnout. also will be better to have vacuum before you pore.
    electric vacuum pump with a bit of a camber is best.
    well done. those ate good castings.

  21. Cover the whole outside of vacuum chamber with silicone and apply vacuum for 4 minutes then one more layer and let it cure.
    Could probably use latex paint or something that is watertight and flexible when cured.

    Edit: great casting result 😀
    Very impressive details

  22. Your making great progress. Few tweaks like properly weighing plaster mixture, and completely drying and heating it much more slowly will help(chemicaly bound water breaking down can also produce enough expansion to crack mould if you don't go slow enough. Also look into ceramic shell casting materials. For your wax using a better silicon you can preheat the mold to be as hot as the wax.

  23. Don't they make a perforated cylinder for frying hens like that?

    Here is what I am referring to: https://www.tigerchef.com/winco-fc-ss-flatware-cylinder.html

  24. I've been watching Alec Steele for a while and this popped up in the similar videos lists. I'm glad it did, very entertaining and great explanation of the whole process. Thanks so much for sharing. I'm looking forward to watching more.

  25. Your flask temp should be about 550 C for silver casting with metal temp about 950 depending on thickness of items cast correct temp are crucial for good results start pumping before you pour metal. Your flanges on the coins is due to to much water in your slurry it cracked and produced these flanges

  26. Great video, love the outcome. Have you thought of having a pre-pressured vacuum tank (large PVC tube with caps and tapes at both ends) so once you stop pouring the metal you can just open the first valve to start the vacuum and if more is needed open the 2nd and start pumping plus you could pull the vacuum on the tank using your electric vacuum

  27. Instead of manual pump = why can't ypu try to hook it up to a household vacumn cleaners – these are cheap and I found so many on the road side – I wonder if that warks better as you can get a constant and strong vacumn suction

  28. Inspirational stuff Geoff. Good quality video and a calm and informative narration, mixed with a bit of humor makes your content very much worth the time. Thank you.

  29. This is amazing stuff. I totally subbed! 😀 I can't wait to try this! Should pair nicely with my new Anycubic Photon resin printer! 😀

  30. Nice video.  If you used an old fire extinguisher or gas bottle (make sure to flood it to drive out any gas) or even demijohns you could make a "vacuum reservoir" between the pump and the chamber to give an original hit of vacuum before you get pumping.I've heard of old fridge pumps being used to make vacuum pumps and 3" copper pipe and a foot pump being used to make a pressurised wax injector – not that I've made any of these myself.

  31. or just put a much bigger pouring cup on your mould to increase the pressure so the mould fills fully (and maybee increase the temperature of the metal if the mould is'nt filling) and to provide a source of molten metal while the casting freezes eliminating shrinkage faults

  32. So started off watching one video, then one more and so on….good at explaining and goes into enough detail to make sense.
    Sometimes wish i had a job and i could afford cool things

  33. You should try adding a valve between your vacuum box and where the casting is placed. Then you draw a vacuum in the box and then place the casting on top of the vacuum pad and them turn the valve allowing the air in the casting to flow into the vacuum box.

    You could use your round vacuum box for this. I would create a little support stand to hold that silicone pad and run a brass fitting (hose fitting) into the silicone pad and do the same to the plexiglas/acrylic top of the vacuum chamber – then run a line from the silicone pad to the vacuum chamber (the valve would be placed on this line). You don't wan't to fill the chamber with stuff this time, you want it empty. Draw a vacuum as high as possible (you can use your good pump for this b/c it's drawing room temp air) and keep the vacuum running up until you pour.

    Then at pour time, shut off the vacuum, pour the casting & place on the new holder and then open the valve and the vacuum chamber will pull all the air from the casting into the chamber and you don't need to worry about pumping fast.

    You could also do the same with an old propane tank instead of a vacuum chamber. Maybe draw 50% vacuum (the larger the tank, the better) and then crack the valve to pull air from the casting.

    Another way to do this would be to add a little water to a propane tank, heat it with the valve open until it steam exits. Remove from heat & close the valve. Allow to cool. You now have vacuum inside the tank. Connect hose/tube to casting holder & open valve once poured.

  34. DIY WATER GLASS,… AKA … SODIUM SILICATE or POTASSIUM SILICATE…..WORKS w/ Po'Paris too…. impervious to heat… makes firebrick with silica sand and fireclay too… and more…. but yet sooooo much more.

  35. Perhaps use some plastic plumbing pipe as a vacuum accumulator? Or an old welding gas tank that's aged out of pressure service? You could use your nice vacuum pump to pull the accumulators down, then isolate it and use the vacuum you built up for casting.

  36. Hello I have used tin, instead of wax, then i have put tin in oil sand and burn it out, It works perfect, My question can you use vacuum on oil sand or can you centrifugal cast with oil sand? And my second project Use bismuth and tin for much lowwer melting point, Or maybe gallium?? Can you experiment whit this things? I have succesfull burnout tin out of oil sand withoud damaging it!!! But i dont know casting with centrifugal or vacuum with oilsand

  37. Since you have a 3D printer, have you tried doing lost PLA casting? I think that they make filaments specifically for that.

  38. I stole the compressor out of a refrigerator to use as a vacuum pump.

    My castings are great, but my food… not so much.

  39. You can use your heat sensitive vacuum pump if you vacuum an air tank, then attach the tank to the mold install a shutoff valve for a quick vacuum pulling the metal in using only negative pressure from an air tank thus the vacuum pump will be safe and totally away from any and all heat while the hot liquid metal begins to be pulled in the mold much faster and more efficiently. Thanks for all your inspirational videos. Keep them coming!

  40. Have you considered steam casting?
    In a nutshell you prepare and burn out the investment, melt your metal on the top of the sprew, a wet down fireproof pad is pressed on the top of the flask and the steam pushes the metal into the investment. I first saw this back in the 70s so there must be improvements on the technique.

  41. wat you could do is use a old propane bottle , vacuum that with youre expensive pump (no heat at all) before the poor and basicly use it as an accumilator
    first pump the vacuum with the handpump close that off and open the vacuum inside the propane bottle a little to slowly suck out the air leaking intoo the chamber
    you could allso motorize the handpump using yet another wheelchairmotor and a tall crank

  42. You know dude, if you don't want a separate blender in your shop, you could just put the agitator in your drill.

  43. I used to do lost wax casting in silver and over many years made thousands of parts. My advice is – buy a cheap mechanical centrifugal casting machine – the force it produces on the molten metal is much higher than a vacuum machine and produces much better castings.

  44. The flashing on your coins was a result of a fractured mold. This cracking occurred because you added new investment on top of the insufficient initial batch. I won't go into all of the details here, but the bottom line is that you should have poured out the investment before it could cure, and then made a fresh batch.

  45. We had some pretty good luck pouring pewter coins in a split mold carved out of soapstone with a small CNC milling machine. We made the mold, and a friend poured around 100 coins with it as I remember.

  46. Watched this a few times, as my vacuum chamber is woefully unsuited to vacuum casting, and this looks liek a wonderfuly affordable solution. One thing has sprang to mind that I don't think you've changed in recent videos. Where you're using a silicone gasket to provide the seal, then placing the flask onto it, once sufficiently cooled down as to not pose a melty risk. Why not use a fire brick with a hole through it to match on top of the silicone gasket, and place the flasks on to the brick, that way you'd not have to wait ages and reduce the temp of the flask before pouring? Like, you could surround the non touching edges of the brick with more silicone if you're worried about reduction in suction to the hole too? 🙂

  47. recycle a refrigerator pump and source a compressed air tank, draw a vacuum on the tank and then hook the tank up to your chamber and voila, you don't need the pump and most of that stuff is free or cheap

  48. To locate your leak in your vaccum box try pressurising in it then using some soapy water. It might work. if air cant escape then it shouldn't get in. Great video by the way.

  49. Try using a cnc mold. You can machine the wax to a very high degree of detail. Additionally add a valve between your mold and the vacuum chamber. This way you can draw a vacuum into the chamber prior to pouring. When you pour you can open the valve and it will draw in fast and stronger than starting the mechanical or electric vac pump, which needs to draw the air out of the plenum. Essentially your macdonald cups are just reducing your plenum size. The larger the plenum, the longer you can maintain your high vacuum draw on releasing the valve.

  50. Maybe pre-heat the silicone mold to prevent filling lines? Silicone should be good for well over the wax melting point.

  51. Try breaking the vacuum casted metal in half and look at the grain structure. I've heard if you do it in vacuum, there isn't any crystallization, the whole piece becomes a single crystal.

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