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Fulmen
International Hazard
Posts: 1693
Registered: 24-9-2005
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You're right, using cold ingredients should be the first step. I already use a bit excess of water to reduce viscosity, not sure how far I can push
things before strength becomes an issue. I'll add calcium hydroxide to the list, although I think I will start with water soluble additives for
simplicity.
Edit: Just look at this handsome fella
[Edited on 31-10-22 by Fulmen]
We're not banging rocks together here. We know how to put a man back together.
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Fulmen
International Hazard
Posts: 1693
Registered: 24-9-2005
Member Is Offline
Mood: Bored
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I'm in a bit of a pickle: My quick and dirty setup is starting to hold me back, but this was always more of a side-gig than the main focus. So do I
call it quits, trod on with sub-par equipment or build a new set of tooling?
I did stumble across this though: https://contenti.com/casting-supplies/casting-flasks-investm...
It's a perforated flask liner that provides channels for the vacuum in plain flasks. Should be simple enough to DIY, and would simplify flask
construction immensely.
We're not banging rocks together here. We know how to put a man back together.
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Rainwater
National Hazard
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Registered: 22-12-2021
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Good equipment is great if you know how to use it. Unfortunately, the best way to learn is to get good with crappie equipment. For casting pewter, i
wouldn't spend alot of money.
The methods you are using are required for much higher melting metals, they should work the same for lower temps. Dont give up, its an art form. Right
now your figuring out what not to do. Soon enough youll hit that sweet spot and get that perfect piece.
Short of completely changing your mold method, take a fired investment, and bust it open.(i know, all that work for nothing) inspect for ash/char and
adjust your burnout procedure accordingly.
Pla is crap to burn out properly. 750~1000c for 8 hours 8n an oxidizing atmosphere. Only professional investment can handle that.
They do make an ashless filament and printing with it is not no bad. But wax is best.
If possible, maybe print a negative 2 piece mold, and fill it with wax. Then cast the wax. At a minimum it will increase your production rate. I use
ABS and preheat the mold in boiling water then pour in hot wax.
It will also allow you to do touchups to the casting before the pour
"You can't do that" - challenge accepted
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Fulmen
International Hazard
Posts: 1693
Registered: 24-9-2005
Member Is Offline
Mood: Bored
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The 2-piece mold isn't really interesting for this work. Too many constraints on shape and I'm really only after one or a few parts for now. But sure,
for larger series it would be an obvious choice.
I'm leaning towards new strait flasks and paper liners. Perhaps a groove or two on the inside to aid retention, that's easy lathe work. The perforated
flasks really need a flange of some sort for the vacuum seal that adds a lot of complexity to the fabrication.
I agree that PLA has it's limitations, so I'm going to order some PVB one of these days. I know the Polycast is purpose-made for the job, but it's
more expensive and my regular dealer doesn't stock it.
As for the retarder experiments I've tried cold water with 0,1% cream of tartar. It works to some extent, but I'm not sure if it's due to the tartar
or the temperature. But it's good enough, with a vibrator I don't need more than a few minutes of work time.
BTW, adding more water is not a good solution for this setup. The vibration causes the investment to segregate, in fact I've had to reduce the water
content a but to prevent that.
We're not banging rocks together here. We know how to put a man back together.
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