SuspendAslurry

[no704]

I’m using suspendaslurry to create a mold over PLA that will be burnt out. Casting Bismuth, melting point is around 290c.
Question is what temperature to fire the suspendaslurry at? I’ve been doing castings in plaster, this is my first shell mould. I have a program on my kiln that has worked well on the block castings well from the manufacture of that material. Ramps slowly up to 1200c then down to 700 for a few hours. Would this be appropriate with the thiner suspendaslurry? I sent an e mail to the manufacturer this am and haven’t heard back. Should I pre heat the mould/sand before pouring? I have been using a pour tempature of 325c with good luck. This will be my largest pour to date, conical cylinder 1” thick 7” tall. Going to be a heavy crucible!

 

[mike93lx]

Robinson foundry on youtube does a lot with suspendaslurry and lostpla casting. Might be worth watching some of his videos for tips

 

[no704]

Threw, well carefully set, them in the kiln today. Slow ramp to 750c with a couple holds on the way up. Will see tomorrow how they hold up. Watched one guy on YouTube that just uses sand to hold the mold. I think I will fully bury these and preheat for the pour.

 

[no704]

Some cracking, but should be serviceable.

 

[Meleon]

Have you cast them yet? looking forward to seeing the results.

 

[no704]

Will. Cast the first one tomorrow. It is spending the night in a SS pot buried in sand @ 310C. Will be just under 20lbs of Bismuth poured into it.

 

[no704]

Cast this today, using investment plaster.

 

[Meleon]

Nice.
I’ve sand cast PLA printed parts. I’ve never had any luck with wax investments because I’ve never a consistent way to control the burnout. I have a small burnout kiln now so I might give it another shot.

 

[no704]

Got a cheap pottery kiln off of creigs list. Put together a tempature controller on Amazon. Have a few hours and less then $200 into it.

 

[no704]

Came out pretty good, soaking overnight. Hopefully will be able to remove the core! Got in a hurry and started to pour the sand out after around an hour and a half. Started leaking from the spru cup!! Second part in sand in the kiln for the night.

 

[Meleon]

That looks like a perfect casting to me.
It always surprises me how long it takes for castings to cool down. (except of course if the gates decide to do a cold shut)

Is that bronze?

 

[no704]

This one had a pretty good crack in it. Leaked a bit. Next mold for tomorrow also had a crack, went over it with Al tape before sanding.
It’s Bismuth.
Turned out ok thou!

 

[no704]

Pour today was a huge failure, bottom blew out. Might be able to get pics in the am.

Lessons learned.
Small Interior walls don’t coat well
Is subject to cracking when firing.

Next round will have block casting plaster for cores.
Tring some high temp fiberglass mesh in the shell to control cracking.
2 out of three isn’t bad for the first time using a new technique.