I will post here to save a new thread.
I've just searched the forum for relavant posts and read most of them.
This post is long and rambling, thanks in advance if you have time to read and advise!
I need to sort my casting out!
It needs to be better quality, higher volume, and use less materials, as this means I can minimise costs and thus, prices.
At the moment I am using two part molds which gravity fill from a resin channel underneath the parts.
Im then pressure casting at 45psi. This approach gets me probably around 90% good parts without any air bubbles, though my milage varies depending on the mold.
I would like lots of advice on switching my mold making process to vacuum casting. using one/two part molds with just a top channel, as used by forgeworld, scibor, and shown in deadmeat30's admittance form.
Ive found this vacuum pump-
http://www.hvacstore.co.uk/acatalog/VPU ... _pump.htmlwhich I would propose to use with a thick polycarbonate sheet and custom made silcone ring, stuck on top of one of my existing pressure pots. Is this a suitable pump?
Is it possible to JUST apply a vacuum for 30 seconds, to suck all the air out, then remove the tray from the pot, allowing it to cure under atmospheric pressure? obviously for "difficult" molds I could just stick the pot lid on and apply pressure as well.. but Id hope for a lot of my parts vacuum alone would be enough.
Deadmeat, Is this roughly how forgeworld do it? I read you mentioned they dont use pressure.
The plan would be to stick to pressure casting for my existing molds, but for all future components, make two part split molds.
Im still trying to figure out how to make more than one of a split mold.. forgeworld for example must make hundreds of the things..
When you make the split mold, its very hard to cut round the master without damaging it, and if you damage the master you cannot make another split mold from it?
Is it easiest just to make a two part mold but have one part partially enclose the master? that I can is doable using mold plates to duplicate each half.
How do you guys who use split molds a lot solve this problem?
Once Ive got my molds, I just strap them up as normal, pour resin into the top channel and vacuum them, presumably I need quite high walls in the channel to stop the resin splashing everywhere?
Thanks for any advice.
Joel