Will pressure casting cause molds to fill completely with resin?

[wunwinglow]

For pressure pots, I use a couple of paint pressure pots with the internal paint kettle and delivery pipe removed and the hole plugged. I added a vacuum tap and quick release coupling. The compressor isa small one I picked up at Machine Mart.

 

http://www.spraydirect.co.uk/acatalog/apollo_10_litre_pressure_pot_no_agitator.html

 

and

 

http://www.machinemart.co.uk/shop/product/details/pioneer-220-air-compressor

 

I got my air line fittings from Machine Mart too.

 

I'm sure you can find equivilents in your local machine tool suppliers.

 

I run the pots to 60 psi.

 

My vacuum chamber and pump I both bought on eBay. The pump is an Edwards device, and I spent as much as I paid for it again on getting it reconditioned, but t has been bulletproof ever since. Just keep it topped up with decent vacuum oil!

 

Tim

[ChuckT]

That's what I have for my set up already. I just need to get another pressure safety valve for my pressure pot. After trying to do a few Pressure tests to 40 psi (my intended casting pressure) it kept going off at roughly 30 psi! I need it to go off between 50 and 70 psi.

 

It does look adjustable, but I don't have a split straight edged tool to tighten the nut that presses down on the spring.

 

Any ideas?

[ChuckT]

Here you go;

 

 

[ChuckT]

Oops! Kind of big pics! Sorry everyone. I'm still leanring here.

[STM]

Vacuum degassing is by far the best way to go when making silicone rubber molds. I set the vacuum chamber at -30" Hg and close off the valve and let the mold cure in a vacuum for at least 5 hours. When it comes to casting resin, vacuum will indeed work but the resin will usually foam and possibly overflow the mold. You may also not be able to cast very small parts with very fine details with vacuum.

 

Unfortunately, pressure casting will not force the resin into very fine details. I am much happier with the qualities of my castings since I went to pressure casting the resin.  The best way to ensure it goes into all the nooks and crannies, attach a piece of styrene rod, at least 0.060 in diameter in several places on the master to allow for overflow

I use disposable 3ml pipettes to get the resin into the molds. 100 of them costs about $7 online. It is easier to fill intricate molds by injecting the resin under a little pressure rather than just allowing gravity to do it. It is also less messy than pouring.

Edited October 6, 2022 by STM