Vacuum Pumps

[Lownslow]

what to look for im looking into investing in one soon.

[Greg Wann]

http://smcbofphx.pro...ead=1184&page=1

I bought a small single stage one from Harbor Freight. Be sure to get the warranty. It worked just fine on my new vacuum/pressure chamber. Here is a link to a vacuum chamber I just built.

Edited September 28, 2011 by Greg Wann

[Ben]

Check your local pawn shops for used automobile AC vacuum recovery pumps. This is what I use and it works great! My pressure pot doubles as a vacuum chamber. It's pretty simple, I had a piece of 1/2" thick, clear Plexiglas cut into a circle just a bit bigger in dia. than my pressure pot. I then drilled and tapped it so that I could install a "T" with a vacuum guage and a shut off valve. The gasket that seals the lid to the chamber is 3/8" fuel line, slit down one side along it's length. When I need a vacuum chamber, I just place the fuel line around the top edge of the pot and place a small dab of clay where the ends meet. I then place the Plexiglas lid on the pot, turn on the vacuum pump and push down lightly on the Plexiglas. The vacuum takes over right away.

Just an FYI, the vacuum is for the removing the air bubbles from the silicone mold material before the silicone has cured. This will eliminate "positive" air bubbles in the silicone which will leave little balls of resin on your completed part.

The pressurization is for the uncured resin only to force out any trapped air before curing begins.

NEVER vacuum resin!!!!! Trust me, it makes a hideous mess!

Something else that can be done to remove air from your uncured silicone is to place it in the freezer. This will greatly slow the curing process and allow the air bubbles to float to the surface.

Something to remember also, is that when you vacuum silicone, it's going to rise to twice it's volume as the air escapes so make sure your mold box has sides that are high enough to contain it or it will overflow and your part will be half exposed.

Always happy to help with tips!

[RyanSilva]

Get the harbor freight version, with the 20% off and the extended warranty its a good buy!

The only time I will vacuum resin is when I need to suck out the moisture to save it when it starts getting foamy.