www.TK560.com

[anakinjay]

Ok guys, few quick questions...

A buddy of mine has a vac pump he's willing to give me if it'll work. He plugged up the hole and ran it to see what kind of vacuum it'll make.

This is where I get confused.

I thought "/hg was measured backwards starting at 30? so 21 would be more "vacuum" than 28?

well his pump started out at zero and slowly rose up to 21 and stayed there.

Anyone know if this pump will work. All I know is the guard starts at zero and goes up to 21, and it's 5 cfm.

I'm working on a 24" x 24" table.

Also, I saw those cheap $10 harbor freight pumps that say 28"/hg... if it's measured from 0-30 then wouldn't 28 be awesome? if it's measured from 30-0 then wtf is my friends pump doing? hehehe...

Thanks for the help, I'm pretty confused atm.

[Plasticman]

Low vacuum is 0, 30 is incredible.

If you are pulling 21" with that little pump, that is good. You may have to wait a little bit to pull a tank down with only 5 cfm, but it will be alot better than a vacuum or The Harbor freight pump.

The next thing you will need to look at is tank size.

[drcrash]

When measuring vacuum, the more inches of mercury, the stronger the vacuum.

At sea level, under standard conditions of temperature and barometric pressure, 0 inches of mercury is just the ambient air pressure---i.e., no vacuum---and a perfect vacuum is 29.9 inches of mercury.

So 21 inches of mercury is more than 2/3 as good as the best possible vacuum. It's also over 10 PSI, of a possible 14.5 or something like that, which is pulling about 5x harder than you can expect a good vacuum cleaner to do.

If you use a simple one-stage one-tank system, you'll want a tank several times bigger than the amount of air you have to pull out from under the plastic. The usual thing for a 2-foot-square platen is a 25-30 gallon tank, most commonly a salvaged (usually free for the taking) 30-gallon water heater tank.

Even with a smaller tank, you'll get substantially better results than if you just used a vacuum cleaner.
_________________
Paul (a.k.a. Dr. Crash)

Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com

[anakinjay]

Awesome!

as far as the tank goes, my buddy (same guy) is an awesome welder and when I show'd him the tank someone built themselves here he said that'd be easy. We already have the metal bent and partially welded to form a tank (we're using 1/4 inch thick steel)

it's 24x24x12 so if my math servers me correctly that's
6 912 cubic inches which is about = 29.92 gallons

Sounds like I got lucky

So you guys think 21 in/hg vacuum with a 30'sh gallon tank on a 2'x2' platen is enough to pull down plastic for a stormtrooper costume?