The Shop > Composites & Plastics

Vacuum pump

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Brass_Machine:
Hey Rog,

I have done some composite work before, both CF and glassfiber. I have made molds etc.. But I have never done vacuum bagging though. I own a bunch of books and videos  on the subject. I just haven't attempted it yet.

Thats a great link, thanks!

SPiN Racing:
Hi all,

I work at a race shop that makes small Formula 500 cars. A Class of small foruma cars powered by a small Roatax snowmobile engine, with a CVT from a snowmobile. I could go on and on about the performance but thats not the point. :)

We make a variety of composite parts, as well as very light bodywork. A lot of parts we make are "bagged"

The owner of the shop has made a very very nice.. and simple design that was incredibly cheap.

CHEAP being the prime word to hear there.

He used a vacuum pump from a old Freezer AC system. (Used appliance place anyone?)
Then he used 6 old FREON metal containers.. that look a little smaller than a standard Propane tank.
Each of these is connected together with a simple wooden frame.. and the outlets are connected with some PVC plumbing from the sprinkler department.
He has a ball valve that leads to the tanks.
THe ball valve leads to a manifold he made with a DOZEN ball valves leading to small 1/4" clearish plastic water lines.. like those used in refrigerator water feeds.
ONE valve leads to the vacuum pump.

He simply closes everything BUT the vacuum pump valve.. and the tanks.
Runs the vacuum pump while he sets up the run of parts he is gonna make.

The parts are laid out in thier spots on a big sheet of glass he got cheap at a window place. (It was cut huge.. but incorrectly)
He lays out the cotton like bleeder cloth, and then lays a VERY small 1/8 or smaller snake of clay around the outline of the part he is laying up.
Once the vacuum pump is done, he mixes up the resin.

We LIGHTLY goo the parts.. in this case they are all flat parts for chassis reinforcement.. but they could be on a mold.. simply put the clay around the preimeter.
Lay the lightly resined parts up.. be they carbon, kevlar, or simple glass.
Lay a bleeder cloth over the part (cut slightly oversize to the shape)
Lay the peel ply (Clear plastic) over the part, and tuck a hose end fromt eh vacuum manifold under it with a snall snake of clay around the hose.
Finger along the clay lightly.. and move to the next part.

After 20 or 30 minutes they are all layed out.

Flip of each of the ball valves that are hooked up, and then SLURPPPP.. he throws the main valve.

Instantly the whole thing sucks down real good.. and the bleeder cloth picks up the spare resin from the parts.
He then throws on the vacuum pump again and lets it slowly chug for the next half hour or so while the resin kicks off.

PTsideshow:
In the latest HF flyer they have two new real style vacuum pumps for fridge systems. a 1.2cfm $69.99 98074http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=98074
And a 2.5CFM $89.99 98076 http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=98076
Could be a low cost pump for the occasional user.
 :thumbup:

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