Kart floorpan

General Composites Discussions Composites Talk
#21

Looks like you can buy PTM&W Epoxy Resin here at Aircraft Spruce for a very reasonable price:

AEROPOXY From PTM&W Industries
http://www.aircraftspruce.com/catalog/cmpages/aeropoxy.php

It looks like it would be an excellent choice if it is backed by Burt Rutan I would say. He is definitely “the man” when it comes to composites. You will notice that Aeropoxy Epoxy Resin is a 3:1 by volume mixture ratio like I stated most stronger Epoxies are. I would definitely try this resin if I were making a part such as yours.

I would think the “01-42135 Aeropoxy QUART KIT” for $15.65 would be a good quantity to purchase for your project.

#22

Aeropoxy is formulated for the aircraft industry. You can get their other line of resin (not named aeropoxy). I use it for tooling purposes and many advanced composite shops around here use the same product. CarbonJoe also uses PTM&W

~$150/gallon, it’s not cheap though

#23

All of this information is great and I have just one more question, I promise. I really like the idea of Vacuum bagging it. What type of Vacuum am I needing? Could I convert an old AC vacuum pump used to suck down AC systems on cars for this? I am not sure what type of vacuum it pulls but could find out.

Matt

#24

Your A/C vacuum pump can pull a full vacuum or at least very close to it. It might take longer to evacuate all of the air out but it’ll hold a very strong vacuum. Probably stronger than you need. Full vacuum is 30" of mercury. Your pump will probably pull at 29" if not more. You want to regulate it down to 20"-25". Anything higher and you’ll end up with too little resin.

#25

I finally got a chance to layup the floor pan for my kart last night. The final part turnout out very well but I did have some problems and, as always, learned alot. This was by far the largest piece I have ever made at approx. 24"x24". The first problem I had was with the first layer of carbon. I first layed down a coat of epoxy go get a smooth finished surface but when I went to put down that first layer I just could not get it straight and get the right amount to overhang (I had cut all the material 1" bigger all the way around). I bet I layed it out and took it up 5-6 times before I was happy with it.

Here are the layers:
—5.7 oz carbon (finished top/first layer I layed down)
—11 oz carbon
—5.7 oz carbon
—1.8 oz kevlar (finished bottom/last layer I layed down)

Next problem was that I underestimated the amount of epoxy that I needed for the 11oz carbon. It really soaked it up but I mixed up another quick batch and everything turned out fine. The last thing was not really a problem but more of an observation. I found the kevlar very hard to wet out and get all of the air bubbles out. I can really see where vacuum bagging would help.

Overall I’m very happy with the end result but I think the next piece I try will be vacuum bagged.

Does anyone have any advice on laying out the material? I thought if you roll it up on a tube and then roll it out from the tube it will help keep everything straight. Thanks everyone for all the info and advice.