ABS Forming

[Preston_Hall]

Anybody doing their own ABS vacuum forming? Cowlings in particular. What type of equipment? Where to get? Got any pics?

Thanks

 

[Climate Models]

We do our own plastic parts for our kits.

It was always done one at a time, but now we are in to large production and need to make several parts in one shot.

Our new system is just being built. It is state of the art with a bottom feed (sucks the material up, not down)

A vaccum former is prety easy to make. All you need is a box with a vacuum source, (shop vac works great) and a frame for your parts. A household oven works great for heat.

Make sure your wife is out of town for the weekend if you are using ABS. It stinks!

Doug Forrester is an expert at "one off" forming. I bet he would be happy to give you all the info you need to set up a small system.

Peter R.

www.climatemodels.com

 

[Jr Branham]

Peter,

Without giving away any trade secrets, what is the advantage of sucking the plastic up instead of down?

Jr. B

 

[Grimracer]

Preston..

I know alittle.. you can PM me if you want.

Grimracer

 

[Climate Models]

No trade secrets here.

When the plastic gets warm in the molding frame, it bows down because of gravity.

If you place this on top of a plug it gets cold where it touches the plug. The top cools quickly and when you go to draw the part down, it makes the sides thinner than they need to be.

When you do it from the bottom, the entire piece of plastic gets sucked up on to the plug evenly and gives you a better, more consistent part.

I hope that makes sense?

Peter R.

www.climatemodels.com

 

[Grimracer]

Preston

They also make versions that inflate the once fallen plastic to avoid the same situation. The nice thing a about this type of system is that no fancy fixturing is necessary for the tool. This same air system is used to kick the part off the tool..

There are a lot of tricks to making quality parts, not just parts.

Do I know what hey all are…no….Hehehe

grim

 

[jasonspeedy]

I've heard that you can make a mold or plug from wood, lay some ABS over it, and bake it in the oven, AND get satisfactory one-off stuff. Is that true? Sounds good for cowlings. I had to salvage a shipwrecked SGX cowl and butcher it for my last cowling.

 

[wswatzell]

For very gentle contours, that might work ok, but not great., but with stepper sidewalls, like less that about 20deg. you will have problems getting the definition. Also, without using vacuum, any sharp inside corners won't exist, because of the nature of the material, & the trapped air underneath. If you are looking for good part definition, you have to use vacuum. I design vacuum forming tools for a living. There are allot of little tricks to get a high quality part, but it is possible to get decent quality parts using a homemade vacuum box, & shop-vac. I have seen plans to make them somewhere before..... Oh, in an old issue of Model Airplane News, I just don't remember which month, & year. I'm sure you can find the plan on the web.

 

[Paul Pachmayer]

Hello Guys,

Try this link, pretty good how to info.

http://www.studiocreations.com/howto/index.html

Paul.

 

[Preston_Hall]

Great site and info! I'm ready.

 

[MikeP]

I have seen 2 different plans for vacume forming tables using a shop vac. One uses the single hole in the center, the other uses peg board material. Seems like the peg board would work better with all the holes to suck through.

http://www.warmplastic.com/

Anybody know which works best?

Mike

 

[Grimracer]

Mike

I have used both and i like ones with the many holes.

Grim

 

[Preston_Hall]

What about suppliers for ABS sheets? And is styrene just another name for ABS. I know the "S" stands for styrene.

Thanks for all the input.

 

[wswatzell]

Styrene & ABS are very different. ABS is prety tuff stuff, it won't break as easily, & is more flexable. Styrene is more brital, & doesn't flex as much. You can get styrene in clear sheets easier that clear ABS. not sure about price differences.

 

[Jr Branham]

Peter/Grim

How about a little info on trimming vac-formed parts. Other than scoring with a knife. I read about using a inverted drill press with a slitting saw blade. How do they get the clean crisp cuts with straight lines. Seems like the plastic would want to shred and "build up" due to heat with a saw. Can a router be used??

Jr. B

 

[wswatzell]

If you make your parts with ABS, & also depending on how thick a material you use. You could use a utility razor knife to cut all the way through, or use a pair of heavy duty scissors.

 

[forming]

The oven approach will get you in trouble with the wife. IF! If, she catches you. You can't do very large parts in the oven either. My wife bought the biggest oven she could find and I still could only pull about 20" of plastic. You take your eyes off it and let the plastic get stuck in her oven and your homeless.

The shop vac will not pull .060 ABS tight. .040 is about it. MY 6hp Rigid vac pulls about 4 inches of Mercury. My vac machine pulls 26".

Styrene is a LOT easier to pull but it's not as pretty as the ABS. ABS makes a better product. The ABS needs to be kept dry or be dried prior to forming. That can be a real pain. Especially in the home oven. I used to leave the ABS in the oven at 180 deg for a half hour. Super stinky. If your looking for clear and don't need to glue it together try Vivac.

I could see an advantage to heating from below and pulling the plastic up but if you oveheat your plastic look out. Talk about smoke. I actually built an evacuation system just in case.