Forming ABS plastic

First off, what about Mom's kitchen tools?
I get asked about his quite a bit- everybody has a kitchen stove, and some have wondered: Can this thing help me make parts?

The answer: NO. Kitchen stoves are designed for the heating and cooking of things that are safe to consume and SMELL, i.e., Steak Tri-tips, chocolate cakes, etc. that being said, I've used my trusty Amana for worse...

Heating PLASTIC in your home immediately sets up DANGEROUS conditions. MOST plastics "out-gas" when heated, releasing volatile fumes, corrosive agents, not the building blocks of life. Sometimes, the mixtures can be deadly! A lot of plastics (thermosets) just won't melt or get soft, they'll char and go to flames first.

Like most Thermoplastics, once MELTED, ABS will puddle and bubble, and then spectacularly burst into sticky flames. Yes, Mom would be mad.
So DON'T DO THIS yourself. Consider this information on how I play with fire, nothing more.
Most of what you need to know about ABS:
http://en.wikipedia.org/wiki/Abs_plastic
Buried in this info (actually in a link) is the "heat deflection temp" for ABS plastic. It's 185 degrees Fahrenheit. that means, at a uniform temp of 185, it can be deflected. Fancy way of saying "bent".

But you don't really want to fully heat a sheet, just bend it to your will.


This is an electric bending strip. Made of a teflon/fiberglass mesh, with a heating element woven into it.
http://www.interstateplastics.com has these in different lengths, this is a 24".


Making STRAIGHT bends is much easier if there is a groove routed into the backside of the bend. It just takes a bit longer to heat through without, and a bit more care is required to get the bend positioned correctly, and be straight.

Depending thickness, time will vary for getting the plastic to the right temp. Note the digital timer. By putting it in count-up mode for the first bend, I determined that 2.5 minutes were needed for full heating. Then I just set up a count-down for the next parts, and was able to carry the timer while I did other small tasks.
ABOVE ALL, you don't want to become distracted and forget about plastic in-process.



The finished bend.



No, these weren't airsoft parts...

Next: "Hey Honey, here's a Macy's $50 gift certificate I forgot to give you last Christmas!"


"Watch your language", that was easy, I won't see HER for four or five hours.
Upside, the house will air-out if needed. Downside: A gift certificate only opens a door, figure it being 25% of the shopping trip's bounty.

So she's off, the mutts are locked outside, and the stove in the kitchen just got done making me some frozen meatpies from Costco. Rather than shut it off, I turned down the temp to 320.

I know, only 185 does the job, but it would take much longer to soften the part. The trick is to get the ambient temp around it a bit higher, so it all softens uniformly.

My example is a drum, or Trommel, magazine for my treasured Marui Thommy:

The drums were made in 50- and 100-round versions. Both were more deadly to the shooter than the shootee, they jammed like crazy.

Rather than fight a strip of 3mm ABS into a band, I'll give it a shot of BTU's, and wrap it around something round, like this stack of MDF disks:


The strip, 20" x 1.70" was laid lengthwise in the oven on lower rack, and the oven light snapped on.
I only wanted the material SOFT, not MELTED! The first experimental parts looked more like egg noodles than drum bands.

So I watched as the strip "relaxed" and then flipped it over, and closed the door for a few more seconds.

Then, it was quickly snatched out and slapped around the form. Grabbing from the oven was done with bare hands, as the contact time was low, and heat doesn't "transfer" from ABS quickly, but holding it against the form (after a slight stretch to make sure it laid flat) required some oven mitts.
By the fourth try, I had it down to a process.


Finished bands, after cooling. even though I needed bands of varying diameters, I only used the one form, as ABS is pliable enough to be final-shaped in or out at gluing.



QUESTIONS?

what is the usuall diameter of the ABS for airsoft materials?

Huh?

I must know where you got the M1928 Conversion Kit. Been trying to do this for YEARS. OR if you made it....we still need to talk.

killbucket wrote:

Huh?

what diameter....... THICKNESS got it finally, been working on too many aircraft models mixes me up(mainly the propeller diameters!)

I use .118/3mm and .235/6mm black ABS sheet.

My TM Thompson is stock except for the magazine and surface coating.

thnx!, and with abs, what temp do you need to bend it?

I set the oven at 350F.

BE CAREFUL-DO NOT TRY THIS YOURSELF-

I found that MORE is not BETTER, here. Letting a plastic strip get too soft makes for a wavy part. you still want to have some stability in the material left when you go to form it.

So I stayed RIGHT THERE AT THE OVEN, watching. I could actually see the phase change start to happen, as the material "relaxed" a bit. Then, I quickly flipped it over, to evenly heat both sides. A few seconds later, out of the oven and around the form.

If I'd had a helper, I would've used a strip of cardboard to wrap around the softened plastic, making the drum sides absolutely flat. As it was, a light sanding smoothed them right out, and left a nice "sheet metal grain" finish.