This is filed in the ‘Huh, I didn’t think that was going to work’ category.
I wanted to try my hand in thermoforming. The idea was to cut out a pattern or a raster and ‘soften’ the acrylic around a form to create a bracelet for my wife with the following items.
A Powder coat oven.
A Bowl.
A (Empty) Beer bottle.
A Glowforge.
As always this adventure starts out in Fusion 360 and a Woodchuck (Beer). I made a couple repeating patterns then cut them out. Since the end result was basically was going to be jewlery- I figure I’d make use of the scraps by making them into earrings.
Then I went out to the garage a fired up the oven and set the controller to 450F. Went back in the house and pressed the button to start the cuts. At this point I had an empty beer bottle. I washed it out and cleaned it out with cold water then dropped it into the freezer. And 18 mins later I had these.
Grabbed the Woodchuck then trek back out into the garage. I grabbed an old clay bowl and placed the flat stock across the bowl then inserted it into the oven.
(*Note. The example above is from the second attempt- I seriously didn’t think it was going to work.)
Waited 3 mins then switched to ‘broil’ then watched it sag into the bowl. Once it touched the bottom I waited 20~30 seconds- pulled out the pieces out and tightly wrapped it around the frozen beer bottle. Did the same for the second piece.
I don’t think you need to have a frozen bottle (in fact I’m surprised it didn’t crack on you). When I slump acrylic lace bowls (cut lace patterns into an acrylic sheet and then heat it to shape it around or in an existing bowl of the desired size) I use either a room temp bowl or I heat the bowl in the gas grill with the acrylic. It assumes the shape pretty easily and cools pretty fast after being pulled from the gas grill.
I like the gas grill vs the coating oven because I can flip the lid up and get in there to manipulate the acrylic while it’s warm and everything stays pretty warm vs pulling it out into the cold. Just a habit I have from doing beadwork and moving beads between the torch and the annealing kiln. I try not to heat cycle too many times because it can make me rush or it can weaken the material.
Great idea and execution! I’ve been enjoying all of your creativity!
I’ve been doing this for a specific research application. In my application, I found that if you preheat the oven to 150 C (300 F) with the mandrel inside (aluminum in my case), the part doesn’t cool down so rapidly as you roll it and you can get a perfectly cylindrical form. I typically only have 1/32" acrylic in the oven for a minute or two before rolling. I put it on a clean surface so as not to transfer surface imperfections to the part. I’ll post more details and pictures once the study gets published
Torches work but they’re hard to control - too close and you’re melting or even burning it. Good for small things.
Heat guns are good for this size piece or simple short bends.
The oven (or gas grill) is good for large pieces. Watch out using the kitchen oven - there is a (small) chance it will catch on fire. Better to use a shop oven or outdoor grill where the fumes won’t collect.
For future reference, acrylic fumes dissipate from the kitchen oven faster than epoxy/carbon fiber fumes after post-curing. Jus’ sayin’.
And I use a heat gun to bend 1/4" thick acrylic into tight 90 degree corners, a heat gun would have no problems with something like this as long as you keep the heat even.
A toaster oven would probably even work for a small piece like this.
I use a heat gun for straight bends where I can direct the heat evenly. Like the tissue box holder I made to slip over the pocket in the backseat of my car. A line bender would work for those too.
For larger projects like slumping bowls, the oven or gas grill are a better solution. Fast widespread heat without the problem of sections cooking off while others are heated.
what a great an innovative idea! You are proving the concept that with the right technology - artisan work can be made available to the masses. Can’t wait to get mine.
