Bending acrylic

[Ivan Pavletic]

I need to bend acrylic with 180 degrees. After bending it deforms to back side so it is not flat. Here are the pictures.
The acrylic is 3mm and the part that is bending is 3cm. Length is 20cm.
How can I bend smaller parts so that it wont bend the the whole stand to back or front?
It is worse with 2mm acrylic.

[Mike Null]

Please explain your technique.

Are you using a jig of any kind to keep the fold uniform?

[Ivan Pavletic]

After bending I just put weight on it. It worked for bending all things except in this case. I don't use molds. I do have angle bench press which can do all the angles except 180

[Mike Null]

Could you place a small diameter steel rod at the fold?

[Ivan Pavletic]

Something like this?prew1.jpg

[Mike Null]

Yes, that is what I had in mind. Looks like you're ahead of me.

[Rodne Gold]

The way to bend something like that is to use a wire strip bender , its heat is extremely localised at the point of bend ONLY that you will get no "collateral" damage

[Chuck Stone]

I did something similar to your diagram, but one face of the metal 'shim' was rounded.
I made a heater/bender out of wood and lamps from a photo copier. Attached a rheostat
to control the heat and just let it warm, then put the shim down and let the plastic form
around it. Worked ok for what I needed, but not perfect. Next time I did it, I engraved a
line on the back to get rid of some of the material so it bent easier and laid flatter.

[Dave Sheldrake]

Extruded or cast acrylic Ivan?

Extruded has surface tension issues that will cause warping in some cases.

cheers

Dave

[andrew zen]

How are you heating the acrylic? MAPP Gas? resistive wires? Think of acrylic as tempermental, too much heat too fast and it freaks out and turns to wax So it is good to slowly add heat to find the point that it bend without resistance for the first couple of bends, and then optimize. You can build a jig using a hinge and plywood and other things if using resistive wire. Something like a metal brake. When properly heated, acrylic becomes very submissive, so you will have to jig everything to control the bending. Tapp Plastic has a good video on bending acrylic. Seems easy, but easy to make it look like as you have seen. BTW the when you reheat acrylic, it affects its stability in the future if you do drastic heat changes. In other words, you are about to become an expert in acrylic bending.

[Ivan Pavletic]

I have this strip wire, I guess I can control the heat of wire. For bending I use this second part. I did lots of bending with this machine but have not done something thin like this, to bend some 1cm with 20cm length. I use extruded acrylic. Bending line is laser marked line with low power, just enough to leave the mark. And when bending, the line is inside.

pl w1.jpgpl w2.jpg

[Chuck Stone]

you might want to take that bending line and make it a little heavier, so it
removed a bit more material. You don't want to cut through, but take out
enough so there is room for the acrylic to bend. The acrylic seems to be
getting in the way.

Same idea as it being easier to touch your toes if you're not 50 lbs overweight.

[Rodne Gold]

A notch either side of the bend line like this
>----< will also help , but key to it all is the bending temp - you want to get extruded to about 170c ..not the wire itself , but the actual material where it is to be bent..you need to experiment with the wire elements heat
Extruded , lasering and then bending is a bit of a recipe for disaster at a later stage as the bend is extremely heat stressed and can crack at a later stage or if exposed to certain solvents and cleaning agents , have you tried the same thing on cast acrylic..you might get better results.