Electronics > Beginners

12-19V strip heater for bending plastics

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slowpoke:
I need an acrylic sheet bender. Checked out prices of the machinery and noped out real quick.
Heatgun bending is not an option as pretty precise and neat bends are required.

Can someone help me figure out how to go about making one ? I've seen some videos of people making them but usually all electrical bits explanation is missing.

Ideally i need something that can strip heat a length of about 600mm, powered by 12V (ATX power supply?) or 19V (laptop power brick, beefier one, over 3 amps? ).

How to go about calculating the nichrome wire i need, gauge and power requirements to achieve needed temps. Don't need the wire to glow white, just to keep to ~200-250 C. (I have some dead toaster heating element wire unwound somewhere in the parts bin...)

Don't want to go full mains voltage (240V) for safety considerations.

Anyone here constructed such a contraption ? Need input :D

beanflying:
I looked at making one ages ago and decided to go pay someone at the time to do it for me  ;)

There is plenty of videos on youtube including the one below but the key to it is control over the sheet when you have the bend area softened so some light clamping helps keep it nice. Also as per the video below the heat is controlled to a localized area by the channel which is fairly standard with the commercial units. Some Kapton or fiberglass tape to keep any bit of the acrylic away from the aluminium might be good too.

Ball park 0.8-0.9mm Nichrome or Stainless Mig wire will be fine somewhere between 12 and 20V. A 12V car battery way back when used to be my go to for Foam cutting at 900-100omm typical temps are similar to what Acrylic needs to soften but the shorter run you will be close at 12V and 600mm with an extra 300-400mm run and an alligator clip to adjust the temperature. You should also be under 5A so even a decent bench supply will cope.

wizard69:
I haven't created a bender but at work we have a variety of heat seal tasks.   What your want covering the metal is PTFE tape.   The Tape is specially designed for such usage.

beanflying:
Unlike the heatsealers the wire is below the surface of the table so you are better off without a cover for faster heat transfer to the acrylic. The bits that could do with some cover are the tops of the aluminium channel or just rebate them slightly below the surface like this should work. Hinges outside the 600mm for the OP and some sort of light clamp on the fixed surface to keep the sheet in place so the bend goes in the correct spot.

Quick and dirty model here https://a360.co/3fAZhCr

slowpoke:
Mechanical part doesn't really bother me, i'm a maker :D Its the electrical part that i'm interested in.
My question arises from the need to make a strip heater on zero budget. I do have some unknown wire from heating elements of toasters and hair blowers, i also want to power it from something less than mains, for safety concerns.

I will dig out the heating wire today, just need to figure out how to measure/calculate/power it at length i need with atx(12v) or laptop(19v) power supplies.

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