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12-10-2011, 01:36 PM
| #1 |
| RCC Addict  Join Date: Oct 2008 Location: Finland
Posts: 1,265
|  How-to: DIY Strip heater for bending plastics
I've been experimenting with bending plastics lately and thought I'd share my findings. I needed to find a way to bend polycarbonate sheet in a controlled way that would result in a nice finish also. This simple strip heater makes it easy to bend plastics between 0-3mm. I haven't tried anything thicker yet. The strip heater is simply a 1mm thick steel wire that is heated up by connecting a 2S Lipo to it. I've placed pieces of aluminum L-profile close to the hot wire so that the heat is directed upwards and is concentrated in a narrow strip. This makes it easy to accurately heat up the plastic along the line you want to bend. It takes around one minute to heat up a 2mm piece of lexan so that it is ready to be bent.    Here are some parts that I've used the strip heater for. Two different battery/electronic trays for the XR10:   A servo guard:  And here's a short demo of the bending process (sorry, I'm explaining a few things in Finnish). But you'll get the idea  .DIY Strip Heater - YouTube Last edited by Tomy; 12-10-2011 at 01:43 PM. |
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12-10-2011, 02:05 PM
| #2 |
| Pebble Pounder Join Date: Feb 2011 Location: Grand Rapids, Mi.
Posts: 121
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great job, not to hard to understand what you are doing in the vid  |
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12-10-2011, 05:04 PM
| #3 |
| I wanna be Dave Join Date: Nov 2010 Location: 07456 N. NJ USofA
Posts: 8,314
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Nice DIY job. Lexan is actually decent for cold bending with a sheet metal brake. Plain old polycarbonite will usually crack unless heated. For those that are wondering, the spring is attached to keep tension on the heating element when it heats up. As it heats, it grows in length. If tension is not kept, the wire can contact other bits, not a good thing. We used to do similar for cutting foam cores for RC plane wings. Wood & metal frame ~4' long, .020" Nichrome wire across the frame and a power source. Let the Nichrome heat up and cut away. |
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12-10-2011, 05:28 PM
| #4 |
| Pebble Pounder Join Date: Oct 2011 Location: Exeter Ontario
Posts: 156
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Simple and very effective!!! I was wondering about using another power supply. I have more car battery chargers the Lipo batteries! Last edited by JKMotorsports; 12-10-2011 at 05:41 PM. |
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12-10-2011, 06:46 PM
| #5 |
| Newbie Join Date: Mar 2009 Location: victoria
Posts: 38
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awsome never thought of doing something like this before
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12-10-2011, 07:10 PM
| #6 |
| no talent hack Join Date: Feb 2007 Location: Redwood City
Posts: 2,479
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Do you just have the positive going to one side and the negative going to the other?
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12-10-2011, 08:00 PM
| #7 | |
| RCC Addict Join Date: Oct 2008 Location: Finland
Posts: 1,265
| Quote:
Yes, I do. | |
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12-10-2011, 08:10 PM
| #8 | |
| RCC Addict Join Date: Oct 2008 Location: Finland
Posts: 1,265
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12-10-2011, 09:16 PM
| #9 | ||
| I wanna be Dave  Join Date: Jan 2004 Location: Detroit
Posts: 3,583
| Quote:
The clear plastic that cold bends, is PETG, which is not a Polycarb, but similar in properties often makes people confuse them. Quote:
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12-10-2011, 09:41 PM
| #10 | |
| I wanna be Dave Join Date: Nov 2010 Location: 07456 N. NJ USofA
Posts: 8,314
| Quote:
 You just have to remember to set the backset on the clamp bar to allow for the material thickness (compared to sheet metal). | |
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12-11-2011, 12:49 PM
| #11 |
| Quarry Creeper Join Date: Oct 2011 Location: Detroit
Posts: 347
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That is a very useful idea and a very cool tool! What kind of wire did you use for the element? Would you recommend that or is there something better to use? Also, does a Lipo have to be used? Could this damage it? Could any other battery type be used (ie: NiCd, or NiMH)? Thanks for posting the video! Last edited by DiggyStyle; 12-11-2011 at 12:51 PM. |
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12-11-2011, 01:05 PM
| #12 |
| Pebble Pounder Join Date: Sep 2009 Location: Abbotsford, B.C., Canada
Posts: 186
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Nice job. I've used stainless safety wire with decent results. Alot of the airplane guys have used a model train power supply with good results. You can vary the input to control your heat.
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12-11-2011, 03:07 PM
| #13 | |
| RCC Addict Join Date: Oct 2008 Location: Finland
Posts: 1,265
| Quote:
 The wire I'm using is just cheap 1mm thick steel wire you can find at a hardware store. The right choice would be Nichrome wire. It probably has a higher resistance than the steel wire I'm using and should therefore have a lower amp draw. I used a very old and tired Nimh-pack for my first test as I wasn't sure if the plain steel wire would work. The Nimh got a little warm and wouldn't last too long. The 2S 4000mAh 20C lipo doesn't get warm at all and should last for at least 20 minutes of continuous use. I'll try to get my hands on some proper Nichrome wire and report how that works. One guy on a Finnish forum told he's using 0,8mm Nichrome wire for his foam hot wire cutter wich draws approximately 3,5A. I've got a 6/12V 8A 1:1 car battery charger I was hoping I could use. But with the way the heater is setup now, it looks as if the amp draw is still too high for the car battery charger. I'm hoping the use of Nichrome wire will drop the amp draw down to a level the car battery charger can handle. | |
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12-11-2011, 07:21 PM
| #14 | |
| I wanna be Dave Join Date: Nov 2010 Location: 07456 N. NJ USofA
Posts: 8,314
| Quote:
As to a power supply, pretty much any DC source will work. A variable voltage supply it best so you can vary the heat. It also means the wire element will last longer (basically you are making an incandescent light bulb, they only last in a vacuum.....). The DC supply just needs to provide enough amps. You are likely looking at a 10A minimum, 20A+ (adjustable voltage is better) is preferred. You could always hook it up to a small car battery with a charger also hooked up to the battery.  | |
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12-11-2011, 07:49 PM
| #15 | ||
| R.I.P. Chip   Join Date: Jan 2004 Location: The Crawler State
Posts: 13,938
| Quote:
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12-11-2011, 08:21 PM
| #16 |
| Pebble Pounder Join Date: Oct 2011 Location: Exeter Ontario
Posts: 156
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I have various heater wires in all kinds of guages and even flat as I work in the textile area and have fabric cutting machines and plastic film welders. I'm going to give some a try tomorrow and see what results. |
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12-11-2011, 08:46 PM
| #17 | |
| RCC Addict Join Date: Oct 2008 Location: Finland
Posts: 1,265
| Quote:
I did some research and found that the steel wire I'm using should only have 1/7 of the resistance of Nichrome wire. Less resistance means you are closer to short the system and the amp draw will be higher. The use of Nichrome wire should improve things a lot. Last edited by Tomy; 12-11-2011 at 08:55 PM. | |
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12-11-2011, 09:28 PM
| #18 | |
| I wanna be Dave Join Date: Nov 2010 Location: 07456 N. NJ USofA
Posts: 8,314
| Quote:
  As Tomy & I stated, Nichrome is the best bet. | |
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12-11-2011, 10:40 PM
| #19 |
| RCC Addict Join Date: Oct 2009 Location: San Francisco
Posts: 1,927
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Nice setup you got there! Simple but effective. Im personally not balzy enough to use a lipo when I power my hot-wire setups but hey your gamble  . Most hot-wire setups use a light bulb to help bleed off excess power safely when they are being used in conjunction with a power supply. Not a bad idea with a battery either.
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12-11-2011, 11:53 PM
| #20 | |
| RCC Addict Join Date: Oct 2008 Location: Finland
Posts: 1,265
| Quote:
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