Michael just shared a new project: "Hot-Wire Bender for Acrylic"
I am in USA
concerning the hot wire acrylic bender, I tried making one using 20 gauge nichrome wire and a 12VDC 5A power supply but it doesn’t heat up. can you help me figure what I have done wrong, please?
G’day @Bill167505,
20AWG is pretty thick - In my version I used 28AWG. Do you know the rating of the wire? (eg. Ohms/meter)
I would guess that the resistance of your wire is so low that the supply cannot maintain 12V across the length. What voltage do you measure across the wire when it is powered - measuring from copper wire that isn’t hot, of course 
My experience using the bender over the past six months or so is that it could always be hotter… I’ve found that my power spec is about at the minimum usable threshold. It looks like I’m running about 70 Watts over 0.5m.
You’re working with 12V, 5A = 60W which implies perhaps a shorter length might work with this supply. What length are you working with at the moment?
had to go with the wife
probably couple hours before I get back.
will reply when I get home.
thanks
I measured the voltage just now and it is jumping all over the place. most I saw was about 3.4 volt. a lot of the time it was below 1 volt. measured resistance also, for the 20 inches (50.8 cm) I got 1.5 ohms. don’t know if that is useful info, tho.
Bill
Sounds like the resistance of the wire is too low for that power supply. At 12V, the current demand is too high, and the power supply is going into overload protection.
If you must use that wire, you’re going to need a higher-current power supply for the same length, or increase the length of the wire used by doubling it back and forth, increasing its resistance. That could be tricky, because you’d have to make sure the wire never shorts against itself.
so that means I should try 28 gauge?
Hey Bill,
I’m sure @Michael will be able to give a better answer here, but I can at least say using a higher gauge wire (thinner) will work better.
A good explanation on why wire gauge matters is because the thinner a wire is the more resistance there will be to the flow of current and more resistance means more energy loss (check out this page for a bit more of an explanation). The energy loss in this case is in the form of heat from the Nichrome wire.
If the resistance in the wire is really low (lower gauge wire) then you will end up having a current flow too high for the supply like Michael mentioned, which will cause the overcurrent protection to kick in and drop the voltage.
I’m not 100% sure on what the correct gauge will be, but if you can find the Ohms/m rating on each gauge of Nichrome wire then reverse engineer it from there with the values you already know (Power and Length) I’m sure you can find something suitable!
Hope this helps.
I roughly understood how this should work, but I did not really understand where I can use such a device.
Hey Kay,
This project would be perfect for someone that’s working with acrylic and would be excellent when paired with a laser cutter to make precise parts like cases or something like the Pioneers Platforms.
Having another tool under your belt for making is always useful, but will depend on the projects they want to do. There will always be other ways to do it but sometimes the exploration for a project has a greater yield than the finished product.
Liam.
For a long time, I have been wanting an acrylic or plastic bender. I wasn’t able to work out how to find a straight heating element. And then my search was answered by Michael when he demonstrated t
@Brian22570 I’m so happy you built this! It’s wonderful to see the theoretical design for 12V in a successful build. Makes that extra work worthwhile 
Thanks for sharing!
Just saw this today. You probably moved on by now. However I’ll comment just in case your still active. I made a “hot wire” wire cutter for Styrofoam and other soft plastics, works great. All I used was the wire out of an old electric heater. It took a bit of time to get the length of wire correct. But it works a treat off of a 12 volt battery. So tomorrow I am going to make an acrylic bender (apart from thinking of ways to take over the world, that is).
Hi David,
Awesome to see this tutorial is still helping people out!
You should send through a few pictures or videos so we can see your cutter chooch!
-James
@Michael came across this post a few weeks ago as needed a way to bend some acrylic. This thing works great! Watermelon lamp is off to a great start!
Many thanks,
David
Hi David,
Welcome to the forum, and what a welcome. This is a great build so far.
I am looking forward to seeing it complete.
haha unreal @David136180 
I can honestly say I’ve never seen such a lamp before
Hi Michael, thankyou for all the info on the acrylic bender. I needed to bend 700mm of 2mm acrylic but couldn’t get any of my power supplies to get it up to temp so I used 2 x 12volt 7Ah batteries I have in a pack for another project. I twisted 4 x 28AWG (same as what you sell) & powered for 40 seconds to get a nice clean bend. I am going to try using a 6V – 90V 15A PWM DC Motor Speed Regulator Controller from Maker Store & reduce the heat output to give a more even heat troughout the acrylic, as the 15A PWM DC Motor Speed Regulator Controller from Maker Store is only AU$11.55.plus AU$12.00 postage. So for AU$24.00 & 2 x12 volt 7Ah SLI batteries, some scrap melamine shelving. 2 “T” hinges, “U” channel & some cable from Jaycar. Less than a AU$50.build. I did add in the Emergency Stop button I had from another project that I got from China for a few dollars. Cheers Peter south of the border, what do you think
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Hi Peter
Welcome to the Forum!
Very impressive build and a great example of adapting your project around what is available!
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