DIY Hot Wire Foam Cutting Table (not working)

Thread Starter

Smapa

Joined Oct 2, 2020
6
Hi I am trying to build a hotwire foam cutting table and my wiring and parts are functioning but not the way they should as the nichrome wire is not heating enough and my dimmer stops at 60 (before it stars flickering) rather than 100, my knowledge for this sort of stuff is whatever comes before beginner. My guess is I either used the wrong wire or I used the wrong type of metal at some point or my power supply is wrong, I have no idea.

There are 2 videos that I tried to go off of and theirs works. I am sure I am close. the Nichrome wire gets warm but not very hot like it should, and no other metal feels warm.

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Nichrome wire (for cutting) HWCW -2, 27 gauge

http://www.jonhudon.com/hotwire/1.jpg
http://www.jonhudon.com/hotwire/2.jpg (etc)
(replace number in address above for more images 10 total)

Videos I used as reference to build:


Thank you for your time.
 

sagor

Joined Mar 10, 2019
479
I would suspect your 12V at 200mA power supply is not enough. Either the current is too low, or the voltage drops across the steel support etc. is causing too high a resistance (causing less current to flow).
If the controller is properly controlling current, try a power supply rated around 1A instead of 200mA. That supply you are using will drop voltage quickly once it exceeds 200mA
 

MaxHeadRoom

Joined Jul 18, 2013
23,639
It may be because your secondary voltage is not high enough.
Is the plug feeding the mains transformer direct, with a dimmer on the primary?
A wall wart won't cut it, even a larger one.
Max.
 

Thread Starter

Smapa

Joined Oct 2, 2020
6
Can I cut an extension cable and attach that directly to the box where all the wires are going? or will that blow it up? Sorry I am very ignorant to this topic (electronics in general) though I am finding it interesting.
 

Thread Starter

Smapa

Joined Oct 2, 2020
6
If you mean a 120V or 240V supply cable, DO NOT DO THAT. Apart from blowing up the box, it may blow you up.
Thats what i thought, just checking. I was looking at old adapters i have and i have one that says Output: +12V -_--_- 3A Max would that still be too weak? I may have to buy one from amazon.ca if this one won't work.
 

djsfantasi

Joined Apr 11, 2010
7,842
Is DC 6-30V the input voltage or the output voltage? Your sketch is too vague. Can you add a close-up pic?

You're using a 12V 200mA supply, so the 8A rating is meaningless. 0.2A (200mA) input cannot supply 8A output! And you’ll need a supply that can supply several Amps output in order to heat up the nichrome wire.

If that is nichrome wire at all... In your picture, it looks like standard 24 gauge insulated hookup wire. Nichrome wire should be labeled as such on the spool and is always uninsulated.
 

sagor

Joined Mar 10, 2019
479
I tried it an I am successfully cutting foam!! Thanks so much for your help @AlbertHall and everyone else!
Though the 3A is working, check how hot that power supply gets, it may still be overloaded. If the power supply remains cool (or just warm), then you are probably ok with that supply. If it get quite hot, you need a higher current supply....
 

djsfantasi

Joined Apr 11, 2010
7,842
Though the 3A is working, check how hot that power supply gets, it may still be overloaded. If the power supply remains cool (or just warm), then you are probably ok with that supply. If it get quite hot, you need a higher current supply....
And if while cutting, the wire catches and/or slows down, you need a higher current owner supply..
 

shortbus

Joined Sep 30, 2009
8,817
Most of the reputable sellers of things like this use low volt AC not DC to power the wire. Like from a HVAC control transformer, they are 24V AC output and available from any big box store. The length of your nichrome wire also plays a part in it's heat from any power supply voltage or current.
 
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