Hi, Has anyone considered induction heating for the extruder? I'm interested to see if wrapping 50 to 200 windings around the head and passing 20vac or so through it generates enough heat in the extruder... 12Vac@1A / 50 windings = 0.24Vac@50A around the circumference of the barrel. Common switchmode chips like the tl494 and sg3525 could probably be used to regulate the temperature. Perhaps we could also check out soldering iron barrels? they're designed to stay at up to 400c for long periods of time. https://reprap.org/forum/read.php?70,8467,8467#msg-8467 Wed, 22 Jul 2026 00:34:32 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?70,8467,10995#msg-10995 https://reprap.org/forum/read.php?70,8467,10995#msg-10995 r2kordmaa Plastic Extruder Working Group Sat, 12 Apr 2008 16:54:22 -0400 https://reprap.org/forum/read.php?70,8467,10656#msg-10656 https://reprap.org/forum/read.php?70,8467,10656#msg-10656
My only concern is attaching the thermistor in such a way that it doesn't get fried by the magnetic fields]]> Triffid_Hunter Plastic Extruder Working Group Fri, 28 Mar 2008 19:41:08 -0400 https://reprap.org/forum/read.php?70,8467,10644#msg-10644 https://reprap.org/forum/read.php?70,8467,10644#msg-10644 blog.makezine.com]

An induction heater:
[www.penguinslab.com]
The schematic is on this page
[www.penguinslab.com]]]> Anonymous User Plastic Extruder Working Group Fri, 28 Mar 2008 12:30:36 -0400 https://reprap.org/forum/read.php?70,8467,8480#msg-8480 https://reprap.org/forum/read.php?70,8467,8480#msg-8480
The advantages are:-

No high temp insulation required.

The heat is generated directly in the outer layer of metal of the nozzle so less thermal resistance between the heat source and the polymer.

Less thermal mass so a faster response.]]> nophead Plastic Extruder Working Group Tue, 15 Jan 2008 12:33:33 -0500 https://reprap.org/forum/read.php?70,8467,8479#msg-8479 https://reprap.org/forum/read.php?70,8467,8479#msg-8479 Assargadon Plastic Extruder Working Group Tue, 15 Jan 2008 12:02:21 -0500 https://reprap.org/forum/read.php?70,8467,8476#msg-8476 https://reprap.org/forum/read.php?70,8467,8476#msg-8476
Good luck with the scavenging. I recently stripped a scanner, a printer and a couple of 8" floppy drives. The floppy drives being more than 25 years old had some nice steppers and loads of optos. The printer and scanner, being more modern, were pretty disappointing but the surprise find in the printer was a small peristaltic pump.]]> nophead Plastic Extruder Working Group Tue, 15 Jan 2008 08:26:13 -0500 https://reprap.org/forum/read.php?70,8467,8474#msg-8474 https://reprap.org/forum/read.php?70,8467,8474#msg-8474
See [sound.westhost.com] if you do want to try it out

I have an arduino on the way, and several printers from which to scavenge parts :)]]> Triffid_Hunter Plastic Extruder Working Group Tue, 15 Jan 2008 07:05:25 -0500 https://reprap.org/forum/read.php?70,8467,8471#msg-8471 https://reprap.org/forum/read.php?70,8467,8471#msg-8471
Its not quite as simple as you imply. If you put 50A through a good conductor like brass that is 1.5mm thick it will not get very hot. For non ferrous metals you have to use high frequencies to exploit the skin effect so that the current only flows in a thin layer at the surface.

You need to generate something around 20-50KHz at a around 20 - 30W I would guess. A 12V supply is a bit low to do that very efficiently. I have plenty of higher voltage supplies but it is a goal of RepRap to able to run from a car battery or a PC power supply.

Another problem I anticipate is that it may induce a lot of noise onto the thermistor so some filtering may be required there, or else turn it off momentarily to take a reading.

All in all it starts to look like a sledgehammer to crack a nut. The nichrome heater works well and is very simple and cheap. Is only the JBWeld that has problems with high temperatures. BBQ paint has been reported to solve that problem.

Not sure about soldering iron barrels. Do you know of a 12V one which has a hole all the way through?]]> nophead Plastic Extruder Working Group Tue, 15 Jan 2008 05:23:29 -0500 https://reprap.org/forum/read.php?70,8467,8467#msg-8467 https://reprap.org/forum/read.php?70,8467,8467#msg-8467
Has anyone considered induction heating for the extruder?

I'm interested to see if wrapping 50 to 200 windings around the head and passing 20vac or so through it generates enough heat in the extruder... 12Vac@1A / 50 windings = 0.24Vac@50A around the circumference of the barrel.

Common switchmode chips like the tl494 and sg3525 could probably be used to regulate the temperature.

Perhaps we could also check out soldering iron barrels? they're designed to stay at up to 400c for long periods of time.]]> Triffid_Hunter Plastic Extruder Working Group Tue, 15 Jan 2008 03:20:25 -0500