[TheForge] Induction Forge?

[Michael]

You can also pick up a lot of information by searching under induction
brazing.
Mikey

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Steve Smith
Sent: Friday, August 18, 2006 6:34 PM
To: Sponsored by ABANA
Subject: Re: [TheForge] Induction Forge?

This is pretty cool Ries. Thanks for the link.

So Frosty, why don't we do this?

There's been some discussion on rec.crafts.metalworking, looks like some 
on sci.electronics.design Use Google groups search. For instance:

Well, they have their problems, and are certainly not safe if you lean
to close and have metal fillings...
Seriously, though, I've played about with a 100W model using a modified
mosfet audio amp and an LC head consisting of about 15 turns of 16# wire
and a 1u 650V polyester cap (low esr), fed from a signal generator at
about 100kHz. The o/p of the amp was fed to the LC head through a
transformer made of a few turns of wire on a ferrite core designed for
switching power supplies. I kept it on resonance manually, using a
scope, but never quite got round to using a PIC to do the signal
generating and resonance point sensing.
The whole thing worked quite well, with a small screwdriver being heated
to red at an efficiency of about 75%.
A lot of fun, but some care needs to be taken and you have to know what
you're doing (esp if you don't know what you're doing).

Apart from exploding tooth fillings there are a couple of less obvious
hazards.
The first one concerns the heating coil. I usually just play around with
it in my hands, which is OK as long as you avoid  touching any high
voltage parts (although they seldom go above 120p-p in my design).
However, I have heard a story about someone who once did likewise, but
neglected to take of their wedding ring, which became red hot in about
half a sec.
Similarly, when putting down a running coil, don't forget about the
effect on any metal in the desk, bench, or whatever the resting surface
is.

Lindsay has a book:
http://www.lindsaybks.com/bks2/ind/index.html

Steve

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