On Wed, 14 Jul 2004 22:14:16 -0700, "william_b_noble"
wrote:

resistance solder units that I have output between 1 and 2.5 V

"Wild Bill" wrote in message
...
I dunno much about the specific outputs/capacity of the resistance
soldering
units, but I'll throw a few observations into the thread.
The units that I've seen in use in a starter/generator repair shop were
fairly compact units with a transformer housing of about a 6" cube. The
plier/tweezer-style handpiece appeared to have carbon jaws that made the
contact to the joint to be soldered. The heat was rapid, and they used
heavy
gauge solder, 1/8" maybe.

Some butt welding machines that I used to repair were used to weld ends of
heavy steel wire together (similar to a bandsaw blade welder). The sizes
ranged up to about 1/4" diameter.
The secondary of the transformer was only a couple of turns of flat
braided
cable securely clamped at the ends. The cable was the type that was used
as
engine ground strap in autos decades ago. This stuff would be good for
using
as a secondary winding in a modified transformer, easy to thread thru the
frame aand flat for fitting into a square shape.
For insulation, a good product would be fiberglas tape.. thin, high temp
resistant and an effective barrier/insulator.

WB
.................

"Eric R Snow" wrote in message
...
Greetings to all the microwave oven scroungers,
I have a job coming up that requires soldering the corners of brass
frames. These frames are made of 1 1/2 x 1 1/2 x 1/4 brass angle. In
the past I've used a torch to heat the brass. This leads to a little
distortion. This can be troublesome because the brass expands so much
that it moves the joint even though everything is clamped. The parts
must then be straightened when cool. Because of the application and
fit the frames must be straight within .010" in 36". I saw some
resistance soldering units in a catalog and the description of how
they operate says that only a small area is heated and gets to heat
fast. This would be ideal. However, the ones I saw were too small and
the price too large for me. But I've got several microwave
transformers and they seem like they might be perfect. A rough
calculation from the specs and pictures given in the catalog leads me
to believe that they output about 12 volts open circuit. Some have
variable outputs. So I have a few questions:
1) Does 12 volts sound reasonable? Would a different voltage be
better?
2) Is DC better than AC? Does it matter?
3)What would be good ways to limit the current? Would a lamp dimmer on
the input side of the xmfr work? Wouldn't that also lower the voltage?
Would that matter?
4) I have a timer that pulses a relay on and off. I can set the length
of the pulses. Sort of what a lamp dimmer does but much longer pulses
(1 second and up) and the voltage would be the same out as in. But the
brass would average the heating. Would this work almost as well as
lowering the current? Better?
Any other input is much appreciated.
Thank You,
Eric R Snow,
E T Precision Machine



Thank You. That's just what I was looking for.
ERS