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How do pulse welders work?


#1

Hi,

New question. Just how do pulse welders work for small (earring
sized) welding?

In other words, just how many volts and amps for how many seconds
would I need? And is it just on-off DC, or is it an RF pulse. What
does the envelope look like.

Could someone hook up an oscilloscope or a voltmeter (NOT directly,
use a voltage clamp!) and examine tell me what the output is?

I’ve got lots of electronic parts that have been begging to be used
for years. I’m might sell my equipment and junk box to a ham so I can
make room for jewelry supplies.

Andrew


#2

Wow, that is a lot of question. Why not start here

http://www.ganoksin.com/gnkurl/1l6

You will soon see that there is a lot more to this technology then
you may have imagined.

Bill
Reactive Metals Studio, Inc


#3

Hi

I did some more research into duplicating a pulse welder.

The central principle is to apply a pulse of low voltage high
amperage AC. This can be easily done at low cost (and great hazard)
with the help of a microwave oven step-up transformer re-purposed as
a step down.

Google “MOT-spot-welder” at Instructables.

I think I could use this by itself to fuse fine silver, but I think
I’d put a few extra things around the naked transformer if I could
for the sake of safety.

Central to this would be a bank of super capacitors connected in
series-parallel. I’d isolate the bank from the rest of the world
using a single-pole double throw switch.

On one side of the switch, I’d connect the line voltage through a
step-down transformer to a rectifying system to trickle charge the
capacitor bank at 12 volts DC.

The other side of the switch, I’d connect the 12VDC bank to an
off-the-shelf power inverter. The inverter would then create 117V
switched AC to be applied to the repurposed microwave transformer.

If I want dial-in precision for repeatability, I could replace the
single pole double pole switch with relays.

Andrew Jonathan Fine


#4

Andrew,

The central principle is to apply a pulse of low voltage high
amperage AC... Central to this would be a bank of super capacitors 

I think you mean DC? Applying an AC current across a bank of
capacitors will get you nowhere except out of phase.

Also, what you are describing is a resistance welder, not a pulsed
arc welder. For a pulse welder you need a shielding gas and a
tungsten electrode. And of course some way of shaping the “pulse”.

To weld silver you will need amperage control, as it needs a lot of
heat (read amperage) as it is terribly conductive and will dissipate
it quickly. The more it dissipates the larger your puddle will
become until the whole piece drops out on you.

I can be done, but you might as well learn to use your torch first.

Scott