Can you use a regular ac buzz box welder as a spot welder for sheet
metal.I plan to make a clamp with copper alloy electrodes.Anything
special with the electrics on a commercial model spot welder?What would
be the amperage to spot weld 1 mm sheet metal if my idea has merit.

Time Traveler wrote:

Can you use a regular ac buzz box welder as a spot welder for sheet
metal.I plan to make a clamp with copper alloy electrodes.

Doubt it.

Anything
special with the electrics on a commercial model spot welder?

Yes, sadly.

What would
be the amperage to spot weld 1 mm sheet metal if my idea has merit.


Don't know, lots. Little spot welders just don't cost that much. The HF one
works, it just isn't as nice as a Miller. I have borrowed an HF spotwelder, and
I owned a Miller for awhile, that's how I know. You need a whole lot of current
for spotwelding, so unless you wanted to completely rewind the transformer on
that buzzbox I doubt it would work.

GWE

Correct me if I'm wrong but I think spot welding involves a very short burst
of heavy current. It is a sort of one shot affair, and nothing you could
duplicate with a buzz box

Bob Swinney
"Time Traveler" wrote in message
...
Can you use a regular ac buzz box welder as a spot welder for sheet
metal.I plan to make a clamp with copper alloy electrodes.Anything
special with the electrics on a commercial model spot welder?What would
be the amperage to spot weld 1 mm sheet metal if my idea has merit.

No, you cannot do a standard spot weld using a buzz box. The current for
a spot welder runs in the several thousand amp range at less than a
volt. Your buzz box runs at 25 volts and the usual couple hundred amps max.

There are some very nice portable spot welder units that do a nice job
on steel up to 1/8" total thickness (110volt) or a bit more (230volt
units).
http://www.harborfreight.com/cpi/cta...emnumber=45689

You can also get an accesory tool (Eastman Tools???) that sets a rod
down, does a puddle, and retracts. It's actually a standard stick weld
but in a round button form.

Time Traveler wrote:
Can you use a regular ac buzz box welder as a spot welder for sheet
metal.I plan to make a clamp with copper alloy electrodes.Anything
special with the electrics on a commercial model spot welder?What would
be the amperage to spot weld 1 mm sheet metal if my idea has merit.

Reading the specs on a commercial spot welder for 115v it says output is
40 amps.Am I missing something from this spec?

Time Traveler wrote:
Reading the specs on a commercial spot welder for 115v it says output is
40 amps.Am I missing something from this spec?

I expect you are missing something. What does it say the voltage is?
Spot welders are usually less than 5 volts so with a 40 amp output the
power would be about 200 watts or less.
Not as much as a big soldering iron.


Dan

Not sure where you are getting those specs from. The small portable 115
volt units are rated at 1.5kva (1.5 kw) so expect 12.5 amp input current.

Page 10 of the Horrible Freight 115 volt spot welder
http://www.harborfreight.com/cpi/cta...emnumber=45689
shows amperage in the 2000 to 4000 amps range
http://www.harborfreight.com/manuals...5999/45689.pdf

The larger stationary units for industrial use are typically in the 15kw
and up (WAY up!).

Time Traveler wrote:
Reading the specs on a commercial spot welder for 115v it says output is
40 amps.Am I missing something from this spec?

You can make an equivalent weld by drilling a hole in one of the pieces
and filling it back up with weld metal. It works pretty well with MIG,
at least. The manual for the truck I was repairing said to disconnect
the battery ground to protect the computers.

Jim Wilkins

Thanks guys for the help.Looking further on the web it seems the output
voltage is around 4-5 volts as some posts stated.There is also a
schematic for a homebrew unit that looks interesting.One site stated on
AC volt-ampere ratings to derate the VA by.66 as they are rated in
apparent power.This is to allow for any capacitive or inductive
reactances.Trying to find a surplus xformer to rewind the secondaries
for the homebrew unit.Thanks again.

Search on Microwave oven transformers. They might be just what you
are looking for.
Locally I can buy microwave ovens at St. Vincent de Paul for a dollar
or two. They are non working, but seem to have good transformers.


Dan

From the size of the xformer used on the homebrew spot welder it looks
big.It uses 4 gauge wire (4-5 turns) on the secondary.Don't think any
home microwave xformer would work.Will check the specs on microwaves to
see if I can use them on other projects in the future.Thanks for the
help.

I measured a microwave oven transformer. The window for the secondary
is .890 inch by 1.65 inch.
You might be able to get 8 turns of # 4 welding cable for a secondary.

Dan

Worth a look to see about the microwave option.Thanks again.