On Wed, 07 Sep 2005 23:03:45 GMT, Ignoramus11916
wrote:

On Wed, 07 Sep 2005 16:16:45 -0500, Wayne Cook wrote:
On Wed, 07 Sep 2005 17:57:45 GMT, Ignoramus11916
wrote:


Probably a good machine but parts are almost none existent for these
old Hobart welders. If it has square wave AC capability then it would
probably make a pretty decent TIG welder. If not then aluminum
capability is going to be ok but not as good as the newer welders.

It is from mid 90s and does not have AC capability.

Ok. Still hard to get parts for since Hobart got split up in the buy
out.


Offer him $200, see what happens.

A 10 hp convertor should power this machine well.

My calculation, based on 300 amps at 40V, gives me energy consumption
at least 12 kW. That's a little bit too much for a 10 HP RPC. Am I
mistaken?

No you're not mistaken. Mine takes 80 amps single phase to run full
out (though I've only got it on a 60 amp breaker).

Yep.

I doubt that I will need 300A very often though, although I have no
idea.

Not likely.

So, Wayne, what can I weld with such a welder?

Steel, stainless steel, actually in one form or another it would be
capable of most metals even aluminum. Just not in the most efficient
way.

Without HF you would be limited to scratch start TIG (if you'd kept
the arc stabilizer it would of fixed this problem). The real problem
with this is tungsten contamination. However it's been done this way
for years and is certainly doable.

Aluminum is most efficiently TIG welded with a square wave machine.
The good ones allow adjustment of frequency of the AC, and percentage
of cleaning verses heating polarity in the square wave (I know not
proper terminology but it's the clearest way of describing the actual
end product that I can think of). Next would be sine wave AC with HF.
It was the only method available for years and does work but requires
some more skill. However TIG welding aluminum started with reverse
polarity DC. The drawback here is that it puts so much heat into the
tungsten that you need a large torch and tungsten to do any real
thickness of aluminum. In truth sometimes reverse polarity DC is
better than AC. It has a much higher cleaning action for really dirty
aluminum. I've used it in the past a few times on troublesome
castings. But it really blasts the torch and tungsten to do it.

Most other metals will DC TIG just fine on straight polarity so the
only thing you'll have to watch out for is contaminating the tungsten
when you start.

This welder will likely make a superior stick welding power source.
Depending on the controls it has may well be one of the best stick
welding power sources out there in terms of wide range capability. I
can make my old CyberTIG 300 weld thin metal with small rods better
and easier than with any other power source I've ever used. Yet it's
also able to weld with large enough rods for 99% of anything I need
and will certainly be large enough for your needs.




Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm