JohnM wrote:

Ignoramus25850 wrote:

Someone offers me a hobart mega-arc 300 with 200' of cable, tig torch,
ground clamp etc. Supposedly can be used for tig welding.

No HF starting.

Question, is that a good deal at $500.

It is a 3 phase machine, which does not bother me terribly too
much. If it demands more power than my 10 HP RPC can produce, I will
add another, second idler motor. These motors cost nothing, relatively
speaking, and can be kept in some unused corner. I would spin up the
first idler and only then start the second, and the load after that. I
have 60A in my garage, easily upgradeable to 75A.

Any thoughts?

i


That should be a pretty good machine, but he's asking a lot of money
for it. If the HF is the old fashioned sort, a cleaning of the spark
gap or replacement of the transformer should be all that's required, I
think any ordinary furnace lighting transformer would work fine.

Offer him $200, see what happens.

Can't be sure, I was thinking Ignoramus meant that it did not have the
HF system at all,
rather than it was not working. Anyway, you really WANT HF. Now that I
have
my Lincoln Square-wave TIG 300, I can't imagine using anything without HF.
And, you will have a horrible time doing Aluminum without HF. Since it is
a 3-phase machine, it either has to be an inverter square-wave system, or DC
only. You can do practically anything BUT aluminum with DC. The whole
reason
I got a square-wave machine was to have aluminum capability. (And, my whole
system of acquiring tools was to get only ONE of any type machine, and
always
try to get the most versatile machines I could.)

Jon

On Wed, 07 Sep 2005 17:57:45 GMT, Ignoramus11916
wrote:

On Wed, 07 Sep 2005 11:06:15 -0400, JohnM wrote:
Ignoramus25850 wrote:
Someone offers me a hobart mega-arc 300 with 200' of cable, tig torch,
ground clamp etc. Supposedly can be used for tig welding.

No HF starting.

Question, is that a good deal at $500.

It is a 3 phase machine, which does not bother me terribly too
much. If it demands more power than my 10 HP RPC can produce, I will
add another, second idler motor. These motors cost nothing, relatively
speaking, and can be kept in some unused corner. I would spin up the
first idler and only then start the second, and the load after that. I
have 60A in my garage, easily upgradeable to 75A.

Any thoughts?

i


That should be a pretty good machine, but he's asking a lot of money for
it. If the HF is the old fashioned sort, a cleaning of the spark gap or
replacement of the transformer should be all that's required, I think
any ordinary furnace lighting transformer would work fine.

No, it is supposed to be the "new sort", with more electronics and
lighter. Also comes with 200 feet of welding cable and tig gun and
stinger.

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.


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).

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

Not likely.

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

Ignoramus11916 wrote:
On Wed, 07 Sep 2005 11:06:15 -0400, JohnM wrote:

Ignoramus25850 wrote:

Someone offers me a hobart mega-arc 300 with 200' of cable, tig torch,
ground clamp etc. Supposedly can be used for tig welding.

No HF starting.

Question, is that a good deal at $500.

It is a 3 phase machine, which does not bother me terribly too
much. If it demands more power than my 10 HP RPC can produce, I will
add another, second idler motor. These motors cost nothing, relatively
speaking, and can be kept in some unused corner. I would spin up the
first idler and only then start the second, and the load after that. I
have 60A in my garage, easily upgradeable to 75A.

Any thoughts?

i


That should be a pretty good machine, but he's asking a lot of money for
it. If the HF is the old fashioned sort, a cleaning of the spark gap or
replacement of the transformer should be all that's required, I think
any ordinary furnace lighting transformer would work fine.


No, it is supposed to be the "new sort", with more electronics and
lighter. Also comes with 200 feet of welding cable and tig gun and
stinger.


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?

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

thanks John...

i


The last statement is the question; how much are you going to ask from
the machine? Try it out, it'll either suit you or it won't, no big deal
either way.. I'm guessing you'll find it's more than adequate.

HF *should* be easy to repair, regardless of the age of the machine, but
there's sure no guarantees. Go over and ask on sci.eng.welding, I think
there's some guys there who don't hang out here, one of them may have
dealt with that very machine.

John

On Wed, 07 Sep 2005 11:06:15 -0400, JohnM wrote:


That should be a pretty good machine, but he's asking a lot of money for
it. If the HF is the old fashioned sort, a cleaning of the spark gap or
replacement of the transformer should be all that's required, I think
any ordinary furnace lighting transformer would work fine.

This is not a good idea!

Don Foreman wrote:
On Wed, 07 Sep 2005 11:06:15 -0400, JohnM wrote:



That should be a pretty good machine, but he's asking a lot of money for
it. If the HF is the old fashioned sort, a cleaning of the spark gap or
replacement of the transformer should be all that's required, I think
any ordinary furnace lighting transformer would work fine.


This is not a good idea!

I haven't replaces a HF transformer with one from a furnace, but I've
opened up a few old welders to blow them out and the transformer looked
for all the world like the furnace ignitor type. I think I remember two
Hobarts that had those transformers.. If there's a fundamental
difference between the two I'd certainly be interested in knowing it,
the more I know the better off I am.. I think...

John

Ignoramus25850 wrote:
Someone offers me a hobart mega-arc 300 with 200' of cable, tig torch,
ground clamp etc. Supposedly can be used for tig welding.

No HF starting.

Question, is that a good deal at $500.

It is a 3 phase machine, which does not bother me terribly too
much. If it demands more power than my 10 HP RPC can produce, I will
add another, second idler motor. These motors cost nothing, relatively
speaking, and can be kept in some unused corner. I would spin up the
first idler and only then start the second, and the load after that. I
have 60A in my garage, easily upgradeable to 75A.

Any thoughts?

i

For my nickel, a DC only machine without HF and 3 phase input that is
hard to get parts for? I would offer him a case of beer and hauling it
out of his shop. $500 will get you lots more useful machines if you have
interest in alumuinum or TIG welding.

As for building your own inverter, Don is right. That is a serious
project and by the time it is working well, it would have been cheaper
to buy a Miller Dynasty!

Save your money,
Bob