Subject: Mig welder experience

From: [email-masked] (Paul Amaranth)
Date: 22 Nov 1993 14:33:59 GMT

There was a discussion on Mig welding on a car mailing list I'm on.
I sent this in and thought it might be of some interest here as well.
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After a lot of thought, and some trepidation, I bought a 175 amp MIG
from Harbor Freight the other year (that's one way to get the duty
cycle up on the low range :-).  Overall, I would not do it over.
The first thing that came up was the wire feed drive wheel was not
concentric.  This caused the feed rate to vary.  This was not too serious
at high rates, but was disastorous when trying to weld thin stuff.  I
finally cut the wheel down on my lathe and improved things to where they
were tolerable.  Still, the entire wire feed mechanism was pretty shoddy
(another example: the motor was pretty loose, when I tighted it up, it
started to bind with the gear train and wouldn't run at all).  The
torch is also not terribly good and the tips have to be ordered from
HF.  There are apparently a number of different tips which they get mixed
up.  I was not very happy; I should have sent it back on the next truck.
The other interesting point was the motor drive was run from the output
of the welding transformer, which means that the speed varied with the
heat setting.  Pretty tacky.

Instead, I did it the hard way.  I built a new wire feed mechanism
using a feedback pwm controller and added a Tweeco No. 1 torch.  Now it
runs 0-600 inches/minute with a calibrated dial and I can get tips at
the corner welding store.  In fact, I finally got this thing together
over the weekend.  Previously, the lowest heat setting was useless; now
I can lay a nice bead on 20ga sheet.  Was it worth it?  No, I should
have spent the money on a Lincoln or Miller unit in the first place
(I've probably spent the equivalent, if not in money, then in time).  I
could have spent all that time fixing my cars, rather than fixing the
welder.  On the bright side, I know more about MIG welders than I ever
cared to :-)  If anyone is masochisticly intersted in doing something
similar, I'd be happy to share my design notes.

-- 
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