Subject: Relative merits of MIG vs. oxyacetylene

From: [email-masked] (Harold Levie)
Date: 10 Mar 1994 01:52:43 GMT

The recent thread on MIG vs oxyacetylene included one comment that bears
amplification: MIG is easy _once_you_have_the_settings_ for the particular
job. That said, I will point out that I have no real experience with MIG, 
considerable with AC and DC stick welding, and even more with O/A. One of the 
great virtues of O/A for small, one-of-a-kind jobs (especially repairs) is that
it is a relatively slow process. Some skill is required, to be sure, but it 
seems not to fade quickly between exercises and is great fun to acquire. 

I am indebted to a former colleague who was a superb metal sculptor; he gave
me a 15-minute introductory lesson and the advice to get a welding set and 
plan on expending three sets of cylinder refills as tuition. According to him, 
taking up metal sculpture (meaning, in my case, welding for the sake of 
welding) is the one sure route to skill--if you only weld what _has_ to be
welded, you will never have enough confidence to take on more than the 
simplest jobs. (This probably accounts for the enormous number of dormant
welding sets that I have seen, and to some extent for the frequency with
which they appear in the want ads.)

Once the requisite skill is acquired, the range of jobs suitable to an O/A
set is impressive; I have been known to build airplane mobiles out of #10
steel wire, _braze_ broken cast iron parts for a rototiller (try that with
a $100 MIG!), repair auto exhaust systems (on and off of various cars...) and 
build dip tanks from the sheet metal salvaged from an old washing machine. It 
is nice to be able to heat stuff for bending, loosening, or shrink fitting, 
and I have even found that it is possible to do a respectable job of hardfacing
by using a stick electrode with the flux broken off. 

Granted, multipass thick welds on heavy sections are a chore best left to
a stick welder, and if I were doing a large volume of welds under similar
conditions (building a trailer, for example) I would almost certainly opt
for MIG. But for the occasional repair job, my first inclination is to 
consider torch welding---the situations where I chicken out are usually cases
where warpage (the _real_ bane of O/A welding) would be a problem, not where
the thickness of the metal is an issue. 

One bit of advice: I found that at least one of the less-expensive brands
of torch (Harris Calorific) was _very_ difficult to use, because the tips
would only produce a non-turbulent flame over a narrow range of flow rates.
Replacing the Harris torch with Victor (a full-size and one of the J-series
``aircraft'' torches) made a world of difference. YMMV