Listers...
A week or so back we had a thread going on Mig welders and techniques
for LBC restoration. I mentioned trying to find one of Ray Gibbon's
old posts on the subject as I remember it being very well done.
Here it is then...I'm sure Ray won't mind us sharing it again.
Date: Tue, 23 Nov 1993 11:18:45 -0500 (EST)
From: "W. Ray Gibbons" <gibbons@northpole.med.uvm.edu>
Subject: Welding, bugeye parts
Alex Levinson wrote regarding welding and parts for his bugeye.
On welding: Are those who say MIG welding is easy being disingenuous?
Maybe a little. It is easy in comparison with other ways of welding
I've tried, but not as easy as drawing a line with a magic marker, as
one restoration text said. I agree, it is easy to burn through when
butt welding 20 gauge sheet metal. If you teach yourself MIG welding
by trial and error, there will be a lot of errors. If somebody who
knows how stands beside you and tells you how to do it, it will get
easier. I have sold a couple of welders (at no personal profit) to
friends by proving they can weld a good bead the first time if I set
up and show them how to do it. I suspect A.L. used the same trial and
error, weld, grind, weld again method that I did.
Jump off now, if you are sick and tired of hints from an amateur
welder.
Hints:
Metal must be CLEAN. MIG does not work well on rusty or painted
metal.
The two pieces to be joined should be in contact, to equalize heating.
The books say to leave a slight gap. That's ok with 1/8 in steel, but
it only causes problems (IMHO) when welding sheet metal.
Butt welding light sheet metal is challenging, I agree. To minimize
burn through, have the best contact of the edges possible and--this is
important--weld in short bursts so the puddle gels between trigger
pulls.
High buck welders have a stitch mode that does this automatically,
those affordable by hobbiests will do the same thing if you just keep
pulling the trigger. If you try to butt weld a continuous seam on 20
ga without letting the puddle cool, the heat keeps increasing. You
either have to be skillful enough to adjust arc length and travel
speed (hard) or keep pausing (easier) to avoid burn through. You will
want to do this for other reasons, too. If you try a continuous weld,
or even stitch welding without cooling periods, the panel will heat up
and may warp. Not much problem on floor pans. On exterior panels
that must not warp, weld 1/2 inch here, 1/2 inch far away, 1/2 inch in
the middle, etc, with air or damp rag cooling between welds, until all
those 1/2 inch segments are a continous bead.
When you can, use a flanger (brit. Joddler) to make an offset on one
panel, lay other panel on top, and avoid the hassles of butt welding.
That gets MUCH easier. Other hints above still apply.
Heat and wire feed are only the most obvious adjustments. If the
torch moves closer to the work, the heat increases. Ditto if the
travel speed decreases. Strive to keep these constant, or change them
only deliberately.
If welding dissimilar thicknesses (e.g. floor pans to inner rocker),
point the torch toward the thicker piece as necessary to heat both
evenly, or zig-zag torch across the join dwelling on the thicker
piece. (If you do not have intimate contact between the parts, it
will be exquisitely difficult to weld parts that are substantially
different in thickness.) In general, think about heating of two
pieces--for example, when welding a small patch into a panel, the
patch will heat fast and the panel more slowly. Adjust torch angle
and movement to compensate.
Big, huge, most important hint of all. You can't do a good job of
welding when you can't see what you're doing. Once in a blue moon you
may want the hand held eye screen that comes with some cheap welders,
but you should also buy a decent hinged helmet. Then save the glass
(intended to protect 8 hr/day production welders) that comes in it for
solar eclipses.
Replace it with a gold coated glass (not sure of exact term, but
welding store will know). You can adjust the hinges on the helmet so
you can place the torch, using both hands if necessary, and nod your
head to lower the shield (looks real professional). Trouble is, your
eyes take a few seconds for the iris to adjust, so you cannot see the
beginning of the arc. For really critical stuff, I beam a 600 watt
bulb on the work so I can set up through the lens with the faceplate
down; it also helps me to see things. If you cannot see the edges to
be joined as well as you would like, draw a line along the intended
weld with a soapstone marker.
I also wonder at those pictures of guys free-handing a torch. You see
them waving the torch around, but I bet that's not how they got the
welds that are shown in close-up examples. I invested in a couple of
machinists magnets and a piece of angle iron. When possible, I attach
the magnets to the car, lay the angle iron across the magnets, and
rest my hand on that.
One can also rest the edge of the torch on the work at a slight angle,
and the arc is about right. Or use the sign-painters method with a
wooden stick and a rubber ball (a picture would be worth 1k words).
Re welders. I have a Lincoln SP-100. It is pricier than the imports,
but has continuous adjustment on both the wire feed and heat, a 3 yr
warranty, and parts available at the corner welding store. Butt welds
in 1/8 steel push this machine, but it can do anything on a Spridget.
It is a good quality machine.
Ray Gibbons
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Cheers!
Tom O'Malley in Southbridge Massachusetts
'74, '77 Spits
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