welding (was: Tranny woes)

[treed2 at wsu.edu (T. Reed)]

Hmm, unfortunately I left all my notes and papers in Seattle; I'll be
going back that direction in a few days and I can take a look, tho.

If you're welding, say, 1/8" wall tube, current setting is easy (your
welder should have a chart converting between current and metal
thickness). Feed rate requires some experimentatinon - you want to start
with probably about an inch per second. Since the electrode burns off as
it goes, you will loose the arc completely if you have too slow of a rate,
and you'll drip molten metal on yourself if it's too high (to a point;
after that it will just short out). If you don't feel confident, get some
scrap tube, cut it up in to 10 or 15 pieces and practice welding them
together until you get the right settings.

As far as doing circular tube, you're going to have a real hard time
trying to seam weld pieces together "in the car". I would start by
installing the frame (I'm assuming you're talking about the twin here) and
doing two tack welds at each junction (try turning the current down a
notch to keep them from being super ugly), then pulling the frame out and
finishing the welds out of the car. Do 1/3 of the circumference at a time,
unless you have a way to spin the whole contraption with one hand while
you're working. A left and right zig-zag motion works best for me, but it
kinda depends on your forearm muscle development. If there is almost no
gap between the pieces and you have a steady hand, you can usually get
away with just a slow, straight line along the seam. Easier to screw up
with that method, tho.

If you don't already have an auto-darkening face shield, I'd recommend
getting one. If you're a cheapass, Harbor Freight has them for ~$60. Get
the one that does #4 (or is it #6) to #14 controllable by the dial on the
side. Get some tacky putty (poster putty works well) and stick it on there
after you get it set right (#10-#11 is where I usually leave it) so you
won't accidentally spin the dial while flipping the shield up and down.

I can still see, heh.

If you're building a space truss type of thing, you have another problem
which is fitting the pieces together since they usually meet up at some
odd angle (and there's a problem even at 90 degrees!). You have to cut a
semicircle out of the end of the leg half of a 'T' joint, and you have to
cut even weirder shapes for other angles.

I didn't really get any good instruction in this area; the only thing I
remember him saying was that he used some sort of hole saw bit to do the
90 degree cuts.. but that it chewed up the bit real fast and everything
had to be clamped down excessively.

HTH a little,

-Toby

On Fri, 12 Dec 2003, Allyn wrote:

> got any quick notes from that class... for say... mig+gas?
> i havent been able to find a good general guide as to adjusting settings
> (current and feed rate), as well as good techniques to use when welding from
> all angles (around seams of joining tubular steel sections together).
>
> Al