For many years I have wanted to learn how to weld and now that time has come.
When I was a little kid I saw some guys building a metal staircase in the
back of a house in my neighborhood. I stopped to watch but one of the
workers told me I shouldn't look at it because it would damage my eyes.
When I was a teenager I was sitting on a ski lift in Pennsylvania and I
looked up to see how the chair was connected to the cable. A bracket was
hooked on the cable and top of the chair was welded to this bracket. It
looked strong. I figured that if that chair lift was going to fail, it was
going to be for some reason other than the failure of the weld connecting the
chair to the bracket.
Recently, I found a big variac in the trash. It had a toroidal transformer
core about 30cm in diameter, with a core cross section of about 8cm x 8cm.
The specification plate said that it was intended for 220V input and 6KW
maximum power. Although it seemed like a shame to take apart the precision
wiper mechanism of the variac, I wanted the thing to be useful, and I really
didn't anticipate any need for a big variac. So I decided to make it into
a welder.
I bought some #6 wire from an electrical supply place and wound a secondary
on top of the existing winding. Thus, the variac became
a regular fixed transformer with approximately 175 turns of #12 wire on the
primary and 46 turns of #6 wire on the secondary. The primary is connected
to 220-Volt wall power through a 25 Amp fuse. The secondary wire is a bit
longer than it needs to be for 46 turns, so the 2m extra at either end is
used as the welding wire, instead of cutting it off, making terminals,
and attaching welding wire to the terminals.
At one end of the secondary
I attached a welding rod holder that I bought. A welding rod holder is
really just a big alligator clip. It is very similar to the clip used
on automobile jumper cables. But welding rod holders have notches that
help hold the welding rod securely in their jaws. At the other end of the
secondary, I just left it bare wire, with about 4cm of copper exposed. This
is connected to the work that is to be welded by clamping it with a C-clamp.
I didn't know that there was a big range of possible welding rods. The guys
at my local hardware store sold me some 6013 rods, which are apparently
general purpose rods. This means that they can be used with DC or AC welders.
Obviously my welder is an AC welder. People say that DC
welds better, and if I can find some high-power rectifiers I will try it.
I fooled around with the welder, trying to join some old pieces of L-section
steel from a bed frame. It didn't work very well. It was hard for me to
know whether the problem was me or my welder. Recently a professional auto
mechanic offered to teach me how to weld. I took him up on that offer
and although he has a MIG welder which he prefers, he said that it is
quite possible to get good results with an AC stick welder, and he
demonstrated. The mistake that I was making was that I wasn't getting the
work hot enough. Also, he showed how the "sweep" across the joint helps to
make a smooth, strong weld. I went home and practiced. After a couple of
hours of practice, I could make strong welds, but still not pretty.
Hopefully, with experience, smooth, even welds will be possible.
Movie of my friend Darius practicing welding with the welder I built
me welding (equipment visible lower left)
testing the strength of welds
