Finished up my kinetic sculpture at 6:30 AM last Saturday morning.
Made it to the race by 8:30. (Photos available at:
http://www.kineticists.org/Community...s/Default.aspx)
Sound familiar? Good news though. By the end of the project I was
making fairly proficient looking welds in 1" and 3/4" EMT with my
Harbor Freight O-A torch. I think I finally discovered the secret.
Hold the torch back a few inches until the steel heats up some, then
move in. Concentrate on the continuious tube in the joint first to
avoid burning the edge of the butting tube. Start the puddle, add a
drop of filler rod. Then use the torch flame to move the puddle over
to the butting tube. As soon as a spot starts to melt on the butting
tube, play the torch so that the two puddles join. Its kinda like
playing with droplets of water on a glass. The molten droplet of steel
in the puddle will follow the heat of the torch. Once the two puddles
have merged into one and are connected to both tubes, work the torch
forward by moving it in semi-circles back and forth at the edge of the
puddle. Add filler rod consistantly. Watch the angle of the torch to
the joint. It makes a huge difference. Once you get a good puddle
going in steel of this size, you can sort of zip the joint closed.

This would all be easier with better equipment. My torch never seems
to stay in adjustment for more than a minute or two at a time. I found
that welding 1/4 of the joint at a time was the best way, and
alternated between joints on the frame of the project to control
warping. I did get some, but not bad. Now I just need more practice.
And larger tanks. I'm running a "B" tank of Act. and a 40cu/ft of Ox.
That's fine for a small joint here or there, but for a project of any
size, they are way too small. Mine were lasting 45 minutes to an hour
each, and I went through three sets. Maybe its time to upgrade to
75's.

One more thing, be concious both of where your flame goes after
hitting the tube and of what's still hot after you finish a joint. On
several occasions, I wondered whose steaks were burning for several
seconds before realizing that I was roasting my own glove.

Harry