The welds are looking up but still not great. I always seem to weld at the end of days after having done ranch work or skied so my arms and hands are kinda tired. Not that it’s an excuse (ok, maybe it is). I don’t yet have the ability to smoothly and consistently do 1/4 of the tube radius without getting too slack of an angle between the torch and the joint which blows the heat and argon past the tube making for an ugly and poor bead. I think that’s why I’m getting the bluish colors on the bead itself, and an outline around the bead when I end up tilting the torch too much. (Feedback anyone…?) In the meantime while I practice doing quarters, I start at the obtuse angle of the joint and weld around one way 1/8th of the tube, and then pause while letting off the foot pedal, reposition my hand, and then do the other 1/8th to do the 1/4 in a “paused first pass.” The 1″ x 0.035″ tubing from Aircraft Spruce seems to behave different than bicycle tubing of the same width and diameter for some reason, I just don’t know why exactly. I got it for making some straight-blade MTB forks but it’s great for welding practice too (cheaper than True Temper). The 1″ diameter of the tube also has a tighter radius than the larger tubing on most bikes which is good for practice but harder to keep the torch at a constant 70-80 degree angle to the tubing joint.
I have yet to find information on the web or through friends on how many “passes” they do on each of their welds. I think this is because the answer would be, like most things, “it depends.” I have been doing a non-pulsed first pass with filler rod to join the tubes. Then a ‘beautification” pass with the pulser and no filler rod to get a better stacked coin appearance since my first pass tends to be good, but not consistently good. I’ve noticed that the pulser also fills any gaps or volcanoes really nicely likely making my weld stronger since of better overall penetration. Of course, where my first pass was bad, the pulser will make it look better but will blow through any weak or thin spots pretty quickly. I’ve been trying out the below pulser combination on 0.035″-walled tubing and it seems to work pretty well:
Peak amps = 75 – 80; Base amps = 22; % of peak = 25; Pulse frequency = 2Hz.
With the frequency at 2Hz, I don’t dab the rod in the puddle so i haven’t been putting in any extra filler rod on the 2nd pass. I just move relatively quickly on top of the 1st pass. I have also laid the rod in the joint and used the pulser but I am not sure it needs more filler material after the first pass (…anyone got knowledge on this…?). I figure, if people who have years of experience welding do a 1st pass without filler and a second pass WITH filler, then the reverse should be ok too (?). As long as there is good penetration and not overheating, it should be good to go.
The other reason the answer number of passes is dependent on the situation, is because of frame alignment. If your frame is out of alignment after welding a joint, you can try to adjust the alignment by doing a second (or third) pass on one side to pull the frame into alignment. This is especially important while tacking of the frame. But overall, it’s better to cold set the frame after it’s all welded up since too many passes has the potential to weaken the joint by overheating.
Gonna just weld the frame up this weekend finally, ride it several times to see if the welds hold, see if the geometry is likable, and then dismantle and hang it on the shop wall until frame #2 is built. The first solo frame will never be perfect, i just gotta get it under my belt.