welding technique for clusters

Hello everyone.

I've been practicing. Tubemiter has generated a working set of
templates, The angle grinder and my dad's 1/2 round tripple-cut
******* were given a thorough workout. I even made a pilgrimage to H-F
on Saturday and picked up a tubing notcher. (Do those (insert slur of
your choice) really have to coat every damn thing they sell in
Cosmoline and machine oil?) Suffice to say that I've got a good handle
on how to cut and fit tubing into clusters. I could use more practice,
but I've got the basics down cold.

Now, here's the question: Assume I'm about to weld a commonly-
occurring cluster in the side of a Pratt-truss. Upright joins longron
at 90 degrees. Diagonals join either side of the cluster at 45
degrees. This is a flat cluster. Everything would appear as if you
laid it out on a table using a jig.

Where should I tack the joints? Does it matter?

Assuming I've now tacked the joints, Where should I start the bead and
which is the preferred direction of travel? I started on the face of
the cluster where the points of the three tubes come together and
welded into the "crotches" of the joints. Everything went well until I
tried to close up the remaining 1/8" and make the two beads meet.
There things got kinda screwy. I had trouble getting the puddle
started. The rod kept flowing onto one tube or the other but not both,
etc. I ended up adding A LOT of rod that I'm sure the joint didn't
need.

Suggestions?


BTW: The tubing is 3/4" OD conduit with the zinc etched off using
VeeDubber's muratic acid method. I'm using 3/32" RG-45 rod and a #0
tip on my H-F torch. Gas pressures are 3-4 psi each. Neutral flame
with just a trace of feather.

Harry Frey
wood, cotton, and now steel guy