I have two types of joints.  In one location I have a tube within a tube to   reinforce where two tubes meet.   In that area I mayl be installing an axle   perpendicular to the tubing.   With chromolly I was going to drill the axle   assembly into the center of the tube.  I may do something different with AL.  

The other joints in the trailer are perpendicular joints where I will drill   the larger tube and insert a smaller tube into the hole perpendicular to the   large tube.  I want the tubing to help me hold the welds in place since I am   a beginner and do not want to risk broken joints. 

This  is a low budget,  but quality oriented operation.  Our company doesn't want to go into debt, so I want the most cost effective way to make quality welds in both Chromolly and AL. If not possible, then I may use only AL since it is lighter, cheaper for materials, and easier on my equipment.  When you weld AL, is it a true weld or a solder/braze type weld?  Can you truly get nice looking welds with a Oxy/Acetylene torch?  The typical welders in our typical low tech community have never heard of welding AL with gas. Is there more information available to help me make my decision?     

I truly appreciate your feedback.  It has been hard to find suppliers who   are technically oriented and willing to help. Ray

The Tinman Respondeth:

Sheeeszh, Ray.   Drilling through for an axle is ok if: you machine a bushing to fit the hole, silverbraze it into place, and then run the axle through that.    Perp tubes do not do well inserted into a drilled hole for a joint because of distortion.

We use the fishmouth method, whereby the perp tube "mouths" onto the horiz. Snips, file, or bench grinder do the curved ends real quick. BTW, our video: Aircraft 4130 Chromemoly Airframe Construction covers this very type of construction perfectly, in 4hrs and 20 min. of detailed instruction. Aluminum may be gas welded.

See Booklets

It may also be soldered (650F) and brazed (800F), like heat exchangers, refrigeration, torque converters, etc.  It may be arc welded, MIGwelded, and TIG welded, too.    How pretty is an aluminum gas weld? Well, bub, I'll just have to digitize yesterday's work for you to peruse.

Kent

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