Michael Horowitz wrote in
:

On Wed, 19 Sep 2007 17:23:13 +0000 (UTC), Fortunat1 wrote:


While we're on the subject, I have a question about Rosette welds.
With the specified hole size in realtion to the thickness of the
metal, I have a hard time getting the metal underneath to heat up
enough to melt before I blow away the metal on top. I have preheated
the innner piece as much as possible and this does produce better
results, but It's still a bit hit and miss. Is there a trick? Smaller
tip? Bigger?

This is first cousin to the posting I just made concerning welding an
inner sleeve. Unfortunately, the solution is probably different.

What I was shown was to drill an 1/8" hole in the top layer, aim the
flame at the inner piece and let the 1/8" hole melt back. by the time
the hole increases to 1/4", the inner piece will have formed a
puddle. Give her a try on some scrap; I tried it with two pieces of
sheetmetal and it worked. - Mike



Yes, I've tried a few pieces and had mixed results. You've certainly
answered one question that was banging around in my head and that was "can
you allow the hole on the top piece to expand?" Apparently you can.
A bigger problem for me is one of the parts I have to make is a compression
tube with a solid plug in the end. Actually Ii have to make 12 of them. The
plans call for fixing this plug in the tube end (3/4 .035 tube) with a pair
of rosettes. I've tried this and actually found it easier than the blind
plug thing by heating the plug where it's exposed and then zapping in the
rosette while it's hot. I'm finding the blind rosettes a lot more difficult
but I don't seem to be doing anything too wrong so it muct just come down
to practice!