Nolan Penney wrote:
> A torch is much slower at melting the metal, resulting in
> greater heat saturation, and the warping that results from
> this. Things like wet rags rolled up around the weld site
> help, but are no guarantee.
There are products you can use that help even more, although
distortion is still a problem.
I use the stuff with great success, it's like runny blue
play-dough. One brand name is Sta-Frost putty, although I
am not sure what brand name I have it was bought from a
welding shop and came in a plain can.
It's rather expensive ($20/pound) but it's reusable a few
times and it really works well. Essential for welding near
rubber seals you don't want to remove, glass, and so on.
I just recently used it to weld seatbelt upper mounts
onto a B pillar without wrinkling any fresh paint
on the outside.
> Btw, do not be afraid of rivets. Yes, they get a bad rap, but
> that's because most people do them very poorly. They go to a hardware
> store and buy junk pop rivets, and don't use them correctly. Quality
> rivets, installed correctly, are extremely strong. Stronger
> in fact then welding.
I would VERY much disagree that rivets are stronger than welding. In
fact, stronger than welding is not really a possible goal, because
a proper weld seam is as strong as if the seam never existed, so if
the seam is stronger than the surrounding metal, then you'll just
tear the surrounding metal.
However, more important than all of this, you can't use aluminum
rivets in a steel body. The dissimilar metals will cause very
rapid corrosion. Even if the corrosion isn't a visual or structural
problem, the metal will rust away and the rivet will quickly
become loose in it's hole.
Airframes are indeed rivetted, but these are alumimum frames held
with aluminum rivets so corrosion is not an issue. The other uses
for rivets in construction have a lot more to do with speed of install
and the reliability of inspection: It's a lot easier to inspect
a 10 foot rivetted seam on a 24 gauge alumimum aviation body every
two years than to inspect the same length of weld! Plus, any loose
rivets can be installed and reinspected in situ without recoating
should failures be found or a section needs to be replaced.
As far as I know, Steel rivets are either not available or
not practical because they take specialist tools to install.
--
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/
Live From Tapwater Springs.
|