[TheForge] Re: Welding cast iron

[Mike Spencer]

pf wrote:

> A related approach is to cast a screw in graphite compound or
> refractory and build up a nut with brazing...chip out the screw core
> after it cools.  Want another dozen impractical solutions?...pf

Well, if we're looking at esoteric solutions....

I had a screw in good condition and a couple of polished tubes
suitable for guide bars and wanted to make a wood vise.  I had some
1/8" square stock (shipped by mistake years ago) so I wrapped it into
the groove of the screw, heating with a torch as I went. Cooled,
removed, inserted the little helix into a piece of tubing.  Heated the
whole thing and flowed brass into it, brazing the helix into the tube.
Had to clean out some of the excess brass with a tiny wheel and a die
grinder.  Then lapped the male threaded part into the new part with
lapping compound.  Presto, a threaded collar to go in a wooden vise
jaw. 

One point to note when doing this: If you wrap square stock tightly
like that, the stock gets thicker on the inside and thinner on the
outside of the curve, just as it does in any bend. So to make a square
thread (as opposed to Acme thread that is sort of truncated-pyramid in
cross section) I had to draw-file the stock to make it a kind of
isosceles trapezoid in cross section over the length I was planning to
use, then wrap it with the narrow face toward the mandrel.  That made
it come close enough to square-thread after it was wrapped.

Years ago, Dimitri Gerakaris showed me a leg vise he had fixed in a
similar way.  Some years after that, he somewhat sheepishly reported
that it hadn't worked out in the long run.  I imagine it just wasn't
strong enough to have a hefty guy like Dimitri huffing for all he's
worth on a long vise handle. :-)


FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^