Model Forum / Radio Controlled / Land Models / July 2004

My project truck has just hit its first stumbling block.  The rear dogbone I
was planning to reuse in the transmission has just been extracted from the
rear suspension and is bent.  The other one is broken (prompting me starting
the project earlier than planned).  The bend is very near the ball end and
is not major (about 20 degrees at a guess) but will be enough to vibrate the
truck to death when migrated from the drive shaft (about 2,500 rpm) to the
transmission (about 11,500 rpm).  I know these shafts are hardened steel so
my question is:  Can I, as a hobbyist engineer, recondition this drive shaft
with the normal household and hobbyist tools?

My thinking at the moment is to put the main shaft in a vice, heat the bent
shaft in a gas hob flame and grasp with a pair of pliers and bend back to
straight.  I have nothing to lose by trying it as I shall throw this dogbone
away if I have to buy a replacement.

There are a couple of things I don't know.  Can I get enough heat out of a
gas hob flame to get the shaft to a temperature where I will be able to bend
it straight?  Are there visual clues as to when I have hit the right
temperature (e.g. orange hot, red hot etc) because the last thing I want to
do is melt the shaft properly!

Now, from my vague recollections of metallurgy I can reharden the steel by
heating it up (as above) and letting it cool naturally.  Is this the right
way round?  Should I cool it quickly instead?

Thanks in advance for your help,
Bobby