I'm working from the pdf files of articles written by Exactus:
As you suggested, he has you make the collets in pairs and gives the
order of most of the machining operations as well as methods (which
us newbies wouldn't think of) to improve the accuracy of the result.
His articles are general in that they aren't about 3C collets, just
collets in general.
I would like specs on 3C collets if you can find them, especially the
angle of the steep taper. I calculated it as 11 degrees but it
didn't seem to fit properly so I used 12 degrees. The expanded
nature of my brass collet makes it difficult to evaluate the fit
using chalk or machinist blue because once the collet is in the chuck
it is hard to rotate it while it is tight against the taper.
My conclusion about the hardness of the shock absorber rod is based
on my hacksaw/Sawzall test; I couldn't cut it to fit into the lathe
until it was annealed. I don't have a steadyrest (yet).
Once it is in the lathe I start at the end adjacent to the live
center and make a truing cut which takes the chrome (green after
annealing) off using a carbide tool. Seems to work OK although it
smokes a bit as the cutting oil burns off the chips.
John
--- In 7x12minilathe@..., William A Williams
<bwmsbldr@j...> wrote:
Thanks for the information. Somewhere I have seen a
dimensioned drawing
of a 3-C collet; if I find it I will get it to you. I suspect that
you
are "skating" the tool tip on the chrome plate. You have to cut it
off
with a shouldering tool or one that actually undercuts the plating.
You do know to make the collets in pairs? I think that I have
the
procedure for turning them spelled out in an old English machining
book.
Bill in Boulder "Engineering as an Art Form!"
