Gunner Asch on Sat, 12 Jun 2010 00:38:39 -0700
typed in rec.crafts.metalworking the following:
On Wed, 09 Jun 2010 11:45:27 -0700, pyotr filipivich
wrote:

Gunner Asch on Wed, 09 Jun 2010 01:24:41 -0700
typed in rec.crafts.metalworking the following:
On Tue, 8 Jun 2010 18:13:30 -0700 (PDT), Searcher7
wrote:

I entertained the idea of filling out the rest of my set of 5C collets
several years ago. Now I'm thinking about it again, but there is a
possible issue which I didn't really consider originally.

[snip]

Unfortunately...far far too many importe (Asian) collets are under or
over sized. A 5C collet has at most..a .015 grip range..and most of them
are .006. Ive seen far too many of them that were in that 15 thou
range..but a .500 collet may open to .485, and close to .497....which
really doesnt help much when your stock is .502 +/- .004

Hardinge, Lyndex, Royal, etc etc and several other german or polish made
brands are Good stuff.

Another issue..is that not all collets have the holes drilled in the
middle G

When you have a spindle nose thats dead nuts...000000+/-
and you put in a gauge pin..and the runout is .004....that means
something is not right. If it were .0001..its still not right.

Some of the imports are pretty good. Some are pretty bad. The biggest
problem with a lot of the collet sets..is that you have a mix of good
and bad ones. And if you dont select the good one..when you turn
it..things dont come out the right size.

So, best bet is in your copious spare time, go through all the
collets, and find out what size they "really" are, as well as how true
they might be?
I wonder how one might "true up" a collet. It would also depend
on whether the bore is undersized _and_ off center. Boring an
undersized one might be a challenge - I keep thinking of honing one
"out" to proper size, and possibly even to dead nuts centered, But
that would take some know how as well as time and equipment.

My opinion, and worth exactly what you paid for it..is to buy known
brands of Good collets and not bother with Chicom imports. Even used
collets will likely still be on the money. In fact..Ive only bought (1)
new collet, because I couldnt find a hex collet in 7/8s, used, anywhere.

And it was a Hardinge.

Collets( good ones) are hard as a whores heart. The only way you are
going to get an undersized one cleaned up to the proper size..is to
grind it to size. It can be done..but shrug...it depends on what you
are actually needing it for.

The consensus seems to be, out of round collets get dumped,
undersized get remarked. Unless one wants to spend the time and
effort to hone one out to size ... it isn't worth it.

Sort of like making your own mill from scratch - starting from the
casting of the big iron bits. Yes, it can be done, but why???
--
pyotr filipivich
We will drink no whiskey before its nine.
It's eight fifty eight. Close enough!