On Jun 19, 3:13*pm, Jim Wilkins wrote:
On Jun 19, 11:25*am, Searcher7 wrote:



On Jun 17, 7:43*am, Jim Wilkins wrote:
On Jun 17, 1:46*am, Searcher7 wrote:
On Jun 16, 6:53 pm, "DoN. Nichols" wrote:
...

Now this is what's been bugging me. 3C will fit into my MT3 lathe
spindle, and MT3 collets will fit into my MT3 lathe spindle, correct

The 3Cs at LMS go as high as 1/2" and only allow a diameter as high
as .467 through the collet.(The site doesn't mention these specifics
for MT3 collets).

If you can pass the rod stock through the spindle you can machine a
part on the end with access to its entire length. Otherwise you have
to plan how to machine the area clamped within the collet or chuck
jaws in a second operation with less centering accuracy, or waste some
material, or hold it between centers. The difference is mostly
convenience and forethought.

?!?

It sounds like you're just saying that when passing the stock through
the spindle, a longer length of stock can be machined without un-
clamping. (Which is the same as saying to just use longer stock).
Darren Harris

No. Deflection controls the maximum length you can have protruding
from the chuck or collet. The part inside the spindle is irrelevant.

I thought that the distance between tailstock and headstock would
determine this. And I assume deflection is why steady rests were made.

What I intended to convey is that you can make a 1" part on the end of
a 36" rod and not waste any material. When you are done you still have
35" of good stock left (ignoring the cutoff bit). If you started with
a 2" blank, the half clamped in the chuck or collet would be wasted.
But you might have to if the full-length bar won't fit through the
spindle.

If the stock is too large to go through the spindle I cut off either a
6" piece to stick in the chuck or a 24" piece to turn with a steady
rest, even to make a 1" part. Then I still have a useful length left
over for the next part.

It may not be 6", rather the maximum length of that diameter that will
be stiff enough to cut. If I guess wrong I support it with the
tailstock center. When it's used up there is only one short scrap
piece, which may become a bushing.

What I DON'T want to do is turn my leftover stock into short useless
chunks cut off the ends of the parts I made.

^^^^ This is what passing the stock through the spindle is all about.

Yes. My determination is that with my lathe 9/16" would be the maximum
diameter I could pass through the spindle using 3C collets, because
that is the largest diameter these collets are made for.

Higher than that would require a 5C collet chuck for the 5C collets.

It also helps if you are making bicycle spokes or threading the ends
of tubing, long thin parts machined on both ends, but you can do them
between centers or with a steady rest if necessary. A long thin rod
protruding out the left end of the spindle will bend and whip around
unless you support it somehow.

Of course. But I have no projects like that on the horizon yet.

You need more experience and less speculation, Aristotle. Use your 3
and 4 jaw chucks, they are the basic work holders, collets are a
luxury. I've brought them up to consider BEFORE buying a lathe. They
aren't worth a lot of fiddling to cobble on inaccurately afterwards.
In your case I would buy the 3C set and if needed, larger sizes in
MT3. You'll never find an elegant, complete and perfect solution to
everything (though 5C is close) and have to learn to adapt what you
have somehow, or bid the job out.

MT3 collets use a drawbar, so they are not an option.

(Now to look into a lathe modification involving adding a 5C
spindle). :-)

Darren Harris
Staten Island, New York.