I'm considering purchasing a 5C collet chuck for my lathe. I'm
currently using 3 & 4 jaw chucks and want the added accuracy of 5C
collets. Having no experience with 5C collets, can someone tell me if
they will hold my work: I work a lot with bar stock in the range of
0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
is not production work - I can't build a specialized fixture or modify
a collet for each piece.

I plan to have 5C collets in 1/64" sizes for my OD range. Will
standard 5C collets hold my work for boring? What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet. I'd like to have some
sort of internal collet stop that still allows the 3/8" boring bar to
pass through the center. Any help is appreciated.

Regards,
Ed Ferguson

On 13 Oct 2003 11:56:37 -0700, (Ed) wrote:

I'm considering purchasing a 5C collet chuck for my lathe. I'm
currently using 3 & 4 jaw chucks and want the added accuracy of 5C
collets. Having no experience with 5C collets, can someone tell me if
they will hold my work: I work a lot with bar stock in the range of
0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
is not production work - I can't build a specialized fixture or modify
a collet for each piece.

I plan to have 5C collets in 1/64" sizes for my OD range. Will
standard 5C collets hold my work for boring? What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet. I'd like to have some
sort of internal collet stop that still allows the 3/8" boring bar to
pass through the center. Any help is appreciated.

Regards,
Ed Ferguson
Greetings Ed,
Collets will work in your application. Not only are adjustable stops
available but also spirin loaded stops. So these push the part out
when the collet is released. If the collet mounted stops won't work
because the part is too long then a stop which mounts in the spindle
tube or collet closer draw tube will work. If you are going to get
one of the closers that uses a key (like the Bison Brand) to close the
collet and the part is long then a stop that fits into the spindle
through hole will be the best option. Some are available in catalogs
but making one is simple. You can turn a piece of aluminum (or most
any metal you have lying about) to the size that fits your spindle
hole, at the rear, about .004" under, saw it in half at about 45
degrees, mill the sawn faces smooth, tap one of the halves and drill
the other. Then, screw a piece of all-thread through this piece so
that the end of the all-thread is where you want the part to bear with
the wedge shaped piece at the rear of the lathe. Slide the piece
without threads on the all-thread and use a nut to tighten the wedge
shaped pieces together. This will fix the stop in your lathe. On the
business end of the all thread you screw any shaped piece on you want
that will allow your tool to go completely through the part. An
advantage with this type of stop is that it is a "dead length" stop.
So as part diameter changes the part will always be stopped in the
same place. With a collet mounted stop as the diameter varies and the
clamping pressure varies the part length varies. This is because the
collet is drwan back into a taper to cause the collet to collapse
against the part being held. With a smaller part, or with higher
clamping pressure, the collet is drawn back farther into the taper.
There are closers that move the taper and the collet is stationary but
these are expensive. More convienient, but more expensive that the
Bison type closers that use a key are the lever actuated closers.
Cheers,
Eric R Snow,
E T Precision Machine

You can buy or make a collet stop that fits in the back and presets
the depth stock can be entered, and there is no doubt in my mind if
you have to through drill stock held in a collet that you could
fashion a hollow stemed stop for the collet to allow boring completely
though the stock. I say not a problem.

On 13 Oct 2003 11:56:37 -0700, (Ed) wrote:

===I'm considering purchasing a 5C collet chuck for my lathe. I'm
===currently using 3 & 4 jaw chucks and want the added accuracy of 5C
===collets. Having no experience with 5C collets, can someone tell me if
===they will hold my work: I work a lot with bar stock in the range of
===0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
===bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
===is not production work - I can't build a specialized fixture or modify
===a collet for each piece.
===
===I plan to have 5C collets in 1/64" sizes for my OD range. Will
===standard 5C collets hold my work for boring? What I mean is, I don't
===want to bore a step in the collets (I'm not doing production work) to
===hold the piece a fixed depth in the collet. I'd like to have some
===sort of internal collet stop that still allows the 3/8" boring bar to
===pass through the center. Any help is appreciated.
===
===Regards,
===Ed Ferguson

Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

"Ed" wrote in message
om...
I'm considering purchasing a 5C collet chuck for my lathe. I'm
currently using 3 & 4 jaw chucks and want the added accuracy of 5C
collets. Having no experience with 5C collets, can someone tell me if
they will hold my work:

Sure will. Probably better than a regular three-jaw chuck. Certainly as
good. I've yet to have work come out (if I tightened the collet, that is.)

I work a lot with bar stock in the range of
0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
is not production work - I can't build a specialized fixture or modify
a collet for each piece.

The collets will be much better than the chucks for that application.
You're doing stuff that approaches thin walls -- a regular three-jaw chuck
will certainly distort something with 1/16" walls. Collets won't do that.

I plan to have 5C collets in 1/64" sizes for my OD range. Will
standard 5C collets hold my work for boring?

Sure. If you look at the collets you'll see that the gap is slightly bigger
for the 1/8 increments, smaller for the 1/32, etc. At least with my collets
they are. The 1/8 multiples have about a 1/16 1/8" diameter range. But of
course, you don't get as good a holding all around as with the closest fit
to your work.

What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet. I'd like to have some
sort of internal collet stop that still allows the 3/8" boring bar to
pass through the center. Any help is appreciated.

Most modern 5C collets are threaded internally for an adjustable stop. The
stop however, would also block the boring bar. I've never seen the kind of
stop you're talking about. But it isn't that big a deal to make a tubular
stop that would allow the boring bar through -- however, if you think about
it, the stop's wall thickness would have to be no bigger than your boring
bar.
How about just using a regular adjustable stop and putting in a piece
of thin wall tubing to act as the spacer and still leave room for boring bar
to clear?

If you're thinkingin terms of one of the Bison 5C, spend the extra bucks for
the "adjust-throug" versions. The added accuracy and run-out reduction is
well worth the cost.

boris
--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bbeizer "at" sprintmail.com

------------------------------------------

"Eric R Snow" wrote in message
...
On 13 Oct 2003 11:56:37 -0700, (Ed) wrote:

snip . Some are available in catalogs
but making one is simple. You can turn a piece of aluminum (or most
any metal you have lying about) to the size that fits your spindle
hole, at the rear, about .004" under, saw it in half at about 45
degrees, mill the sawn faces smooth, snip Eric's excellent idea

Ed.
Ignore my stop idea. Use Eric/s, Much better idea. Gonna make one like
that, next time.

Boris

--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bbeizer "at" sprintmail.com

------------------------------------------

In article , Ed says...

What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet.

You still might want to investigate purchasing some pot
collets (with a pre-bored recess of a specific depth
in the face) for your work.

Another option would be to purchase a few brass collets
to bore out.

Pot collets are very nice to work with, especially for
an application like yours - facing or boring short
parts.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

(Ed) wrote in message . com...
I'm considering purchasing a 5C collet chuck for my lathe. I'm
currently using 3 & 4 jaw chucks and want the added accuracy of 5C
collets. Having no experience with 5C collets, can someone tell me if
they will hold my work: I work a lot with bar stock in the range of
0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
is not production work - I can't build a specialized fixture or modify
a collet for each piece.

I plan to have 5C collets in 1/64" sizes for my OD range. Will
standard 5C collets hold my work for boring? What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet. I'd like to have some
sort of internal collet stop that still allows the 3/8" boring bar to
pass through the center. Any help is appreciated.

Regards,
Ed Ferguson



If I understand your question, the solution is to buy a standard
Hardinge style collet stop (screws into back of collet) and make your
own stop rods which are hollow for boring bar clearance. Hardinge
uses 1/2-20 threaded stop rods so you'll need ones with a bigger head
on the "stop" end. Over the years I've had the same situation you're
in and accumulated a whole bunch of home-made stops of various end
diameters.

Here's a hint to same some machining...buy those cheapo adaptors used
to mount grinding wheels on motor shafts. Most have a 1/2-20 thread
with a hollow big end to slip over the motor shaft. A couple bucks or
so. Machine the big end to suit your job.

In article ,
Ed wrote:
I'm considering purchasing a 5C collet chuck for my lathe. I'm
currently using 3 & 4 jaw chucks and want the added accuracy of 5C
collets.

You'll get better concentricity with a drawbar through the
spindle, if your late is big enough. To use a drawbar for 5C collets,
you need at least a 1-3/8" bore through the spindle. Then you need a
closer nosepiece to fit your internal spindle taper. Once you have
that, and good quality collets, your concentricity is limited by:

1) The exiting taper in the spindle.

2) The accuracy of the closer nosepiece (Royal makes some
very nice ones.)

3) The accuracy of the actual collet.

You will also probably prefer the lever style closer mechanism
(often found on turret lathes), instead of the handwheel on the outboard
end of the spindle.

If you don't have the 1-3/8" spindle bore, you will have to use
something like the Bison collet chuck, which while good quality, is not
as convenient for quick part changes. You'll be stuck with having to
use a key like that for the 3-jaw chuck to tighten and loosen the
collets -- and to change collets.

If concentricity is important, with the collet chuck, you really
should spend the extra for the "adjust-tru" feature, which lets you tune
the centering of the collet chuck after mounting it on the spindle.

Having no experience with 5C collets, can someone tell me if
they will hold my work: I work a lot with bar stock in the range of
0.7" to 1" diameter, in pre-cut lengths of 0.120" to 0.5". I need to
bore these pre-drilled pieces to ID's ranging from 0.5" to 0.8". This
is not production work - I can't build a specialized fixture or modify
a collet for each piece.

The length to diameter ratio makes things a bit more difficult,
especially with some less than 1/8" in length, and perhaps 1" in
diameter. You could (as others have suggested) make special stops which
are tubular section to clear the boring bar and hold the workpiece in
the collet.

Note -- that if these workpieces were not already cut to length,
you would be better to work with bar stock through the collet (you can
pass up to 1" bar through the spindle and the collet and drawbar). then
you turn to diameter (if necessary), drill and bore, and part off just
outside the collet, then you loosen the collet and advance the bar far
enough so you can produce the next piece. For this kind of operation,
the lever style closer is particularly nice. But -- you haven't yet
said whether the lathe is big enough to allow this.

I plan to have 5C collets in 1/64" sizes for my OD range. Will
standard 5C collets hold my work for boring? What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet. I'd like to have some
sort of internal collet stop that still allows the 3/8" boring bar to
pass through the center. Any help is appreciated.

Aside from making a special tubular depth stop as others have
suggested, which is still some special work for each size of stock you
want to work with since you can't buy them, the alternative (also
mentioned by some) is the collets designed to be bored to the size you
need -- and this could include a step to hold the depth, and keep the
thin workpiece square to the axis of the lathe. These are not of a
hardened steel (like normal collets), but rather a mild steel -- or even
brass -- with three pins to hold the pre-slit jaws opened to normal
spacing while you're boring to size for the workpiece (and boring
clearance behind the stop to accommodate the boring bar). Once you have
it to shape, you remove the pins, and the collet will close down on your
workpiece as you draw it in. Your diameter range is 0.700: through
1.000" -- but in what size steps? If just a few, it would be worth
while to bore several collets to size for each project. Alternatives
would be to bore a series of steps so the collet can hold more than one
size (size steps not too close together), and use a second one for the
intermediate sizes.

Note that to hold a collet nosepiece, the spindle taper will
probably need to be a MT-4 or larger. Mine (a 12x24" Clausing) is
MT 4-1/2. If you have the 1-3/8" spindle bore, you probably also have a
spindle taper large enough to accept the nosepiece. And if you have a
Hardinge lathe, it probably has a spindle designed to accept 5C collets
*without* an adaptor nosepiece.

A companion to the nosepiece is a spindle thread or taper
protector which is also used to remove the nosepiece. *Don't* put the
nosepiece in without the protector in place, or you may have to do
things which would damage the nosepiece or the spindle nose itself to
remove it.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

jim rozen wrote:

In article , Ed says...

What I mean is, I don't
want to bore a step in the collets (I'm not doing production work) to
hold the piece a fixed depth in the collet.

You still might want to investigate purchasing some pot
collets (with a pre-bored recess of a specific depth
in the face) for your work.

Another option would be to purchase a few brass collets
to bore out.

Pot collets are very nice to work with, especially for
an application like yours - facing or boring short
parts.

Jim


I was wondering when someone would get around to that. Get some brass or
steel emergency collets and machine to what you need. You can relieve what
you need for thru tools and you can take them out & put in later and have
everything as near perfect as you will need. Fiddling around with a bunch of
stops is bull****, a PITA. Using emergency collets for the sizes you are
doing, you'll be able to change to a different diameter piece in the time it
takes to remove and replace the collet. Unless of course, you want to fiddle
around with different stops that often are tuff to get a part to be in
squarely. Do yourself a favor, make it easy to make good parts. Cheaping out
on tooling and Mickey-Mousing are a waste of time. And I don't necessarily
mean dollar cost.

michael

In article , DoN. Nichols says...

...the alternative (also
mentioned by some) is the collets designed to be bored to the size you
need -- and this could include a step to hold the depth, and keep the
thin workpiece square to the axis of the lathe. These are not of a
hardened steel (like normal collets), but rather a mild steel -- or even
brass -- with three pins to hold the pre-slit jaws opened to normal
spacing while you're boring to size for the workpiece (and boring
clearance behind the stop to accommodate the boring bar). Once you have
it to shape, you remove the pins, and the collet will close down on your
workpiece as you draw it in. Your diameter range is 0.700: through
1.000" -- but in what size steps? If just a few, it would be worth
while to bore several collets to size for each project. Alternatives
would be to bore a series of steps so the collet can hold more than one
size (size steps not too close together), and use a second one for the
intermediate sizes.


There are indeed a variety of ways to skin this cat.

A brass or nylon emergency collet can be bored to size,
they also make soft steel ones.

But I've got a large number of regular hardinge collets
that a tooling shop transformed into pot collets, by
boring them out, presumably with carbide tooling. These
were with very short (1/8 deep) recesses, but they could
have been done deeper.

For larger diameter sizes there are step chucks made
with the pins, which are also bored to size. Those
are typically semi-steel.

If the original poster has a lathe smaller than 5C,
I would mention that I also have a large number of
very small diameter 3C collets, that the same manufacturer
had used as the starting point for some 3C pot collets.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================