I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.

20 thou is a lot. I'd seriously consider getting a new one. For
years I fought a 6" 3 jaw chuck that was about 6 thou out. I tried a
couple of the solutions that you no doubt will get from this post, but
they didn't work for me.
Finally, about 6 or 7 years ago I bought a brand new set-true chuck.
Even though it cost me $350 (3 times what I paid for the whole
(used)lathe 30 years ago, it was and is still worth it.
It has 0.0004" run out. I can simply throw stuff in there and cut
metal.
You may not need a 7 or 8 inch chuck. consider a 6" to hold the
cost down.

You may be right about hurting the jaws with a drill or end mill.
I'd also suggest getting a collet or two for holding them. End mills in
particular seem to pull out of the 3 jaw chuck.


Pete Stanaitis
------------------------------------
Den wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.

spaco wrote:
20 thou is a lot. I'd seriously consider getting a new one. For
years I fought a 6" 3 jaw chuck that was about 6 thou out. I tried a
couple of the solutions that you no doubt will get from this post, but
they didn't work for me.
Finally, about 6 or 7 years ago I bought a brand new set-true chuck.
Even though it cost me $350 (3 times what I paid for the whole
(used)lathe 30 years ago, it was and is still worth it.
It has 0.0004" run out. I can simply throw stuff in there and cut
metal.
You may not need a 7 or 8 inch chuck. consider a 6" to hold the cost
down.

You may be right about hurting the jaws with a drill or end mill. I'd
also suggest getting a collet or two for holding them. End mills in
particular seem to pull out of the 3 jaw chuck.


Pete Stanaitis

Agree I do 90, no 95% of the stuff I do on a 6" 6 jaw set true on
a 13" lathe.




------------------------------------
Den wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it
is a off centre by ~0.020". Looking at the jaws I can see where they
are flogged out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and
clamp some work in a vertical mounted vice on the cross slide. I dont
know if gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow
external/outside edge clamping - can I wind the jaws out and fit a
ring and then run a boring bar across the inside clamping surfaces of
the jaws as someone here mentioned a week or so back?

Cheers.

On Thu, 24 Jul 2008 07:32:25 -0500, spaco
wrote:

20 thou is a lot. I'd seriously consider getting a new one. For
years I fought a 6" 3 jaw chuck that was about 6 thou out. I tried a
couple of the solutions that you no doubt will get from this post, but
they didn't work for me.
Finally, about 6 or 7 years ago I bought a brand new set-true chuck.
Even though it cost me $350 (3 times what I paid for the whole
(used)lathe 30 years ago, it was and is still worth it.
It has 0.0004" run out. I can simply throw stuff in there and cut
metal.
You may not need a 7 or 8 inch chuck. consider a 6" to hold the
cost down.

You may be right about hurting the jaws with a drill or end mill.
I'd also suggest getting a collet or two for holding them. End mills in
particular seem to pull out of the 3 jaw chuck.


Pete Stanaitis
------------------------------------
Den wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.



Den
I would recommend you making a trip over to HAFCO in Belmont and
buying a new chuck. Fuerda chucks are not expensive. They also have a
polish made chuck that is quite reasonable.
Google for Hare and Forbes or HAFCO on australian only pages, they
have a website with online cattledog.

(I bought 2 new ones for a Myford I'm restoring. they're not
expensive)
Stealth Pilot

On Thu, 24 Jul 2008 20:00:26 +0800, "Den"
wrote:

I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.


Greetings Den,
First take apart and thoroughly clean then lube and reassmble the
chuck. Make sure then scroll is clean and the scroll sectors in the
jaws are clean. To fix the inside jaws you will need to grip a spider
that loads the jaws the same way as gripping a part on the OD. If the
jaws are one piece then the only place you can really grip a spider is
at the bottom of the jaws. Once the jaws are closed on the spider with
normal clamping force the jaws can be ground. For the outside of the
jaws use a ring and expand the jaws against the ring. Now the jaws
will run true but only in the places where they were ground. Runout in
other positions may or may not run true depending on the wear.
Cheers,
Eric

We have several Bison (Poland) 6- jaw set-tru chucks that are great

one of them saw daily production in a cnc lathe for years, you can't tell it
from new.

Parts are available for the occasional oops.

=)

I got mine at MSC


"Stealth Pilot" wrote in message
...
On Thu, 24 Jul 2008 07:32:25 -0500, spaco
wrote:

20 thou is a lot. I'd seriously consider getting a new one. For
years I fought a 6" 3 jaw chuck that was about 6 thou out. I tried a
couple of the solutions that you no doubt will get from this post, but
they didn't work for me.
Finally, about 6 or 7 years ago I bought a brand new set-true chuck.
Even though it cost me $350 (3 times what I paid for the whole
(used)lathe 30 years ago, it was and is still worth it.
It has 0.0004" run out. I can simply throw stuff in there and cut
metal.
You may not need a 7 or 8 inch chuck. consider a 6" to hold the
cost down.

You may be right about hurting the jaws with a drill or end mill.
I'd also suggest getting a collet or two for holding them. End mills in
particular seem to pull out of the 3 jaw chuck.


Pete Stanaitis
------------------------------------
Den wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it
is a
off centre by ~0.020". Looking at the jaws I can see where they are
flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and
clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow
external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a
boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.



Den
I would recommend you making a trip over to HAFCO in Belmont and
buying a new chuck. Fuerda chucks are not expensive. They also have a
polish made chuck that is quite reasonable.
Google for Hare and Forbes or HAFCO on australian only pages, they
have a website with online cattledog.

(I bought 2 new ones for a Myford I'm restoring. they're not
expensive)
Stealth Pilot

On Jul 24, 6:00*am, "Den" wrote:
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn *and when small diameter work is fitted it is a
off centre by ~0.020". Looking at the jaws I can see where they are flogged
out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.

I did this, once, cleaned out the crud in the scroll, relubed, then
made a ring and and a cross-slide rig for a die grinder to grind out
the divots in the jaws. If you do this, you can get it pretty good,
at that one spot. If you've got hardened jaws, some form of grinding
may be your only way of cleaning up the faces.

Best bet is to learn how to use a 4-jaw chuck, 99% of what I do is
done with a 4-jaw. It's only when I need to chuck up hex stock that
the 3-jaw gets put back on the machine. It really doesn't take that
long to chuck up something to within a half-thou using a good
indicator.

Stan

Most chucks come with hardened jaws and grinding jaws is a bitch, even after
you dissassemble the chuck, clean it all as best you can, reassemble it,
your grinding job will only be as good as your (probably well used) scroll
is, and I it's STILL going to come out bell mouthed.

As has been suggested, turn this into a paper weight and buy a new chuck.
Honestly 10 years ago my neighbor tried to fix a skanked out old 3 jaw,
after a weeks worth of work (and grinding dust all over his lathe) it was
still crap. I convinced him to buy a Bison from ENCO and he's been a happy
camper ever since. FWIW he made his own "tru-set" back for it... it's not
that hard to do, he just used an overside backing plate, turned down an
inner area for the chuck and drilled and tapped 4 #6 set screws in edge that
was left to push the chuck around.. I though it was a clever idea.

Since everyone is bragging about how they do %90 of their work I'll weigh in
on that to.

Back when I had my import lathe I got a chuck style collet closer for it,
it wouldn't mount any other kind of thru the spindle closer. Best thing I
ever did.

When I got the 5914, first thing I did was mount a Royal lever action closer
on it... I do %99 of my work with the full set of 5C's I have.. even square
and hex... Once you get a lever action closer you'll wonder how you ever
survived without one..

I brake out the genuine 8 inch Buck tru-adjust 3 jaw if I need something
bigger than 1 inch... and if I need the accuracy down to .0005 I can adjust
it.

I use my 8 inch Southbend 4 jaw for eccentric work.

Once in a blue moon I put on the 12 inch face plate for something really big
and wierd.

I'd NEVER... EVER.... grab an end mill or drill bit in a 3 jaw, you are
asking for trouble... no matter how good you think your jaws are they are no
where near parallel when it comes to grabbing a hardened tool shank... I
wouldn't think twice about sticking one in a 5C though...

--.- Dave


"Den" wrote in message
...
I looking for some advice on how to improve my lathes 3 jaw chuck.

Without going out to the workshop to measure it, it's about 7" or 8"
diameter. The jaws are worn and when small diameter work is fitted it is
a off centre by ~0.020". Looking at the jaws I can see where they are
flogged out a little, particulary the outermost 10mm or so.

I occaisionally stick a drill bit or endmill cutter in the chuck and clamp
some work in a vertical mounted vice on the cross slide. I dont know if
gripping the hardened tools has contributed to the jaw wear.

What's the best way to clean them up. The chuck jaws allow
external/outside edge clamping - can I wind the jaws out and fit a ring
and then run a boring bar across the inside clamping surfaces of the jaws
as someone here mentioned a week or so back?

Cheers.

What's the best way to clean them up. The chuck jaws allow external/outside
edge clamping - can I wind the jaws out and fit a ring and then run a boring
bar across the inside clamping surfaces of the jaws as someone here
mentioned a week or so back?

Cheers.

Den

I had a new chuck that was way out also. I took it apart, cleaned and
lubed everything and no change. Then on a whim I rotated the jaws one
position away. Bing. Right on. Now I have the jaws marked as to which
slot for each one is correct. Or as I expect that many do, get a
supply of shim stuck.

Re the ring thing. The jaws will set differently using a ring as you
indicate. You need to clamp the jaws in a ring and wind them in as you
say. Then grind the divots as one said. If the jaws are shaped such
that a ring will hold them then the clamping thing will not be
necessary.

Bob AZ

Den
I would recommend you making a trip over to HAFCO in Belmont and
buying a new chuck. Fuerda chucks are not expensive. They also have a
polish made chuck that is quite reasonable.
Google for Hare and Forbes or HAFCO on australian only pages, they
have a website with online cattledog.

(I bought 2 new ones for a Myford I'm restoring. they're not
expensive)
Stealth Pilot



I might have to go that way. I have a H & F catalog somewhere..... I might
drop into Fiora too next time I'm out that way and see what they have.
Cheers