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?
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?
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?
>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
>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
>>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
> 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.
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...
>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?
> 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.
> 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
