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Pherdie
05-14-2009, 08:43 AM
Probably one of my better metal working purchases was to deep six my Chinese (Jet) 3 jaw chuck and go to a Bison Tru-Set with reversible jaws. Over the years the chuck has preformed flawlessly.....until the other day.

After a number of different operations (and LOTS of chips) it began to take a significant amount of elbow grease to open and close the jaws. Since I hadn't disassembled and cleaned the chuck since new, it was overdue for a tear down and cleaning. Once apart, and the chuck body cleaned, I tried inserting and sliding the jaws independently in their slots to make sure they rode freely and were not binding. Although the #1 jaw was fine, the #2 jaw was binding and the #3 was worse yet. The #1 jaw rode fine in the #2 and #3 slots. The converse was not true.

Everything appeared to be OK and devoid of any chips. I began to become concerned that somehow the chuck body had warped, but caliper and micrometer readings showed all three slot bearing surfaces with identical measurements and square surfaces.

Since the problem appeared to travel with the jaws, I removed the reversible portion of the jaw from the #2 jaw and then reinserted the lower portion of the jaw back into it's appropriate slot. VOILA!!! It slid perfectly. Same for the #3 jaw once the upper portion was removed.
Apparently, both the #2 and #3 jaws had sufficient foreign material between the upper and lower halves so that once tightened, they would twist and bind in their slots. Once the jaw segments were cleaned, reassembled and retightened, everything worked perfectly.

I had been so sure that chips in the scroll assembly were my culprit, but I found out a little more thought may be necessary in tight tolerance devices. I might also add that I never use compressed air to "clean" my equipment, opting for an oft used chip brush.

Hopefully sharing my experience will help others along the way.

Fred

andy_b
05-14-2009, 09:09 AM
i recently cleaned the 3-jaw chuck on my lathe and there must have been two pounds of chips in it. it works much nicer now. :)

so how does a person keep the chips out? i had been machining a bunch of tubing IDs, and the chips would fall out the back of the tube and into the chuck. i'm not sure how you could stop this.

andy b.

JCHannum
05-14-2009, 09:27 AM
Boring will introduce chips into the chuck and spindle bore more than OD turning. If I remember, I will stuff a rag into the spindle to keep chips out when boring. I mentioned in a previous post that I have used RTV to fill the void between the chuck body and backplate to exclude chips.

Both of these help exclude chips, but a chuck should be dismantled and cleaned on some regular basis. It is the nature of the beast, chips will get in there and cause binding and wear.

Ron of Va
05-14-2009, 09:33 AM
I have the Grizzly G4003G. I tried to disassemble the chuck a month or so ago to clean it. I got the jaws off, I removed all the screws, but I couldnít get to the scroll. I couldnít even see a seam where the thing went together.

I tried for over an hour to get it apart or even locate the seam. I never did get it apart.:mad: I cleaned it the best I could but was never really satisfied.

Maybe they were made by the same Chinese company. How did you finally get to the scroll?

JCHannum
05-14-2009, 09:40 AM
Almost all three jaw chuck bodies separate at the centerline of the pinion bore. Usually tapping, or use of a thin wedge will separate them.

Also, backing the body bolts out slightly and tapping them will usually start the chuck to separate.

Ron of Va
05-14-2009, 09:50 AM
Almost all three jaw chuck bodies separate at the centerline of the pinion bore. Usually tapping, or use of a thin wedge will separate them.

Also, backing the body bolts out slightly and tapping them will usually start the chuck to separate.

I tried tapping the bolts. It didn't work. Maybe I didnít hit them hard enough. I was afraid to get to aggressive and damage the threads. I even laid a block of oak across all the bolts and gave it some serious whacks and the seam didnít even appear.

I started to remove the bolts, then tighten the jaws down on my slide hammer, and give it a whack, but I was afraid the shock would crack the scroll with all the pressure on the jaws during the impact.

I will give the bolt tapping thing another try. Thanks

Pherdie
05-14-2009, 09:59 AM
I have found some chucks have specially provided threaded holes in the rear dedicated to facilitating splitting the chuck halves. Threading bolts in will push the two halves apart. Use equal threading to avoid cocking the halves.

Ron of Va
05-14-2009, 01:42 PM
I have found some chucks have specially provided threaded holes in the rear dedicated to facilitating splitting the chuck halves. Threading bolts in will push the two halves apart. Use equal threading to avoid cocking the halves.

My chuck doesn't have any such holes. Sounds like a good idea. I remember looking for such a method. I even thought the cam locking bolts on the D1-5 mount were to act as such a pressing force, so I tightened them up to see if that would work. But no.

demerrill
05-14-2009, 04:53 PM
Why not give Grizzly customer support a call ?
http://www.grizzly.com/q_and_a.aspx

Or post a query on the benchrest gunsmith's forum where many own a G4003G and the owner of Grizzly (an avid target shooter) monitors and sometimes participates ?
http://www.benchrest.com/forums/forumdisplay.php?f=17

Let us know what you find out.

David Merrill (another new G4003G owner)

Ron of Va
05-14-2009, 06:38 PM
Why not give Grizzly customer support a call ?
http://www.grizzly.com/q_and_a.aspx

Or post a query on the benchrest gunsmith's forum where many own a G4003G and the owner of Grizzly (an avid target shooter) monitors and sometimes participates ?
http://www.benchrest.com/forums/forumdisplay.php?f=17

Let us know what you find out.

David Merrill (another new G4003G owner)
I will give Grizzly a call and try their advice. Then I will report back. I thought the bolt tapping was the way to do it. Mine is probably just stuck. (it won't be the first time I have destroyed something taking it apart, :D )

Ron of Va
05-15-2009, 04:35 PM
I called Grizzly and talked with one of their technicians. He didnít know how the chuck comes apart, and then he put me on hold to ask someone else. He came back on the phone and said that the chuck is not designed to come apart, and if I take it apart it will void the machineís warranty. Yep, he said the machineís warranty, but I was too shocked about the chuck, his words about the machine didnít register until I had hung up.

I told him that it was crazy the chuck wonít come apart for cleaning, and it is recommended by most chuck manufacturers that the chuck be cleaned a couple of times a year. He insisted I should not disassemble the chuck.

I asked to speak to someone else. He said someone else would call me back. So far no return phone call.