Chuck Jaws

Discussion in 'Newbie' started by Dave Fritz, Dec 22, 2016.

  1. Dave Fritz

    Dave Fritz

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    My VM100 35mm jaws recently became sloppy and when I tried to tighten the screw it was stuck to the jaws. So much so that after spraying with WD-40 it came loose but it turned with the screw still attached to the jaw so the jaw and screw came out of the chuck as one. In doing that I nicked up the raised arch on the jaw that fits into the corresponding grove on the chuck body. After using a triangle file I was able to get the jaw to seat properly and able to put the screw back in.

    My question - what maintenance do you routinely do so something like this doesn't happen? I will add, these jaws are pretty much dedicated to that chuck so I rarely change them.
     
  2. A light coat of Permatex Anti-Seize Lubricant (item #81343) on screw threads and other mating surfaces when assembling jaws to the chuck body will do the trick. Available at auto supply stores. - John
     
  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    None. Other than to blow it out with an air gun every year or so.
    My Vic 120 is only 12 years old.
     
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  4. odie

    odie

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    I do the same......blow out the chuck after nearly every use.

    I did once, have to disassemble my Oneway Stronghold chuck, when the jaws became too difficult to open and close. I use a lubricant when it becomes very sticky. I've since decided any lubricant will attract sanding dust, and become an internal "sludge", which eventually further exacerbates the problem. When the jaws become sticky, I still will use a lubricant out of necessity.....but very sparingly. Then the jaws are opened and closed fully several times to spread it throughout. Eventually, I know I'll have to disassemble the chuck again.....it's a necessary evil to add lubricant.
     
  5. odie

    odie

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    I do the same......blow out the chuck after nearly every use.

    I did once, have to disassemble my Oneway Stronghold chuck, when the jaws became too difficult to open and close. I use a lubricant when it becomes very sticky. I've since decided any lubricant will attract sanding dust, and become an internal "sludge", which eventually further exacerbates the problem. When the jaws become sticky, I still will use a lubricant out of necessity.....but very sparingly. Then the jaws are opened and closed fully several times to spread it throughout. Eventually, I know I'll have to disassemble the chuck again.....it's a necessary evil to add lubricant.
     
  6. Dave Fritz

    Dave Fritz

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    Looks like you did it twice Odie. :)
     
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  7. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I don't blow mine out twice with each use :D, but I do frequently blow the dust out usually at the end of a day of turning. I have Oneway and Vicmarc chucks and never had any problems other than turning a bit too close on a couple occasions and discovering that you can actually turn the jaws with no ill effect on the turning tool.

    The angle of the conical recess for the screw head on the jaws is intentionally slightly steeper than the angle of the flat head cap screw in order to create a positive lock for the screw. You have noticed that when removing the screw that there is a snap release of the screw which is evidence to that locking action. My advice is don't over-torque the screws when tightening them because that can make them especially hard to remove. All that is necessary is to use a flick of the wrist, but most definitely not a white knuckle tightening.

    Slightly off topic is that I have seem turners overdo it when screwing the chuck onto the spindle and then wonder why it is so hard to remove it. Some turners use a slight flick of the wrist to "seat" the chuck, bit I feel like even that small extra bit of torque is usually more than what's needed. I now just screw the chuck onto the spindle until it seats and that is more than enough to keep the chuck from unscrewing when running the lathe in reverse for sanding.
     
  8. Michael Mills

    Michael Mills

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    1+ on John's suggestion of an anti-seize on the chuck jaw screw threads. AutoZone has little packets (very very little packets) for about a buck or you can get about 6 oz back in the oil section for about $5.
    Instead of any oil or grease I disassemble and clean well. I use aerosol graphite to coat all moving parts. The carrier flashes off in about a minute and leaves a completely dry surface that does not attract or hold dust. I usually give them two coats prior to reassembly. I may blow out the backs of my open chucks about once a year whether they need it or not. On my closed back I have never taken them apart again and never had a problem.
     
  9. john lucas

    john lucas

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    Ditto on the dry lube for the gears inside the chuck. My Vicmarc's are well over 12 years old. At least one of them. The other 2 might be 10 or less. Anti seize is the way to go for the allen screws. It only takes a teensy tiny bit. That stuff will be on everything in your shop in 10 minutes if you use much. I also never tighten the screws much, just enough to snug them down. I almost stripped the allen head on one many years ago from over tightening. If you do feel the Allen slip sharpen the tip of it to make it bite better.
    On tightening the chuck. I learned to put it on hand tight and take the chuck tightening wrench and give it a little push to add that little extra. I've never had a chuck lock up on the spindle since doing it that way and have never had one back off without me using the wrench to get it off.
     
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  10. hockenbery

    hockenbery AAW Advisor Staff Member

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    Ditto i doma little push with a wrench or or key to snug the chuck onto the spindle. Then a little unsung lossens it. Snapping it on will occasionally make it hard to get off. Worse to get off is one that is a bit loose and tightens when the lathe spins up.
     
  11. Zach LaPerriere

    Zach LaPerriere

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    I won't pretend to know that much about chucks, but I'll add my experience, too.

    First, I seat the chuck a little harder than John and Al on heavy bowls and for the Mega-jumbo jaws. I think every lathe has a different amount of resistance when you turn the lathe off. My General has a fair bit more resistance than a dream machine like the American Beauty. So if (and when!) I don't seat the chuck with a little gusto, heavy things just want to unthread and fly off. I'm fairly certain this would not be the case with a higher quality lathe. A person could hypothetically create this scenario, too, by overtightening the drive belt.

    Another precaution on the Megajumbo jaws is to leave the tool rest fairly close to the bowl, just in case it decides to come loose. If the tool rest is there, it will prevent the chuck from unscrewing all the way. Of course the Megajumbo jaws have a fair bit of material far out there, and thus more potential for momentum.

    So that's my own rule of thumb: How much potential momentum does the chuck and bowl have? If it's a lot, I seat the chuck by hand with a little extra momentum while turning. The plates on the Megajumbo jaws make uncrewing the chuck pretty easy, so I don't worry much about a little extra tightening.

    The second thing I've learned (the hard way of course) is to turn the empty chuck on a higher than normal speed after lubricating, and stand to the side for any tiny droplets of lubricant. So yes, go sparingly on lubricant. And yes, dust loves oil.

    The final thing to add: since I turn in a wet environment and my greenturning can throw some water, I consider how much water has gotten into the machine screws holding chuck together. I usually take my main working chuck apart after a week or two of moist rough turning to keep the bolts from corroding into the chuck body. (Also learned that one the hard way.)

    Sorry for the novel-length post!
     
  12. john lucas

    john lucas

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    Great post Zach. I do the same with larger bowls. over all the years I've turned I've only had my chuck come loose once and fortunately the tool rest stopped it from flying off. The reason it happened on me is the electronic brake on my lathe kicked in when I turned the lathe off to inspect the piece. Apparently I hadn't snugged the chuck up enough or possibly had some grit on the mating surfaces. Any way I shut the lathe off on that 20" bowl and all of the sudden it started coming unscrewed. The tool rest stopped it and only did minor damage to the lip of the bowl.
     

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