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Thread: Live center help!

  1. #1
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    Live center help!

    I have this live center and it's causing a problem. https://woodworker.com/live-center-assembly-2mt-mssu-134-792.asp
    Photo below - it's lableled Powermatic but looks like a Oneway.

    I am turning travel coffee mugs with the stainless insert for an upcoming art/crafts fair. After drilling and hollowing the interior to fit the stainless insert I use the live center for support the mug when turning the outside to final shape and thickness. When using the large cone for support it will start to unscrew from the center while the lathe is spinning. If I don't catch it in time it can unscrew enough to jam into the mug further causing it to crack the wall of the mug.

    If it's right hand thread and the lathe is running in that same direction you would think the cone would just tighten more onto the live center but instead it starts to unscrew. I use the rod that came with it to tighten it as much as I can by hand start turning again. And, in a very short while it starts to unscrew again. This has gone on as long as I can remember owning over the last 3-4 years. But since I rarely used it I didn't think much of it. Now that I am trying to get a dosen mugs ready for this craft show it's really annoying me - especially if it causes the blank to crack.

    I'm pretty sure it's not bad internal bearing in the live center as the bearings don't make any noise when spinning the live center.

    any ideas on how to correct the problem (I'm on disability so buying a Robust live center isn't an option :-) )

    Thanks
    Ricc
    IMG_1138.jpgIMG_1137.jpg
    Attached Images Attached Images
    Last edited by Ricc Havens; 05-10-2018 at 2:18 PM. Reason: adding more info

  2. #2
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    Silly question, but, is there a set screw on it to bind it to the shaft?

  3. #3
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    Unfortunately there is not.

  4. #4
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    Quote Originally Posted by Ricc Havens View Post
    [set screw?] Unfortunately there is not.

    That looks like a much bigger cone than comes with those live centers. Are the threads tight or a little loose?

    It should tighten when the lathe is starting from a stop. But could it be unscrewing when the lathe is decelerating while stopping? That's the only reason I can think of.

    If you have a drill press and taps it wouldn't be too difficult to add a set screw. You wouldn't need threads all the way from the rim but could drill all the way sized for tapping, drill a clearance hole for the set screw, then tap just the last little bit.

    JKJ

  5. #5
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    Iíve had that same issue myself ended up ruining the large cone when it came loose.
    not sure causes it either

  6. #6
    You might try some white plumber's tape on it. Like what you would use on a garden hose. Might take up some of the slack.

  7. #7
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    Iím sure Oneway would not label their live center Powermatic, however that is probably the problem, it is not made by Oneway.

    Too loose a fit and some vibration could loosen the large cone, I would do what George advices, a wrap of teflon tape or even two would have the cone fit tightly, if you stick the pin through the center and tighten the cone firmly it should stay on, I have a Oneway live center and have not had any problems with it, and have used it enough in the 20 or so years I have had it.

    Looking at your picture I would say you do not have a Oneway live center.

    not a Oneway live center.jpg Oneway live center.jpg

    Maybe take contact with Powermatic and see what they are willing to do for you.
    Last edited by Leo Van Der Loo; 05-10-2018 at 11:54 PM.


    Have fun and take care

  8. #8
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    The chrome Powermatic live center was only a short run as Oneway objected as it looked too much like theirs, hence that is why they are black. Do you still have the point in the live center when you are using the cone? As John stated it might be from stopping the lathe as that seems like the only way it could loosen and if the point is bottoming out in the cone it would not be getting as tight as possible.

  9. Get some Loctite thread locker, the removable (blue) type. It will make the cone difficult to remove.

  10. #10
    I would suggest inserting a small rod in the holes of the live center to lock it from spinning while seating the cone on the live center. Iíve had this happen to me, but after seating the cone well, it wonít spin off.

  11. #11
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    It is a good idea to loosen the chuck slightly, bring up the cone and make it tight to the mug, then re-tighten the chuck so that the chuck holds the piece on the same axis as the cone. This will help prevent the bad cone to mug interactions you describe if the cone does come loose!

    I assume you have the tailstock tight to the bed, the cone fully engaged and tight to the mug, and the screw handle on the tailstock is tight before you start turning the outside.

    Forgive me for asking what might be a rather dumb question not having turned mugs with inserts.

    Shouldn't the livecenter/ cone being tight to the mug/insert being tight to the chuck/headstock prevent the cone from unscrewing? If so, what is moving or slipping? Is the mug insert moving deeper into the mug recess as you start to take away the wall thickness or wall strength which would shorten the mug/insert overall length? Or, is your tailstock slipping during the process?

    The distance between the head and tailstock has to increase or one of the components in the middle has to shrink in length to allow a fully threaded cone to unthread itself, right?

  12. #12
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    John J - It is the optional cone you can buy that screws onto 3/4-10tpi threads of the live center. Unfortunately it's not unscrewing as the lathe is decelerating it's doing it as I am turning. I thought about adding a set screw but there is no good place for the set screw to lock against the live center without damaging the threads of the live center.

    George H. _ I will give the plumbers tape a try. thanks for the suggestion.

    Leo - It's not the Oneway. It's made by powermatic/jet and looks like a oneway. there doesn't seem to be any slop in the threads. I use the rod to tighten it in place and use as much force as I can but it still comes loose while turning. I just re-tighten and continue turning and repeat as it comes loose again. It's just annoying. I've tried calling powermatic but the techs I have been able to talk to seem to no clue about using their wood lathes. they just want to sell me a replacement.

    Bill B. The center point is still in place. BUT - it's not bottoming out as it goes into the hollow opening of the mug blank so the point doesn't touch anything.

    Bruce S. - I will consider the loctite idea but if it's difficult to remove I'm not sure I want to go that route as I switch back and forth between center cones/points frequently.

    Hal T - I do use the rod that came with the live center to seat it as tight as it will go but no matter how tight I try it still comes loose.


    If anyone else have any other ideas please keep them coming!

    thanks
    Ricc

  13. #13
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    Dick S. - No dumb questions. Yes everything is lined up and tight including tailstock to the bed, cone being fully engaged to the mug blank, and the screw handle on the tailstock are all tight before turning. Nothing seems to be slipping or moving. It's just that the cone comes loose and as it does it will jam so hard into the mug )becasue the tailstock is tight in place and not moving) that it will either crack the mug blank or when I loosen the tailstock clamp handle I have to pull hard as the cone has unscrewed enough without the tail stock moving that it's jammed hard into the mug opening.

    Ricc

  14. #14
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    Is it possible the live center is not perfectly aligned with the headstock? I use a wooden cone on mine, and if its not centered, it vibrates like crazy. Have you tried turning the outside without the aid of the live center? Iíve done 5 so far without it, and havenít had any issues, other than the high pitched noise when wall thickness gets thin. All of mine were either segmented or staved, if that matters. Would parasitic drag in the bearing stack be the culprit?

  15. #15
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    Try to put a really fine sharpie marker on the bed at the base of the tailstock handle end. If the tailstock is creeping away from the headstock, the line will disappear as you turn. It seems as though some folks had a tailstock movement issue with Jet lathes a while back but I could be completely off base!

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