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  1. #21
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    Default Re: Collet closer vibration



    This is how bad mine wobbles. I tried to link right to the part that wobbles but if that didnt work its at 8:20.

    Jesse



  2. #22
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    Default Re: Collet closer vibration

    It is a shame that the JFK website is nothing more than a start up site. Very little info there.
    I did send them an email asking about replacement parts. I am sure I could make a new locking pin or repair this one myself, but I would still like to see if it is possible to replace other parts in the future.
    Installation instructions would not hurt my feelings at all either.

    Nice video, Jesse. Looks like you have the updated closer. Hopefully we can get this movement resolved.

    Lee


  3. #23
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    Default Re: Collet closer vibration

    A little more troubleshooting today on this. I found out that when you tighten up the yoke mount for the arm to the lathe, then it binds. That is part of the problem on mine.
    The other part is if I raise the yoke up to be on center for the tube, then the closer adjustment is hard to operate and the collets are hard to start.
    So with the yoke mounting bracket loosened and backed off the top and bottom uhhh throw yoke loosened up, it all ran pretty smoothly.
    That spanner nut continues to back off though. There is no flat anywhere on that part to get it tight like it should be. Also that outer collar is a stop collar. It should be where it is.

    Then I broke out the dial indicator. Well, the big black mounting collar that the little indexing ring mounts to is off. Way off really. I don't think I aligned that part with an indicator and if I did, it moved.
    No need to indicate the indexing ring if that part is not correct. I will tear into this again next weekend. Break it all down and start from scratch. I wasn't happy to see my encoder pulley is not running true either. Shoot, I would be shaking too if all my parts were misaligned like that.
    Anyway a little longer won't hurt it at this point. I want to design a belt cover with an access door or two anyway.

    Here is a bit of video. The phone is actually on the lever at one point, so loosening everything up smoothed it right out. That there is crazy I tell yah.




    Lee


  4. #24
    Gold Member LeeWay's Avatar
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    Default Re: Collet closer vibration

    I decided that with some parts loose, it was not safe to operate, so I did the alignment today. First three clips are what I found. Last two are how close I got it. Notice that the actual pulley on the lathe is not very well aligned either. Not sure if it is possible to get it closer or not, but it is running pretty smooth now with everything tightened back up. The throw yoke is still not centered. I think I need to add more shims under the rod mounting block to lift it up. It is also pulling down just a bit on my air cylinder shaft, so it needs to come up. I have .015" worth of shims in there now. I think it can use at least .02" more. Other than the misalignment there, everything else about it works better than it every has.
    I also tweaked just a bit on my encoder pulley and it is running a lot truer as well. The next time I do it, I will tear it down to the bare bones on the drive side of the spindle and start from scratch.



    Lee


  5. #25
    Gold Member MichaelHenry's Avatar
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    Default Re: Collet closer vibration

    Lee - your video is marked "Private" by YouTube...



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    Default Re: Collet closer vibration

    Did that fix it?

    Lee


  7. #27
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    Default Re: Collet closer vibration

    Yes - it seems to be visible now. Thanks.



  8. #28
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    Default Re: Collet closer vibration

    Did anyone check the pulley before assembling the collet closer?

    Lee


  9. #29
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    Default Re: Collet closer vibration

    I didn't think to do that, but will try to do so the next time that area needs maintenance.



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    Default Re: Collet closer vibration

    Thanks, Michael.
    I mentioned that everything about it seems to be working better than ever before. This is true for collet installation as well. It took a little effort before to spin the ring onto the collet threads and adjust it correctly. Now it almost freewheels onto it. Much easier to operate.

    On some of the videos I have seen, guys mention that they have to machine the throw yoke to gain clearance on the left side. That is adjustable with the mounting rod. Shorten it up some and it will pull that assembly to the left closer to the centerline.
    Now about the threaded rod mounting block. The holes in mine are too close of a tolerance to the cap screws to allow for much tilting. I will have to enlarge them one size to get more shims under it and allow the top of it to touch. A better solution might be to make a new mounting bracket. I am not sure at this point if the holes in the lathe are too low or the mounting bracket flange isn't 90 degrees to the pivot point. Would need to check closer for the fix on that. It is a main contributor to binding and that is part of the vibrating issue.

    Lee


  11. #31
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    Default Re: Collet closer vibration

    The threaded rod is kind of a crappy design, what should be there, *I think* would be more of an i-beam shape aluminum strut that resists bending in the vertical axis.
    For the mean time. I just bent the rod down a hair, by just pushing on it. The whole assy seems to be in a better place. The parts I make don't cycle that fast so just taking the handle off after it's clamped is a big help. The handle is a vibration amplifier if anything.



  12. #32
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    Default Re: Collet closer vibration

    Quote Originally Posted by MichaelHenry View Post
    Mine doesn't seem to vibrate in use but it is a bit tricky to get the drawbar started on a collet. I'm hoping that either gets better with use or that I'll find a way to adjust the drawbar so that it aligns better with the spindle axis.
    Just a correction on the above statement - I was testing again today and noticed closer vibration once the spindle got to 2,000 rpm. This thread has gained renewed interest for me <g>.



  13. #33
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    Default Re: Collet closer vibration

    Sure it isn't a resonance issue at 2000 rpm? Did it continue once you got up to 2200 or so?

    Tim
    Tormach 1100-3 mill, Grizzly G0709 lathe, PM935 mill, SolidWorks, HSMWorks.


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    Gold Member MichaelHenry's Avatar
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    Default Re: Collet closer vibration

    Quote Originally Posted by tmarks11 View Post
    Sure it isn't a resonance issue at 2000 rpm? Did it continue once you got up to 2200 or so?
    Nope, pretty much present at all speeds from 1500 to 2500 and seems to fall off below 1500 rpm. I have the chuck pulley installed so am limited to 2500 rpm max.



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    Default Re: Collet closer vibration

    I received my Slant Pro lathe in Feb of this year and finally had a chance to look into the collet closer vibration last month. After carefully indicating the index ring (< .001”) the run out of the assembly was still greater than .015”, which resulted in vibration at speed.

    I too contacted JFK and although they were very nice, they were not very helpful in diagnosing the issue.

    After some experimentation, I noticed that clamping and then re-clamping the same work piece would affect the amount of run out and vibration. This led me to look at the index ring through hole and outside diameter of the draw tube. My factory index ring has a through hole that was .015” larger in diameter than the draw tube. This amount of clearance allows the draw tube to move off center. With this arrangement, the alignment of the assembly is maintained by the collet in the spindle nose and the three fingers on the cam, which in theory should keep the draw tube centered, but in practice does not.

    My solution was to make a new index ring with tighter tolerance on the through hole and a larger bearing area (full thickness of the ring) to be in contact with the draw tube OD. My draw tube measures 1.351” OD and the through hole on my new index ring is 1.355”ID.

    This change in combination with careful adjustment of the collet closer arm and bearing pins has nearly eliminated the vibration.



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    Default Re: Collet closer vibration

    Quote Originally Posted by Renovo View Post
    I received my Slant Pro lathe in Feb of this year and finally had a chance to look into the collet closer vibration last month. After carefully indicating the index ring (< .001”) the run out of the assembly was still greater than .015”, which resulted in vibration at speed.

    I too contacted JFK and although they were very nice, they were not very helpful in diagnosing the issue.

    After some experimentation, I noticed that clamping and then re-clamping the same work piece would affect the amount of run out and vibration. This led me to look at the index ring through hole and outside diameter of the draw tube. My factory index ring has a through hole that was .015” larger in diameter than the draw tube. This amount of clearance allows the draw tube to move off center. With this arrangement, the alignment of the assembly is maintained by the collet in the spindle nose and the three fingers on the cam, which in theory should keep the draw tube centered, but in practice does not.

    My solution was to make a new index ring with tighter tolerance on the through hole and a larger bearing area (full thickness of the ring) to be in contact with the draw tube OD. My draw tube measures 1.351” OD and the through hole on my new index ring is 1.355”ID.

    This change in combination with careful adjustment of the collet closer arm and bearing pins has nearly eliminated the vibration.
    Holy cow! My index rind ID is 1.3715 .. my draw tube is 1.3425 ... .029! Ideally a .003 clearance at this diameter should be plenty! Thanks, Renovo, for this insight.



  17. #37
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    Default Re: Collet closer vibration

    Quote Originally Posted by Renovo View Post
    My solution was to make a new index ring with tighter tolerance on the through hole and a larger bearing area (full thickness of the ring) to be in contact with the draw tube OD. My draw tube measures 1.351” OD and the through hole on my new index ring is 1.355”ID.
    Please provide feedback on your design changes to JFK so they can improve their product line.

    Tim
    Tormach 1100-3 mill, Grizzly G0709 lathe, PM935 mill, SolidWorks, HSMWorks.


  18. #38
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    Default Re: Collet closer vibration

    Good thought and I will follow up with them.



  19. #39
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    Default Re: Collet closer vibration

    Hope this helps. FYI, the OD of my draw tube was not consistent along the entire length. There is a reduce section near the collar.



  20. #40
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    Default Re: Collet closer vibration

    I had quite a severe wabble on mine and ended up disassembling it to track it down. The ID of the index ring on mine is .015 larger than the draw tube, which in my opinion is too much and is an issue, as discussed previously in this thread. However, that's not the primary issue with mine. The primary issue is the journal that the large throw yoke bearing rides on has a LOT of runout with respect to the other portions of this piece, such as the tapered portion that pulls the cams, leading to large visible and measurable movements. I pulled the spanner nut and bearing, and set up the piece on a small lathe. I have two indicators simultaneously on the piece, showing the runout. No amount of adjustment or shimming of anything is ever going to get this out. This is a defective part. I'm headed to JFK tomorrow to see if I can get a replacement.




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