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Thread: New G0632Z-drive center (stock 2MT) stuck in headstock

  1. #1

    New G0632Z-drive center (stock 2MT) stuck in headstock

    Hello folks, having a little difficulty with getting the 2MT drive center (stock) removed from the headstock on a new G0632Z.....tried WD-40 at the spindle/taper junction with a couple hours wait...gentle /firm taping with the knockout tool.....no luck.... just trying to take the common sense approach w/o damaging my new lathe, and would love some suggestions. I've worked on this situation for 6hrs plus.... Additionally, this occurred after working on my first spindle. I checked the drive center and headstock connection with a firm insertion by hand. It was very snug and needed a tap with the knockout tool which popped it right out. There were no burrs detected on the drive center, taper however, I did not think to check inside of the drive center for any particles etc...so, shortly after with the drive center, spindle blank and tail stock setup were centered, I started on the blank. My mistake may have been too much pressure from the tail stock during setup. That is a moot point now. Have not contacted Grizzly tech support as of now, but I may have to..... Thanks for any and all input. Take care

  2. #2
    Join Date
    Jan 2004
    Location
    Lewiston, Idaho
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    27,039
    I don't have a Grizzly lathe but my knockout tool has a sliding hammer head on it. I smack mine with what ever the situation needs to remove a drive head. I can't imagine any way one could damage a headstock by hitting a stuck drive center with too much force using the knockout tool.

    BTW, I have an air hose I use at my lathe and I always blow out the headstock before inserting a drive center. I do the same thing for the tailstock when inserting live centers too.

    Since it's under warrantee, I'd call Grizzly first.
    Ken

  3. #3
    Join Date
    Mar 2013
    Location
    Eastern NC
    Posts
    153
    And I use a 12 Ga. Shotgun barrel brush to clean the MT2's.

    Whack it, firmly.

  4. #4
    Yeah, I was going to say it sounds like you are not hitting the knock-out bar hard enough. Unless it is completely galled (self-welded the taper to the socket), it WILL come free -- I mean it is a taper in socket..... If there is any damage, it has already been done -- what ever you do to dislodge the drive center now is unlikely to make it any worse. BUT, do make sure the drive center has a soft landing pad for when it does eventually come flying out of there (like maybe, a bath towel folded up and set across the ways?)

  5. I would put the knockout bar in the spindle from the other side of headstock, get a block of 2x4 and a hammer. Put 2x4 over the knockout bar, and give it a couple of good whacks. You are using too much tailstock pressure. Also, a good squirt of WD-40 or PB Blaster will help lubricate and break free.....squirt into spindle from same end you insert the knockout bar. If your knock out bar has a plastic knob on the end, take it off first.
    Remember, in a moments time, everything can change!

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  6. #6
    Join Date
    Nov 2009
    Location
    Peoria, IL
    Posts
    1,252
    I once watched Ernie Conniver shoot a stuck drive spur all the way across a stage at a public demo. Not saying it's good practice, but it was entertaining and funny after people stopped gasping at the show of force!

  7. #7
    I don't know hard you have used the knock out tool. I think the only risk in getting more aggressive with it is damaging the knock out tool. I don't see how you could hurt the lathe.

  8. #8
    Join Date
    Nov 2009
    Location
    Peoria, IL
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    The damage that can be done, is called brinelling. https://www.rexnord.com/blog/article...-is-brinelling

  9. #9
    Join Date
    Nov 2007
    Location
    NW Indiana
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    2,354
    In somewhat similar situations, I have used a hammer drill with a round bar and flat tip.

  10. #10
    Oooh, I wasn't thinking about the possibility of damage to the bearings trying to knock the drive-center out, which I suppose is a possibility, but rather of damage to the taper/socket. I guess there is also the possibility of mushrooming one end or the other of the knockout bar, or perhaps the back end of the taper....

  11. #11
    Join Date
    Feb 2008
    Location
    lufkin tx
    Posts
    2,036
    Quote Originally Posted by Timothy Thorpe Allen View Post
    Oooh, I wasn't thinking about the possibility of damage to the bearings trying to knock the drive-center out, which I suppose is a possibility, but rather of damage to the taper/socket. I guess there is also the possibility of mushrooming one end or the other of the knockout bar, or perhaps the back end of the taper....
    For anything stuck in metal--nothing beats Liquid Wrench applied and wait overnite. A heavy solid tap(no wood buffer) should do it. If all this fails a BIT of heat on the spindle will do it. Only a bit.

  12. #12
    Join Date
    Dec 2012
    Location
    Brenham, Tx
    Posts
    104
    I'll tell you how to get it out. It happened to me on my new PM3520. Put a pipe wrench on the drive center. Lock the spindle. Wack the pipe wrench handle. It'll break free. Yes you'll have a few teeth marks on your new drive spur. It won't affect it's ability to hold something.
    You wan't it out or not?

  13. #13
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    8,339
    Quote Originally Posted by Robert Edington View Post
    I'll tell you how to get it out. It happened to me on my new PM3520. Put a pipe wrench on the drive center. Lock the spindle. Wack the pipe wrench handle. It'll break free...
    Another thing to try to loosen metal-to-metal stubbornness - heat the outer part and/or cool the inner. Can't see taking a torch to a lathe spindle but I can see holding dry ice on the drive center, or maybe spraying the end with freeze spray. I've done this to get things apart and put them together. Works for bearings. I don't know how it well it will work for a smaller diameter.

    Tapers can be oh so stubborn. I used an industrial SDS hammer drill on equipment pins, in the hammer/chisel mode. I did have one huge tapered pin holding the hydraulic cylinder on my skid steer boom that I couldn't get out. I tried everything including smacking on it with a big sledge hammer against a 1" dia rod. I gave up after soaking a day or so with Knock'er Loose then beating on it half the morning so I finally loaded the machine on the trailer and took it to the John Deere equipment shop. When I went to pick it up a couple of hours later I asked the guy how he got it out. Said I just needed a bigger hammer!

    JKJ

  14. #14
    Got it out! Tried a couple other approaches mentioned in this thread...nope. Finally, picked up a solid, heavy steel rod that was the same diameter as the knockout.....it was long and heavy enough to give me the extra mass needed. Several hits with a hammer, no luck. So, with a little frustration (recalling that an aggressive approach is ok) I hit it about a half dozen times and out it came. I did set up a an area that was well padded and plenty of room to catch the center...or so I thought. The thing came out fast and hard. As a result, there are a couple tiny burrs that can be quickly knocked off with a piece of 400 wet/dry. Major lesson learned...watch tail stock pressure etc. This is a good thread with a lot of practical information not found elsewhere. Thanks everyone and take care

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