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Accidentally Spun A Chuck On Under Power

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  • Accidentally Spun A Chuck On Under Power

    I turned on the lathe without the chuck all the way on. I was centering a piece in a 4 jaw, and had backed it off without noticing. Well, I knew it was going to be trouble as soon as I heard the whack of the chuck seating. I tried everything. Impact on a piece of hex bar, piece of plywood against the bed and a socket & breaker bar on hex stock bumping it in reverse. It was not budging, and I know better than to try the back gear. I though about it, and was looking at the hole in the end of the spindle where a collet closer pins on. I though if I could make an inner and outer diameter that just fit on the spindle end like a socket so there was no room for anything to deform in any direction, and I put a pin though all three pieces, that pin in shear like that would take a fair amount of force without breaking. A little turning, welding, drilling, and voilĂ ! Locked it solid, and it came off. Took a dial gauge to it, and it is still straight. Wasted an entire day. There is a mistake I wont make again.





    Last edited by junkaddict; 05-05-2021, 12:21 AM.

  • #2
    Nice recovery!

    When I read the title my first thoughts were "he won't do that again"
    Peter - novice home machinist, modern motorcycle enthusiast.

    Denford Viceroy 280 Synchro (11 x 24)
    Herbert 0V adapted to R8 by 'Sir John'.
    Monarch 10EE 1942

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    • #3
      A great solution! Good job you didn't start it up in reverse.
      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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      • #4
        Originally posted by junkaddict View Post
        [snip]
        There is a mistake I wont make again.
        ...
        Yahbutt ... you just might want to save that spindle-end "wrench" ... just in case. It's presence will have an added benefit of reminding you of your little blunder. Nice(!) save BTW!

        The rest of us might want to consider how we would get out of a worst case chuck lock up.

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        • #5
          Thanks Junk, I think I'm going to resort to this on a friends Heavy 10 he just bought. He called me cussing a couple weeks ago and what little I've seen of this machine there's no other way to hold the spindle. Based on his rantings it's probably stuck like yours was. I'll have him make that holder about 8 inches long to fit in the spindle so it can't cock on the end of the spindle.
          Last edited by I make chips; 05-05-2021, 09:40 AM.

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          • #6
            It's nice to hear from somebody who can solve problems without whining about it. You will probably never need those tools again, but don't be tempted to repurpose them.

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            • #7
              Oh you might need them again. Not because you've made the same mistake, i'm sure you won't, but heavy cuts, especially intermittent ones can jam a chuck on pretty tightly.
              'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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              • #8
                Wow --- sucker was on there, that momentum thing can get you every time but nice work and safe for the machine too - kudos JA...

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                • #9
                  After that episode, I would fit the backplate without the chuck and check the front face with a dti, and skim if necessary. Also, check the plate for any cracks.

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                  • #10
                    Ya, I stuck a chuck on my buddy's Dalton. I didn't have it all the way on.... not noticing, I started a cut, and screwed the chuck on that last little bit. It seated with a clunk. I tried the methods used by the OP, and had the same luck. I wound up removing the chuck from the backplate, and machining the plate off the spindle.
                    I cut it off twice; it's still too short
                    Oregon, USA

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                    • #11
                      Nice recovery!

                      When I read the title my first thoughts were "he won't do that again"
                      Peter - novice home machinist, modern motorcycle enthusiast.

                      Denford Viceroy 280 Synchro (11 x 24)
                      Herbert 0V adapted to R8 by 'Sir John'.
                      Monarch 10EE 1942

                      Comment


                      • #12
                        There's some sellers on eBay that have 3D printed "gear wedges", or whatever they call them. They're literally a wedge with matching female gear teeth on two faces, meant for this kind of thing. You seat it between- I'm guessing- the bull gear and back gear, or some other convenient ones (they're printed to fit certain spots on certain home-shop machines.)

                        That locks the gears like engaging the back gear, but spreads the load out over a couple inches of gear teeth. And being soft plastic, is going to fail long before even cast iron teeth.

                        I'm not sure what they're called, and of course now that I'm actually looking for one, I can't find it, but that sort of thing is an option in cases like this.

                        Doc.
                        Doc's Machine. (Probably not what you expect.)

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                        • #13
                          Just like you did, I figured the trick is support the pin right at the shaft. I had one, looks like it was glued on, that really taxed me. braces and belt maybe , but I made something that both clamped on the shaft and engaged the pin. Not to suggest you were wailing on it, but learned with a few projects recently that 100 or 500 or whatever little taps can often free something up vs one big one that breaks things. Its amazing how well it can work. 24: adjustable on the clamp, big pipe wrench on the stuck collect chuck....I was worried about the amount of torque required bending something, but no harm done, spindle was 1/2 a tenth run out afterward







                          in Toronto Ontario - where are you?

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                          • #14
                            Congratulations. You now know that the backside of your chuck is perfectly flat with respect to the spindle
                            Yep, I did the same thing once... and *only* once. My solution involved using a leather belt for a strap wrench, and a 1-kg (2-lb) brass hammer

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                            • #15
                              ...I thought you were exaggerating when you said "glued". (I also briefly thought "where did you get a ten-foot-long Crescent Wrench?!?" )

                              Over on PM, a fellow- I think John Oder?- made a giant "clamp wrench", lined with brake-lining material, in order to break loose something like an 18" faceplate, that had probably been on that threaded spindle for half a century or more.

                              Doc.
                              Doc's Machine. (Probably not what you expect.)

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