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Run threaded spindle in reverse

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  • Run threaded spindle in reverse

    I made a washer to keep my chuck from unscrewing when running lathe in reverse. I took chuck off faceplate and had enough room to put a .150 thick washer between faceplate and chuck. Then I used another washer at back of spindle with a 1/2 13 threaded rod and nuts to lock chuck to spindle.


    jimsehr


    https://lh5.googleusercontent.com/X7...w368-h207-p-no

  • #2
    The thumbnails are too small to really see what you did.

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    • #3
      Seems like that solution prevents thru the spindle turning, though. Better than nothing, I guess.

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      • #4
        Ever have a chuck come off?

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        • #5
          The chuck is probably more apt to come off WITH a washer. I've never had mine loosen. I just did a bunch of reverse turning this past week. If the seats are clean and true, most of time you'll need some intelligent persuasion to get loose. Perhaps you're not installing the chuck correctly.

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          • #6
            If you run a threaded spindle in reverse, it's not a matter of if the chuck will come off, it's a matter of when the chuck will come off. I've seen it happen many times and it's not pretty. Luckily I don't know of anyone who was hurt in the process, except for the lathes.

            I couldn't see the pictures either, so I don't know for sure what you are doing.

            Tom
            Tom's Techniques

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            • #7
              Looks to me he basically made a drawbar for his chuck. A large washer ("metal disk") is captured between the back of the chuck and its mounting plate. As mentioned, the result precludes the ability to hold long work through the spindle. The "drawbar" is a solid, threaded rod.

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              • #8
                I avoid running in reverse for that very reason. The thought of a 25 lb chuck bouncing around @ 600 rpm scares me. Fortunately, I have a lathe available that CAN run in reverse. Bob.

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                • #9
                  This works for me and it doesn't tie up the spindle bore for long work. Not my invention but some threaded spindle lathes do share this feature.
                  Of course you do need room on the end of the spindle for the retention groove.

                  Home, down in the valley behind the Red Angus
                  Bad Decisions Make Good Stories​

                  Location: British Columbia

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                  • #10
                    I blew up the pix in photoshop, and it appears that the OP's chuck is mounted with an adaptor plate. He put a washer and nut between the adaptor plate and the chuck. The threaded rod extends through the spindle where another washer and nut holds it in place, preventing the chuck from unscrewing. I was thinking along the same lines because I had a chuck unscrew going forwards. It was not tight, and I had the bels drive set for high speed. When I shut the motor off, the spindle stoped, but the chuck was still turning due to it's mass. Fortunately, the jaws were not extended, so I was able to catch the chuck and slow it enough so it didn't unscrew entirely, but it was close! Phew!

                    John

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                    • #11
                      The Weiler and other European lathes with the threaded spindle (DIN 60X4) is complimented with spindle tooling that provide for the fitting of CLAMP COLLARS

                      Much like any shaft collar with a tangent pinch bolt, when clamped down, the surfaces of the smooth spigot are brought together. OD of the spindle, and ID of the tooling adaptor.

                      No need to bump the chuck thread "tight". The chuck never budges during reverse operation, and when released, the chuck comes right off again!

                      I've wondered why all threaded spindles are not supplied with similar devices!

                      ps

                      the machine is on a VFD, with a .8 second stop ramp. It hauls right down from speed, and even reverses in a moments time.

                      I have no fear that the chuck will come adrift with the clamping collar securing the works.

                      Options ...

                      Cal

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                      • #12
                        About the only time I run the spindle in reverse is when inside threading away from the spindle. I have been using threaded spindle lathes for over 50 years and never had a chuck come off. It only takes a few minutes to take the retaining washer out of the chuck. Then go back to run spindle in forward. And I have never ran spindle in reverse when bar stock was running through spindle. But I have ran collets in reverse with facing tool upside down using a roller steady rest and only the two bottom rollers for faster loading and facing and chamfering thousands of 1/2 dia shafts. Using a collet with a stop like this you don't have to stop spindle.
                        jimsehr

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                        • #13
                          Threaded spindles was one (of many) reason I traded in my SB's on my Logan as it has a D1-4 spindle nose.

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                          • #14
                            The only time I run my spindle in reverse is when I'm tapping holes.
                            My RPM's low, and it's never come loose.

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                            • #15
                              Every lathe I have run with a threaded spindle had no problem working in reverse. But then I learned how to properly mount a chuck on a threaded spindle. Only lathe I ever knew to lose a chuck was one with a clutch that had something worn inside that caused the clutch to lock up and then all the slack went out and stated the spindle instantly. The jerk was hard enough to loosen the scroll and drop the workpiece...

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