How to avoid this machine crash
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  1. #1
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    Default How to avoid this machine crash

    Turning a simple part in a CNC lathe, face, turn, thread, groove and cut off, 30 part run, the back side will be done in a second op. On the 21st part, at cutoff the part flips into the counter bore in a chuck jaw at just the wrong time, and smacks the turret hard enough to stop the chuck and knock the turret out of alignment. Never seen that happen in 30 years of CNC lathe operation. Does anyone go to the trouble of putting caps into the counter bores of the jaws of their 3 jaw to avoid something like this? Or is there some other trick? Or is this just a once in a lifetime piece of bad luck?

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  3. #2
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    Try running larger parts that won't fit in the c'bores.

    Sorry, couldn't help myself.

    Keep some plastic plugs around that fit the cbore's like the plugs they stuff in air / hydraulic fittings to keep dirt out. Only need them in the inside screws.

  4. #3
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    Hang the stock out farther so the part doesn’t get wedged between the cutoff and jaws?

  5. #4
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    Collet chuck.

    Sent from my SM-G930V using Tapatalk

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    If you are using soft jaws, cut the jaws at a 45 to give you more clearance.

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  8. #6
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    I think that falls into the category of 'head scratcher' or 'I'll be damned'

    Sent from my SM-G973U using Tapatalk

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  10. #7
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    I'd be willing to bet that scenario never happens again. But Murphy is a bitch, and I don't gamble for a reason.

    R

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  12. #8
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    Quote Originally Posted by litlerob1 View Post
    I'd be willing to bet that scenario never happens again. But Murphy is a bitch, and I don't gamble for a reason.

    R
    yup me too, I always wondered what would happen now I know.
    only thing that has happened to me like this is denting doors and covers and it doesnt happen alot. one reason I got collet noses.

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    Don't part it completely off, leave just a tiny bit so that you can break it off easily with your hand.

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  15. #10
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    I like this solution the best. Won't have to fish around in the chip to find parts.

  16. #11
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    I was running a ton of brass parts in the past and just drilled and tapped some 1/4-20 holes in the face of the chuck and made a 8" disk to cover the face of the chuck .. put three slots in the plastic disk and would center it by eye ball and tighten one bolt tight and dent the threads on the other two bolts and leave them like 1/4 turn loose so the chuck could open and close .. ran the same Disk for years ,, it keep the chips and parts from flying all over hell from the chuck jaws acting like a fan ...

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