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Recovering from lathe crash Jet 1024p

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  • Recovering from lathe crash Jet 1024p

    Was turning down the OD of a back plate for my 4-jaw. Running back gear and slow power feeding close to the headstock, not much room for error. I didn't disengage quick enough and everything came to an abrupt stop, the side of the apron hit the side of the quick change gearbox and simply couldn't travel any farther. I powered down immediately. Apron was seized. Got it free and everything is functional except when I crank the carriage by hand it goes from normal to tight and repeats. Disgusted at my mistake I walked away.

    Looked at it today. With the apron removed from the lathe the problem still existed. I narrowed it down to the engagement of 2 gears then based on the repeatable position of the tightness I feel I have narrowed it to one gear. The one that the crank handle shaft teeth mesh with. It's a 50-toother about 4.1" in diameter.

    At a glance there doesn't appear to be any major trauma to this gear. Closer analysis with a camera shows some beat up teeth but nothing I would consider "trashed." No chunks missing, no teeth bent. I wouldn't think the condition issues I found would cause this if I weren't looking for a cause.

    Replacement parts aren't available through Jet or for the same model branded as Grizzly and Enco. As a beginner I haven't "cut my teeth" yet in the gear making arena and am not yet equipped to do so. Before jumping in too deep too quick what's the consensus on lightly "deburring" the teeth in question. Perhaps with a hand file or a heavy duty wire cup?

  • #2
    While it could be damage to the gear teeth (with could be remedied with careful stoning), it is just as likely that there's a bent shaft or bent gear.


    • #3
      Does the clearance between gears change? A slightly bent shaft seems possible.

      Okay, I'll add the +1 now
      Last edited by fixerdave; 05-31-2014, 02:28 PM. Reason: Obviously, I type (or think) too slow


      • #4
        Most probably the shaft is bent, so it shows up as eccentric movement of the gear and thus binds once every turn.
        Amount of experience is in direct proportion to the value of broken equipment.


        • #5
          You'll fix it, it happens to everyone at least once!, mate of mine bought a myford and put a wooden block between the headstock and the carriage just in case it got too close, jammed the block and pushed the headstock off the bed!, poor thing


          • #6
            Clumsy bastard

            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


            • #7
              I got a Jet 1024P about 30 years ago, and early on I did something similar. As I recall I didn't damage any gears or shafts, I just sheared a pin that affixes a gear to its shaft. A lot of work to dismantle the apron, but a successful repair. Of course, the lead screw must be removed from the lathe before taking the apron off, so when I put it back I had a bright idea. The lead screw was affixed to the QC gearbox with a steel taper pin. (I have one of the early 1024s without a separate feed rod.) I made a brass one to replace it with, and a spare as well. All was good. Fast forward to about a year ago. My attention drifted at the wrong time... BANG! I had sheared that brass pin. I actually remembered where I had stored the spare, and was running again in minutes! I now have a couple of aluminum pins on hand now, as I believe the brass ones are stronger than need be.


              • #8
                Now that Sir John has said his obligatory remark:

                The other guys beat me to it, I'd suspect a bent shaft messing up the mating between the gears you have narrowed the issue to. If it ends up being a gear, you ought to be able to find a standard part that can be modified to work, if it comes to that.
                I have one of these same lathes, an older one made in the early 80's. It's a pretty nice machine overall. When I got my Sheldon I figured I'd sell the Jet, but I ended up keeping both. It will be worth the trouble to fix. Do let us know what you find.


                • #9
                  Confirmed, bent shaft. I had considered this before removing the gear but discounted it because the gear didn't seem to be wobbling and was very close to the inside wall of the apron which I thought made it easy to eyeball. I just broke out the surface plate and sure enough... wibble-wobble. I know I'll fix it somehow. If I can't find a part I'll make a part. But it might require buying more tooling. Darn! Looks like Grizzly branded a similar if not identical model and the part might be available. I just need to try to confirm its specifications.

                  My lathe is a Jet 1024P (10" x 24") This bent shaft measures 16mm dia shank with a 22.5mm dia spline on the end with 13 teeth. Jet manual says Part "IA-0340"

                  Grizzly's G9249 (12"x37") lathe looks identical and the manual lists part no. "P9249336" GEAR SHAFT 116T X 16

                  The Grizzly's apron diagram is VERY similar but the drawing of the shaft looks a little different. I suppose the next easiest thing would be to find a spline shaft of the right size and turn down the shank but that's unlikely I will find something. Will continue to explore options, might end up having to learn to make one which isn't necessarily a bad thing. Gotta learn sometime!


                  • #10

                    120 mm OAL
                    16 mm dia shaft
                    22.5 mm dia spline
                    13 teeth

                    I suppose I could try straightening it in the press but that seems awful hit or miss.


                    • #11
                      I think you can turn it down to remove the bend, affix a sleeve, and turn it to the correct dimension. You can chuck it on the splined end, center drill the other end for using a live center (mandatory with that much overhang), then go to work.
                      Any products mentioned in my posts have been endorsed by their manufacturer.


                      • #12
                        If it was mine, I would take a stab at straightening it. Do you have a press, or know someone who does?


                        • #13
                          Ok, fixed it...

                          I straightened it in two places using two methods.

                          Act 1. The shank had a very slight bend, a light nudge in the press fixed that.

                          Act 2. The 22.5mm toothed "head" was bent severely at the tiny "neck" where it meets the 16mm shank. I put it in the vise protecting the shank with aluminum flashing so only the larger spline head was sticking out. Then I beat on the spline part with my trusty lead hammer, removed, checked, repeat... about 8 cycles of this and it seems freakishly perfect. I have reassembled the apron and the problem appears resolved.

                          Before and after...

                          Also, I think the idea of turning it down and sleeving it is genius. I will have to remember that for future needs.


                          • #14
                            Maybe because their owners are more likely to need it, the later Atlas lathes have a slip clutch on the feed screw.

                            Congratulations on a successful repair!
                            Don Young


                            • #15
                              Wow!! That's a lot more bend than I was thinking it would have. Nice job on the repair.
                              Any products mentioned in my posts have been endorsed by their manufacturer.