JET 12 X 40 threading problem

Jubil

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If I’m seeing what I think I’m seeing in the diagram, that gear is installed backward. And possibly not engaging key as it should. But that doesn’t help dismantling it at all.

Chuck
 

eugene13

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As I said, it was a fluster cluck; the radial bearing (78) was stuck on the shaft and the hole that the flange fits into is tapered, I couldn't figure what was holding it in. After I got everything broke loose it came right out. The root cause of the problem was the person who assembled the gearbox, evidently they couldn't get the gear on the shaft so they filed down the key and the resulting sloppy fit wallowed out the keyway in the gear, the shaft keyway is OK so now I am waiting on parts, oh well, If ya got time to lean ya got time to clean.
 

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Mitch Alsup

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WoW !! How many of these barrel threads have you cut on this lathe to have so wallowed out that key slot ?
 

eugene13

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WoW !! How many of these barrel threads have you cut on this lathe to have so wallowed out that key slot ?
I bought the lathe new twelve years ago and have only threaded with it a few times, the high side threads have always been poor quality but the low side have always worked fine. Cheap Chinese labor, you get what you pay for.
 

eugene13

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I'm back, hollering for help again. I got my parts but they sent the wrong thing for a retaining ring (snap ring) I need a 15mm external snap ring (MSH-15) I only need to buy one, thanks.
 

eugene13

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Finally got it back together and it still does the same thing, now I'm starting to think operator error
 

SLK001

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I reread your first post. If your tool dug in, then your problems most likely are in your carriage. Do you have a lot of backlash in your cross or compound leadscrews?

Your cut of 0.001" shouldn't have caused any issues. My guess, is that your backlash isn't being taken up properly and the work piece is pulling in the rest of the backlash into the cut.
 

eugene13

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I reread your first post. If your tool dug in, then your problems most likely are in your carriage. Do you have a lot of backlash in your cross or compound leadscrews?

Your cut of 0.001" shouldn't have caused any issues. My guess, is that your backlash isn't being taken up properly and the work piece is pulling in the rest of the backlash into the cut.
Thanks, I've checked all that and snugged everything up, I have .010 backlash on the leadscrew. I also opened up the headstock and inspected every gear in the train, I ran about 50 passes and had no malfunction in aluminum. Replacing the gear made it thread "better", if it does it again threading in steel I will blame it on tool springing or operator error. thanks again for your help.
 
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