"Arbors" are they all straight?

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  • #49878
    disciple_dan
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    Hey, Ya’ll. I’m haveing some trouble polishing pivots in my lathe. A lot of them seem to be a little bent. Is it common for arbors to not be exactly straight? I thought it could be my lathe and I do think it is a little off ( Grizzly 8688) but I still think I’m finding crooked arbors. Any ideas?

    #64129
    bernie weishapl
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    Dan I very seldom find a bent pivot in clocks unless someone else has worked on it and bent them putting back together. I polish mine in a jewelers lathe. I use one of these to check pivots before I polish them. http://timesavers.com/i-8948851-plate-spreader.html That way I can straighten them before polishing them. Like I said I very seldom find bent pivots upon disassembly.

    #64130
    disciple_dan
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    Thanks, Bernie. Yeah, I wish I could have gotten a jewelers lathe. I just didn’t know enough about them to know what I was buying. I just couldn’t bring myself to buy, sight unseen, something I knew so little about. I think in time I will be able t make this Grizzly 8688 do what I need it to do.

    I’m not talking about bent pivots as much as crooked arbors. Arbors that have a camber. When I chuck one up in the 3 jaw head of my lathe, I spin it in the jaw just a bit to make sure it is in the jaw straight and most of the time it will have a definite wobble. Not always but I would say more than 50%.
    This information is base on only the 3 clocks that I am working now. I’ve not used the lathe very long.
    I’m just wondering if it is something I’m doing wrong or if it might be my lathe or what it might be.
    Thanks for your help, Danny

    #64131
    bernie weishapl
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    Dan I am just going off 30 some years experience and I have never seen 3 clocks with a whole bunch of crooked or bent pivots. Maybe one. My 3 jaw chuck in my Taig lathe had to be trued up to make it run accurately. The jaws are aluminum so it was easy to do. They were off by a few thousandth so that could be your problem. That is why I use jewelers lathe with collets because they are true. You can find them on ebay or here at Uncle Larry’s. http://www.execulink.com/~lfoord/tools.html Scroll down to the lathes and look at #3512 which is complete with collets, motor, gravers, and pretty much ready to go. Even with my Taig trued I don’t use it to check pivots for being straight. But that is just me. Don’t trust 3 jaw chucks.

    #64132
    willofiam
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    Danny, bent arbors come along often, some worse that others….possibly from torque over the years, previous mishandling, ect…ect… What you want to check for is straightness from one pivot to the other. Dont use the lathe to check, use something with 2 parallel straight edges, can even use the edge of the plates when put together. Roll the arbor along them and watch the pivots carefully.

    #64133
    disciple_dan
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    • Topics Started: 20
    • Total Posts: 127

    Hey, Thanks, Bernie and William. Great advice. I wish I had a jewelers lathe. As soon as I am able I will get one. I got some ER25 collets for this lathe but they only go down to 1.0 mm. I’m looking for some smaller ones but haven’t found any. I try them on the pivot They can handle.
    I have yet again a small clock that just won’t go. It has been bushed in the past with bushings that have a large shoulder on the outside. Ever seen those? They are very large. The pivots are 0.8 mm and the hole for this bushing is 3.0 mm I don’t have any bushings that large with a 0.8 bore. I don’t know how to make any yet. I’m sure I will find some.
    Anyway, This clock will not run. It’s a repeat of the Schatz cuckoo. I am beginning to think it is just a power loss and not the anchor at all. I have a lot of trouble deciding if a hole is worn in these small clocks.
    I’ll just keep plugging away at it.
    Thanks again, Danny

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disciple_dan"Arbors" are they all straight?