series o spindle turn down?
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  1. #1
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    Default series o spindle turn down?

    So my 11" series O has a 1 5/8x8tpi spindle nose.
    Couldnt i just turn it down and point thread it to the more standard 1 1/2x8tpi? Or is it a case of there just not being enough meat there? Dang things passthrough is only 7/8....

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    Probably could, should be plenty of meat there. Just remember you only get to fuck up once.

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    Ive got a tool post grinder i can use so the diameter should be fairly easy at least

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    Quote Originally Posted by reddogforge View Post
    Ive got a tool post grinder i can use so the diameter should be fairly easy at least
    I meant chasing the thread. Taking down the diameter is trivial but the thread might be a bit more of a challenge. I know on my 13 the thread on the spindle comes to an abrupt stop at the shoulder. You'll just need to make sure your alignment is spot on and you creep up on it as slowly as you can stand. Overcutting will result in a sloppy fit that there's no easy way to come back from. Also, I'm not sure my halfnuts allow for engagement all the way up to the spindle nose. It's been a long time since I've even thought about that, I may be wrong.

    Alternatively you could make an adapter to go from 1 5/8 - 8 to 2 1/4 - 8. I'd cut a tight fitting internal thread to screw onto your spindle and lock in place with some sort of jam screw or set screw acting as a key. The I'd turn the profile and thread in place. This would at least allow you to preserve your spindle and would pose less risk in making a mistake. If the 10L can handle a 2 1/4 - 8 thread I suppose an 11 can as well, it's just a matter of if you have room to make an adapter for it.

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    You got a lathe so you could turn and bore parts. That can/should include your spindle mount tooling. It only takes a few minutes to open a 1.5x8 backplate up to 1.625x8.

    allan

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    Quote Originally Posted by kitno455 View Post
    You got a lathe so you could turn and bore parts. That can/should include your spindle mount tooling. It only takes a few minutes to open a 1.5x8 backplate up to 1.625x8.

    allan
    Good advice. Always cut on the least expensive part.

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    Sound advice folks, thank you! Think ill not molest the spindle and make the tooling instead

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    A simple three wire measurement of lathe's spindle nose will reveal its pitch diameter. You could then compare that to the published numbers (like in Machinery's Handbook) for 1 5/8 - 8 UN to see if a standard tap would do you any good.

    This sure won't help with relief bore, but may be a way of final sizing thread after single pointing to "nearly there"

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    Try to find a cast iron object that lends its self to the job. One back plate that I made is steel with a cast iron slug in the middle.CI is less likely to get stuck on the spindle, and it threads beautifully. Do it on a faceplate if you can. It wont move when you take it off to try it.

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    which is easier and cheaper to replace ? lathe spindle or a backplate ?


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