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Trying to remove a stuck post in casting

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  • Fasttrack
    replied
    Originally posted by Mcgyver
    I confess I didn't know the washer trick. In trying to think how/why, with no space, there is no distance for the threaded section to stretch which is what gives you the holding power.....ie the inclined plane of the thread strains the fastener along its axis creating the force holding it together. maybe that's why they break without a space - ie all the force shows over a very short section so is more torque twisting it than strain elongating it?

    best I could come up with
    It broke at the casting, not where the double nuts were. Of course, the nuts I'm accustomed to have a slightly raised bearing surface - the threads terminate before the face of the nut.

    Even with the threads right up against each other, it shouldn't matter. You are still straining the fastener along the axis, except that the strain is localized to the root of the thread between the two nuts. I can believe that adding a washer makes it easier to implement, but I can't see why (either theoretically or based on experience) that it is neccessary.

    Edit: LHC, if you do happen to break the stud at the casting, instead of drilling it out, consider using a torch. Cast iron won't burn like the steel so you can often carefully blow the steel out and leave the threads intact. I've done that several times after someone here told me about it.
    Last edited by Fasttrack; 04-29-2012, 01:50 PM.

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  • Mcgyver
    replied
    I confess I didn't know the washer trick. In trying to think how/why, with no space, there is no distance for the threaded section to stretch which is what gives you the holding power.....ie the inclined plane of the thread strains the fastener along its axis creating the force holding it together. maybe that's why they break without a space - ie all the force shows over a very short section so is more torque twisting it than strain elongating it?

    best I could come up with

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  • Fasttrack
    replied
    Originally posted by duckman
    Why is it nobody remembers to put a washer between the nuts when your trying to remove a stud, 2 nuts won't lock.
    ... I broke a 3/8" stud with two nuts and a cheater pipe. No washer ... just two nuts threaded on by hand and then tightened against each other with wrenches...

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  • LHC
    replied
    I'm back on the sofa with the laptop for the evening now, so I will try that left hand thread idea tomorrow morning - that never crossed my mind.

    As for the production processes not being standardized - I have come across that in one or two places so far - little taper pins being used where someone else had a straight pin for example.

    Another thought just crossed my mind too - there's an engineering place in town that has an xray inspection setup - I might just show up there with the casting in hand and play the "almost retired guy trying to rebuild a metal lathe for a hobby" card and see if they take pity on me and give it a zap. That would tell me if it's threaded or not ! Then again they might want to charge me a small fortune....doesn't hurt to ask though.

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  • lakeside53
    replied
    Yes, watch out for left hand threads! Yesterday I had to remove the knuckle ends from 12 awg shear actuator arms. The owner had soaked them in gallons of penetrating oil, heated, cooled and beat the crap out of them... no go.

    A little investigation and I could see the threads; sure enough... a quick whack "the wrong way" and they unscrewed. lol...

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  • Don Young
    replied
    Even if others have lathes with the stud screwed in, do not be surprised if yours is pressed (or has left hand threads). Manufacturers in those days tended to not have their processes standardized as well as they do today and repairs sometimes change things.

    I would definitely first try straightening the stud, clamping the casting for safety against breakage. If I had to remove it without damaging the casting I would carefully cut it off and progressively drill it out. When the remains get thin enough you can pick out the remains, whether threaded or pressed.

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  • Bob Fisher
    replied
    Now that I see the pic, I can see that you cannot determine if it is threaded. Good thought on the left hand tread though. Can you see the other end of the stud? Might be some evidence of a thread, right or left. Let us know what works. Bob.

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  • Bill McLeod
    replied
    some studs are left hand on the bottom half

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  • LHC
    replied
    Update - washer between the nuts didn't work - buddy thinks he has some Kroil and is digging for it, otherwise I'll order some.

    Might get to try the heat/cool later tonight.

    Here's a pic of the offending piece - This is on the corner of the saddle casting for the lathe carriage. The casting had been dropped (I have inspected it carefully with a loupe and a buddy is doing a dye test on it Monday). This post is bent slightly but it's hard to see at this angle. The base of this post and the post looks to be all one turned piece and I am told by others with the same lathe that theirs was screwed into a tapped hole in the casting, not screwed in.

    Will update more as I move along (hopefully moving forward)

    Lewis

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  • Bob Fisher
    replied
    KROIL! And maybe some heat, then more Kroil. Bob.

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  • LHC
    replied
    Hi -
    Just got back to the house and I am being told "we're going to the mall" - WTF?

    Anyway, I'll try that washer between the nuts later.

    The machine I am working on is a lathe - a charming old Raglan 5" from jolly England, and chatting with some fellows on the yahoo raglan group, one has told me his has been apart before and it was threaded - so I am just assuming they all are.

    However - I cannot see the start of threads. I will re-check with the trusty Princess Auto 2 dollar loupe again though

    Stay tuned....hopefully I'll have some quality time with the machine later.....after the mall....

    Cheers,
    Lewis

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  • duckman
    replied
    Why is it nobody remembers to put a washer between the nuts when your trying to remove a stud, 2 nuts won't lock.

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  • Mcgyver
    replied
    Originally posted by Bob Fisher
    Are you sure it is threaded into the base?
    that was kind of nagging me as well...you say you've done some research; how sure are you and can you see the start of the threads?

    on the Whitworth, since you're here there's a very good chance you have a lathe. If so, Whitworth are no more difficult to cut than regular threads, you'll want some thread wires if you don't have them....but they are not much $$.

    Point being, preserve the stud if possible, but it's no biggy if you can't...what really matters is not messing up the casting.....you can always make a new stud.

    if none of the ideas presented works, cut it off, drill it out and make new one

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  • Bob Fisher
    replied
    Are you sure it is threaded into the base? You should be able to see some evidence of threads. If so,try some Kroil, it is the best penetrating stuff I have ever used. I would use vise grips on it if is is threaded. BIG vise grips. Bob.

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  • Willy
    replied
    That cam stud remover is something I never knew about and seeing how it works is interesting. The first thought that came to mind though - is there a chance of damaging the smooth OD of the stud with the three cams if you are really coming aboard it?
    It all depends on how tight the stud is into the casting and how hard the stud's material is. If the stud's material is hard enough to resist deformation due to the removal process it will not leave much evidence of the procedure.
    Whatever you can do to lessen the strain of removal will of course help.
    Back and forth movements, however small will start things moving. Heat, lubricants, vibration will all aid the process.

    Is there a possibility in case of a worst case scenario of replacing the stud with one that does not have Whitworth threads?

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