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  1. #76
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    Quote Originally Posted by Sterob View Post
    ......
    No-ones mentioned it for this. Maybe they don't WANT me to witness them work. I can understand that. lol
    I guess it depends on what they are doing. My orthopod didn't want me to watch getting my hip replaced - although I asked to. He said " we generally do intrathecal but put the patient to sleep. It gives a better outcome than general anaesthetic. But we have to put you in unpleasant positions that you may not tolerate awake"....
    I had internal bladder surgery twice fully awake and once with (accidentally administered) la la land injection - medazolam, because "that was the usual protocol" without asking me....
    I remember only a little of that event but I was amazed and very awake for the other two. Bloody brilliant technology at work! They even set up a separate screen for me to see comfortably, once they were convinced I wasn't going to faint or chicken out. The surgeon was great: kept me included in the conversations and explained and showed me stuff. They were amused how fascinated I was to have a "deep look" at my insides lol.....

    Cheers
    Joe
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  2. #77
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    How's this for an idea? Maybe you can use it to illustrate the idea.... or make one?
    Obviously the dimensions are guessed based on your photos....
    Submitted in good humor - I just like fiddling with ideas....

    Pin Spanner assembly.jpg
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  3. #78
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    Quote Originally Posted by Jekyll and Hyde View Post
    I've got no new ideas on the actual removal unfortunately, but I'm pondering the possible vibration/resonance issue. Given you have a bit sticking out, I wonder if it would be possible to do something to damp or alter vibrations should they prove to be a problem?

    Not by any means an area of expertise for me, but a couple of thoughts I had:

    One was a pair of narrow panelbeaters type leather bags filled with lead shot - one under, and one on top. Probably won't do a whole lot, but may take the edge off?

    Or possibly something a bit like the things hanging off the bottom of my diesel Land Rover that are supposed to arrest certain vibrations - they appear to be nothing more than a steel plate bracket attached to driveline parts, with big lumps of cast iron attached to said bracket by means of vulcanised rubber. Maybe it's possible to clamp something designed along that idea to the protruding part (maybe via something as simple as a hoseclamp) to at least try and pick off some of the harmonics of it?

    Finding the right weights/positions etc to target the specific frequency is of course the big fault here, and it may well be completely unviable, but thought I'd throw it out there in case it sparks an idea with someone else.

    Thanks!
    I don't think it will be needed if we are only drilling` 2mm holes.....Only way to find out for sure is to do and see.....

  4. #79
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    Quote Originally Posted by jhovel View Post
    How's this for an idea? Maybe you can use it to illustrate the idea.... or make one?
    Obviously the dimensions are guessed based on your photos....
    Submitted in good humor - I just like fiddling with ideas....

    Pin Spanner assembly.jpg

    Looks good Joe.
    I like the centre pin to locate the tool.
    The biggest problem ( for ANY tool, not just yours ) is the accurate drilling of the holes in the Bushing.

    I might draw up a template in paper, cut it out and glue it to the end of the Bushing as a guide for (painful ) centre popping.Thats going to be the worst part.....

  5. #80
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    Could you dremel your centre points instead of punching them? Might be a bit less unpleasant...

  6. #81
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    or use a spotting drill directly. It would have to be a sharp 4-facet and probably cobalt (M42) or carbide.
    I would hesitate centre punching too! It'd be worse than hitting your shinbone on a towbar I imagine....
    Out of curiosity, what sort of forces can the osteointegration transmit? And also, how sensitive is the transmission of small impacts? I can't even imagine vaguely how it compares to the impact transmission through joint cartilage layers to bone in mine - or indeed your other leg. You have a direct comparison that the rest of us don't have..... My hip socket and ball is the same principle, metal in bone, but it feels no different at all, because of the intervening joints in foot and knee, and the metal joint is in the original joint capsule and protected by bursa and muscle from lateral impact.... I'm guessing there is shock absorption in the prothesis to make up for the lack of interface?
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  7. #82
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    Really????
    How hard is it to drill the head off a bolt????
    How hot would it get, if you are worried about that do it incrementally.
    If you used a drilling guide you can also have it made to stop drilling at the depth required
    Any small vibration would be absorbed by the vice, you need to hold the thing, how do you walk on the thing if you cant have a little vibration?

  8. #83
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    Hi Guys,

    Actually that occurred to me last night ! If the head was drilled off, would there be enough of it left to be able to grip it and unscrew the stub. The same would apply if the head sheared off. From the damage to the hex it makes me wonder just how hard that bolt is.
    Best Regards:
    Baron J.

  9. #84
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    Quote Originally Posted by elanjacobs View Post
    Could you dremel your centre points instead of punching them? Might be a bit less unpleasant...

    Wouldn't be accurate enough. Would have to use a stencil and centre pop them.

    Maybe I can hold a large metal weight against the back of the Ambutment to absorb the centre popping...dunno.

  10. #85
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    Quote Originally Posted by jhovel View Post
    or use a spotting drill directly. It would have to be a sharp 4-facet and probably cobalt (M42) or carbide.
    I would hesitate centre punching too! It'd be worse than hitting your shinbone on a towbar I imagine....
    Out of curiosity, what sort of forces can the osteointegration transmit? And also, how sensitive is the transmission of small impacts? I can't even imagine vaguely how it compares to the impact transmission through joint cartilage layers to bone in mine - or indeed your other leg. You have a direct comparison that the rest of us don't have..... My hip socket and ball is the same principle, metal in bone, but it feels no different at all, because of the intervening joints in foot and knee, and the metal joint is in the original joint capsule and protected by bursa and muscle from lateral impact.... I'm guessing there is shock absorption in the prothesis to make up for the lack of interface?

    Smooth transition of force , even quite high force is fine. Walking produces small jaring that is taken care of my a shock aborber in the ankle. Nothing like a rachet drill would produce.
    If 2 hammer taps allows me to get this screw off, I'm willing to try.

  11. #86
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    Quote Originally Posted by BaronJ View Post
    Hi Guys,

    Actually that occurred to me last night ! If the head was drilled off, would there be enough of it left to be able to grip it and unscrew the stub. The same would apply if the head sheared off. From the damage to the hex it makes me wonder just how hard that bolt is.

    I would think that there would be about 5mm of material to grip if the head is drilled off.

  12. #87
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    The more I think about it the more I like the pin spanner idea.
    I saw this today:

    https://photos.app.goo.gl/zogp297mXo6P8gZN9

    A great idea.

    If we used roll pins, they should not shear. I think if we can drill the holes in the screw it should work.

  13. #88
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    Roll pins are not very strong and will likely bend.
    Steve you have ignored 2 of my posts, i am assuming that this is because i have mentioned using a vice, you need to hold the job securely.
    If you are planning on using a 2mm drill bit in a cordless drill then you are going to need some form of protection as you are likely to be stabbed in the stump with a broken drill bit. Did you know small drill bits break very easilly in hand drills? You need a bit of pressure when drilling stainless or else it will get hot and work harden.
    That stripped hex is your pilot hole, secure the job and use someone experienced with using a drill to drill the head off.
    If you are squeamish about it then bite on a hammer handle...

  14. #89
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    Quote Originally Posted by shedhappens View Post
    Roll pins are not very strong and will likely bend.
    Ok, then I will have to find a better option. I thought they would be quite strong compared to dowel pins.

    Quote Originally Posted by shedhappens View Post
    Steve you have ignored 2 of my posts, i am assuming that this is because i have mentioned using a vice, you need to hold the job securely.
    Not ignored you....just couldn't process how it was going to work......Its not that easy.
    Last time we were in a hospital consulting room, so no vice was close by.
    I doubt the next attempt will in a machine shop( unless something drastic changes) , as such either, so if we were to use a vice it would have to be free to move. ( which they normally aren't)

    Quote Originally Posted by shedhappens View Post
    If you are planning on using a 2mm drill bit in a cordless drill then you are going to need some form of protection as you are likely to be stabbed in the stump with a broken drill bit.
    Did you know small drill bits break very easilly in hand drills? You need a bit of pressure when drilling stainless or else it will get hot and work harden. [/QUOTE]

    I'm confident I could do it but 'I' won't be able to reach to do it, I agree.

    Quote Originally Posted by shedhappens View Post
    That stripped hex is your pilot hole, secure the job and use someone experienced with using a drill to drill the head off.
    I understand. I am trying to weigh up the pro's and con's of drilling two 2mm holes against drilling one ~8mm hole in the centre.
    I suspect my ability to handle the vibrations may be wildly diferent between the two methods, even when using a vice......


    Quote Originally Posted by shedhappens View Post
    If you are squeamish about it then bite on a hammer handle...
    Are you kidding? Do you know how big hammer handles are? I'd never get one in my mouth.....lol
    Sensation is hard to describe. its light fireworks going off behind your eyes......Its like your brain can't process whats happening.Not pleasant.

  15. #90
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    No worries Steve, ultimately it is your decision how to proceed with your bolt of doom... Just on a side note I have very little faith in the medical establishment, sure they have saved my life and also helped me with maladies over the years but they have also nearly killed me, infected me, poisoned me, burnt me, butchered me, misdiagnosed me, mis medicated me, they can be a useless pack of bastards..... Hence why in my opinion a tradesman would be better suited to remove that bolt.

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