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Thread: Delicate engineering problem
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17th Nov 2020, 07:24 PM #76
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
JoeCheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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17th Nov 2020, 09:16 PM #77
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.jpgCheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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17th Nov 2020, 09:48 PM #78Diamond Member
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17th Nov 2020, 09:53 PM #79Diamond Member
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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.....
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17th Nov 2020, 09:55 PM #80Gear expert in training
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Could you dremel your centre points instead of punching them? Might be a bit less unpleasant...
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18th Nov 2020, 02:41 AM #81
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....
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18th Nov 2020, 09:21 AM #82Most Valued Member
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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?
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18th Nov 2020, 08:08 PM #83
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.
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18th Nov 2020, 11:07 PM #84Diamond Member
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18th Nov 2020, 11:10 PM #85Diamond Member
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18th Nov 2020, 11:14 PM #86Diamond Member
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18th Nov 2020, 11:19 PM #87Diamond Member
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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.
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19th Nov 2020, 08:26 AM #88Most Valued Member
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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...
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19th Nov 2020, 01:45 PM #89Diamond Member
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Ok, then I will have to find a better option. I thought they would be quite strong compared to dowel pins.
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)
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.
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......
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.
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19th Nov 2020, 02:42 PM #90Most Valued Member
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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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