Gallery, Projects and General > How do I?? |
Remove Seized on chuck ?? |
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Manxmodder:
--- Quote from: awemawson on June 05, 2014, 05:55:49 AM ---Mick, I do have a 1" drive air operated impact driver you could use if you have a big enough air source - I run it off a road compressor. Big hex in chuck and suitable socket should eventually shift it. (Got it for various big bolts on farm machinery) I still think that a heavy reverse interupted cut would do it --- End quote --- Hi Andrew, as I said earlier my real concern with this approach being that the threads may have picked up and galled. Any forced effort to fully unscrew the backplate off could do dreadful damage to the spindle thread. If Mick can get the backplate to undo just enough to be clear of the register shoulder and it is still tight to turn then it will be safe to assume the thread has picked up and galled and unscrewing it any further will only do more harm.....OZ. |
awemawson:
I'm just glad I've never owned a lathe with a threaded spindle mount. Only had L0 and D1-4 on manual lathes which don't potentially present this problem. |
Manxmodder:
Andrew, I absolutely agree with you,threaded spindles are the devil's work. The worst of it being that Harrison offered the threaded nose as an option on the L6,the standard fitting being L00. When Mick was doing the L5 restoration thread I did suggest that converting the threaded nose to taper fitting by means of an adaptor was something I plan to do to mine. Seeing Mick's current predicament has further convinced me that a taper conversion is the way forward for me....OZ. |
Fergus OMore:
Thinking of Tapers(Oz!) is there room to put in a wafer thin pair of taper wedges to marginally jump the threads onto another part of the thread and break or alter the galling. It is classic engineering where the crests of the threads are probably too high. and adding to the jam. It does reshape the threads -a tiny bit thinning them. OK, it is hardly a time to lecture about the rounded crests and whatever they should be but it has been written about by others more expert than me. |
vtsteam:
Oz, I think that's right, it couldn't be wringing force because unscrewing would put it in shear, where it is weakest. Likewise I don't think it's any kind of suction force because of the same way it is being attacked -- suction can only be 14.7 lbs/sq in, which isn't much whe figuring the area involved, and it's oriented the wrong way to resist turning -- just like a suction cup on oiled glass -- you can slide it sideways relatively easily. And in addition, the threads apply mechanical advantage to breaking the seal in the axial direction -- plus the advantage of a 3 foot bar Mick used as a lever. I don't think its suction or wringing. That leaves galling in either register or threads as the only other possibilities. Since it went on easily, was oiled and cleaned, and wasn't tightened hard or worked while turning, the most likely problem is that something jammed in those areas that wasn't seen or felt, and did not inhibit screwing the chuck on, but only acted when trying to remove it. For that mysterious circumstance, I can imagine a piece of thread with a crack in it, maybe in the backplate, not being noticed and staying in place when the chuck was screwed on. That would explain the ease. But then when unscrewing the thread piece is forced outwards and jams, like a latch lock. As more unscrewing pressure is applied the thread piece, being relatively soft, deforms in length, increases in width and becomes more like a plug. Expanding and locking the thread further with every increase in force. That's about all I can think of considering the conditions things started with -- which would seem to have been ideal. |
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