Loose key in rear axle

John Carlton, I've been in discussions about whether to put the new keyway before or after the original . I do agree with not putting it 180 but have no real engineering proof. It just doesn't seem the thing to do.
 
john charlton said:
My local machine shop in England recuts a new keyway 130 degrees away from the original . He says NEVER cut a new keyway 180 degrees away .

John in sunny Chandler AZ but maybe some rain on Friday !!!
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I would be interested to know the rationale behind that. Doubtless they have theirs just as I have the "filler piece" suggestion earlier.

One has to admit a lot of "engineering" (and repair) is "gut feel."

Joe K
 
Draw it out to scale. Then notice how thin the cross section is from one corner of the key to the other 180 degrees apart. If the two keys are 90 or so degrees apart there is a much thicker section left on one side. The debate comes in do you want the thick section before or after the new key.
 
Is there a company that rebuilds the axles? By welding up the taper and threads and re machining them?
 
Machine tapers can be grouped into self-holding and self-releasing classes. With self-holding tapers, the male and female wedge together and bind to each other to the extent that the forces of drilling can be resisted without a drawbar, and the tool will stay in the spindle when idle. It is driven out with a wedge when a tool change is needed. Morse and Jacobs tapers are an example of the self-holding variety. With self-releasing tapers, the male will not stick in the female without a drawbar holding it there. However, with good drawbar force, it is very solidly immobile. NMTB/CAT, BT and HSK are examples of the self-releasing variety.

For light loads (such as encountered by a lathe tailstock or a drill press), tools with self-holding tapers are simply slipped onto or into the spindle; the pressure of the spindle against the workpiece drives the tapered shank tightly into the tapered hole. The friction across the entire surface area of the interface provides a large amount of torque transmission, so that splines or keys are not required.

For use with heavy loads (such as encountered by a milling machine spindle), there is usually a key to prevent rotation and/or a threaded section, which is engaged by a drawbar that engages either the threads or the head of a pull stud that is screwed into them. The drawbar is then tightened, drawing the shank firmly into the spindle. The draw-bar is important on milling machines as the transverse force component would otherwise cause the tool to wobble out of the taper.
 
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