I'm sure there are a few other ways to figure out how thick a spacer (a single is better than a shim stack) needs to be to fix the short arbor problem. I've done a few myself and the fastest / easiest way I've found is to start too thick and reduce until you have the endshake you want. When dealing in thousandths, it's obviously easier to sneak up on it rather than spending a lot of time trying to get close to start with.
The head of a #12 pan head sheet metal screw (belt pistols) or a #14 (for horse pistols) is too thick and can easily and quickly be sanded down to get your specific thickness. If you have a drill motor and a belt sander it only takes a few minutes. Remove the shaft of the screw and you all the material needed to make an excellent spacer. The round head of the pan head makes good contact with the cone shaped end of the drilled arbor hole and is "self centering". I generally get the clearance down to .004"/.005" and then dress the end of the arbor down to get to .0025" - .003". This method can/will increase the wedge slot slightly which is why I always install (in the end of the arbor into the wedge slot) a 1/4 X 28 set screw that has been ground smooth and polished for an adjustable wedge bearing. It not only restores the slot size, it allows you to adjust for any wedge wear as well as wedge placement (how far it inserts) for appearance preference or holstering interference.
As far as the 90° "test" goes, the idea is to have as little clearance as possible between the arbor and the arbor hole. Removing material just to be able to do the test (in my opinion) is more destructive than constructive. The broaching process for the arbor slot upsets material in a manner that causes the twisting of the barrel on the arbor impossible without cleanup. It's more of a "keyed" fit and allows the two assemblies to mate only when aligned (thus the test isn't a reliable method without material removal). You can clean up the arbor to ease removal /installation but there's no real need to go further just for the sake of performing a particular test. A simple small washer in the arbor hole followed by re-assembly is infallible proof of a short arbor . . . with no destruction of the arbor.
Mike
The head of a #12 pan head sheet metal screw (belt pistols) or a #14 (for horse pistols) is too thick and can easily and quickly be sanded down to get your specific thickness. If you have a drill motor and a belt sander it only takes a few minutes. Remove the shaft of the screw and you all the material needed to make an excellent spacer. The round head of the pan head makes good contact with the cone shaped end of the drilled arbor hole and is "self centering". I generally get the clearance down to .004"/.005" and then dress the end of the arbor down to get to .0025" - .003". This method can/will increase the wedge slot slightly which is why I always install (in the end of the arbor into the wedge slot) a 1/4 X 28 set screw that has been ground smooth and polished for an adjustable wedge bearing. It not only restores the slot size, it allows you to adjust for any wedge wear as well as wedge placement (how far it inserts) for appearance preference or holstering interference.
As far as the 90° "test" goes, the idea is to have as little clearance as possible between the arbor and the arbor hole. Removing material just to be able to do the test (in my opinion) is more destructive than constructive. The broaching process for the arbor slot upsets material in a manner that causes the twisting of the barrel on the arbor impossible without cleanup. It's more of a "keyed" fit and allows the two assemblies to mate only when aligned (thus the test isn't a reliable method without material removal). You can clean up the arbor to ease removal /installation but there's no real need to go further just for the sake of performing a particular test. A simple small washer in the arbor hole followed by re-assembly is infallible proof of a short arbor . . . with no destruction of the arbor.
Mike
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