Some measurements from the Jet JDP-17
Before ordering a shaft collar, I thought I'd better take some measurements on the Jet drill press and here's what I came up with (see attached). The sheet makes more sense with these additional notes:
The factory quill is a 16mm steel shaft threaded M16-2.0; the case of the drill press head is pretty close to the quill; there's a nut on a bolt mounted in the case, behind the quill, that closes the distance even more.
The two existing nuts and washer that are Jet's way of providing a quill stop are only 23.78mm in diameter. The quick-release 16mm shaft collar in the Zoro's catalog has a published O.D. of 38mm. So there is a real question of clearance.
The critical measurement would seem to be the narrowest distance between the outside edge of the quill and any point on the nut. With that measurement in hand, and knowing the radius of the quill and the prospective collar, what I came up with is a clearance of 0.5mm - more than a blond hair but less than a brown hair, one might say. If it came down to it, I think I could dress an interfering corner of the nut a little bit with a file, enough to allow the collar to be threaded on and used.
At this point, it looks like the only thing to think about is whether the hinged arm of the collar is going to be more trouble than it's worth: an Allen set screw might be easier to deal with, particularly with a handled wrench. In order to get a tight grip on the shaft, the locking arm might be a tough customer to snap and unsnap repeatedly with arthritic fingers. I've already got some of those and a set of handled Allen wrenches. Not to mention the difference in price. Have to think about it.
If anyone sees a flaw in my measurements or has some experience with snap-locking shaft collars, sing out and loud, before I add something to my Zoro's cart!
In the land of the blind, the one-eyed man is king.