Mounting a high speed spindle to the quill?

[Sparky_NY]

Bad idea?

I have seen many high speed spindles mounted to the quill of a bridgeport with a clamping type bracket. I am about to do the same but wonder if there is any rotational play in the quill? Naturally, any play there would allow the outboard high speed spindle to rotate also, not a good thing!

I have seen many of those 90 degree drive units for a bridgeport that I believe also clamp to the quill. I assume any rotational play there would be bad for the same reasons.

The bridgeport is a V2E3 cnc, which is pretty much a standard 2J head but there is no quill locking device and I will be using the quill Z downfeed for the high speed spindle also, so the quill must be able to extend/retract.

[TRX]

Make a ring to clamp around the quill. Run an arm over to some convenient place on the head or column and attach it however seems convenient.

[Sparky_NY]

Make a ring to clamp around the quill. Run an arm over to some convenient place on the head or column and attach it however seems convenient.

The quill has to extend/retract just like when a normal tool is mounted. The spindle would just be offset from the main spindle. A 'arm" would interfere with the motion. I have seen one that used a vertical rod with a thompson ball bushing for stability but that one was not clamped to the quill.

I am looking at the standard common way you see DIY spindles mounted by clamping to the quill.

I have since found that it is the vertical groove in the housing front (the one that has the depth stop ring on a manual mill) that prevents rotation of the quill together with the 3/8 bolt in that groove. The cnc head does not have a depth stop ring but a rectangular plate in that groove that trips the limits. From what I read, that plate is a pretty good fit with minimimal slop.