CNC Joint Collars
First, watch this video to see how the cueball collar bodies are defined, bored & threaded. The pictures below are a follow-up showing how the collars are finished. Then, watch this video to see how a Juma joint collar is machined in real time. Instead of doing 3 at a time like with the cueball, I use a vertical 5C collet holder with a positive stop to hold the blanks. I machine all the bores first, then change the cutter & thread them all.
The CNC'd cueball is band sawed to remove the individual collars for further machining.
This simple Delrin arbor is machined with 5/8-18 x 11/16 threads. Each of the collars will be screwed on & get the OD machined to .875" diameter.
One of the collars is shown installed & being machined in these two pictures.
Here is a comparison of the finish machined cueball joint collars and commercially available SS joint collars. The only difference between them is that I machine a locating diameter at each end of the collars vs. the single .500" diameter at the joint face of the SS collars. The Delrin arbor is also shown.
Finally, a forearm with trim rings installed, ready for the joint collar. The register diameters show how the accurate location of a joint collar is achieved. FWIW, this collar happens to be made of Juma.
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On a related issue, a customer wanted a cueball buttcap. I realized I could get the buttcap & still have room for 3 ferrules. Here is the cueball with everything threaded & ready to be sawn out.