Pocket NC 4 jaw chuck workholding

Workholding on the Pocket NC is still, well, a work in progress for me, and it is for many people.  There aren’t a lot of off the shelf solutions.  The machine does come with a mini-vise, which can hold a surprising amount, but it has some limitations.  For one, it isn’t referenced to the axis of rotation of the B axis.  Another, anything held in it can often be far away from the furthest Z travel available, resulting in the need to use extended reach tooling.

Enter, once again, Ed Kramer @ekramer3 on IG, who came up with a solution consisting of strictly off the shelf parts that results in a 4 jaw chuck being placed about 1.75in off the surface of the B axis plate.  This can hold round stock out to 70mm.

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Found a workable mounting solution for the Sherline 4-jaw chuck. Shars ER16 straight shank toolholder has the correct M22x1.5 threads to mate to the hub on the chuck. Time to get busy with some larger stock on the @pocket_nc V2-50. EDIT: For other PNC owners who might be interested in this setup, here are the components I used. From top down: Sherline 4-jaw chuck with ER16 hub (part # 1078). Or part # 1042 if you prefer a 3-jaw chuck. Shars ER16 straight shank collet chuck toolholder (part # 202-1423). Any brand will do, just make sure it is threaded for a M22 x 1.5 collet nut, M19 threads won’t mate with the 4-jaw. All held in a 3/4” ER40 collet using Pocket NC’s ER40 fixture. Your straight shank toolholder may have a different shank diameter so select the correct ER40 collet that fits your particular shank. . #instamachinist #cnc #cncmachining #cncmachinist #cncmilling #cncmill #milling #machinist #digitalfabrication #maker #desktopmachine #desktopmachining #desktopmachinist #pocketnc #pocketncv2 #pocketncv2_50 #fusion360 #makersgonnamake #mindmadewithcnc #mindmade #5axis

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In case Instagram forgets itself, the relevant parts are:

A few pictures of my setup:



And here is a short video of it cutting:

Finally, if it is of use to anyone, this is my F360 file containing the fixture.  Bewarned, it is hard-coded to my V2-50’s B-table offset as calibrated by PocketNC.