So for Xmas I treated myself to a rotary table... I didnt want to spend a fortune, but I wanted one that was a bit above the usual nasty chinese and indian ones. So I went over to Chronos and had a look at what they had and decided on this new design Soba 4", a copy of the 4" Vertex. OK its not a Vertex, but is a cut above their usual quality. It has a MT2 central taper so can mount a chuck, or use a centre...
Attachment 1357
One reason I chose it is that its a good candidate (IMHO) for CNCing...
Removiing the handle, reveals a 10mm spindle
Attachment 1359
and removing the vernier collar reveals a usefull 15mm deep by 18mm dia place to clamp a stepper mount to.
Attachment 1360
The plan is simple. Machine a circular collar 14mm thick 34mm OD, 18mmID with two or three 4mm tapped holes for locking grubscrews, to fit over the bearing. Place a 10x18x5.5 thrust washer on the 10mm spindle, drill out a L050 coupling and lock to shaft while using some puller arrangement to pull shaft outwards and rotating table to push shaft out - this will preload the thrust bearing. A 67mm length of 40mm OD, 3mm wall tube forms the basis of the stepper mount. This will locate into a 40mm dia, 8mm deep bored hole in a 10mm piece of aluminium 56mm square drilled out for a NEMA23 motor and counterbored 38.1mm. the tube is retained in the plate by 2 or 4 grubscrews through the sides of the plate. The general idea is shown below:
Attachment 1361