Emco Unimat 3 Milling Column rotational locking clamp

This simple clamp allows the Unimat 3 milling column spindle to be locked from rotating, thus allowing the placement of a digital indicator or dial indicator in the Jacobs chuck. Using the leadscrew handwheel, cross slide and vertical fine feed, the tip of the indicator can then be made to traverse a surface and readings taken to produce a set of coordinates (contour map) for importation into a CAD program.

The clamp can be printed from any type of filament, PLA is fine. The tightening screw bore fits the standard M5 allen bolt and nut that is common on Unimat accessories, such as the milling table clamps, and can be temporarily borrowed to use in this situation. The two bolts are the regular ones normally fitted to the column for the motor assembly.

Shown is the digital indicator set up to profile the shape of a keyboard key from a vintage DEC VT100 computer terminal. The leadscrew travel is recorded from corner to corner along with the indicator value along the item, when complete the milling column is moved up 1mm and the process repeated.

NOTE
My generic Golden Dragon digital indicator arrived off eBay with a plain flat backplate instead of the fixing eye backplate I had assumed it would be fitted with. Thankfully another thing (https://www.thingiverse.com/thing:1332174) solved that problem. A Unimat tee bolt and nut goes through the eye and allows clamping in the chuck.