A clamp for rotary tables
Alignment can be a thing that is annoying
Some time ago, a rotary table was purchased with the intention of producing accurate and attractive graduated dials for the various electronics projects. Initial attempts proved problematic though. When a work pece is mounted in a mill, there are 2 dimentions to worry about, X and Y. these are aligned on the XY table by whatever means is best and the milling can then commence. If a rotaty table is added to this the situation becomes rather more complex due to the need to align the work pece withthe center of the rotary table and the rotary table with the spindel center. If for example one wanted to mill two grooves on a flat disk, 90 degrees apart, such that they met exactly at the center point, one would have to align the spindle center exactly with the center of rotation of the rotary table and align the disk center witht he center of the rotary table. the grooves could then be performed with one axis of the XY, and the rotary axis of the rotary table.
On a large mill this can be performed with lever gauges and other alignment tools, but on a very small mill it becomes more of a problem. A easy mounting solution was therefore required. After some thought, a partial solution was reached. the Rotary table has a 2MT taper in the centre. a 2MT arbour blank was purchased cheaply from ebay and machined into a cone point. the centre was drilled and (very carefully) tapped. disks needing to be machined, can (assuming they have a centre hole of suitable diameter) be fitted over the cone, and clamped down onto it with the aid of suitable spacers, washers and a bolt into the centre hole. the arbour blank already had a tapped rear shaft, which is bolted from the under side of the rotary table such that it is held tight in place.
I have used this successfully to make a very nice dial for a high voltage power supply and will use it on the signal generator shown elsewhere in this site at some point as well. Unfortunately it remains a partial solution as it does not assist with aligning the centre of rotation of the rotary table with the spindle centre. Any further developments will be documented here so stay tuned for a solution to this second problem.