View Full Version : 4th Axis Work Holding For Rectangular Work

14-09-2016, 10:38 AM
I have a part which I manually machine which I'm developing a CNC strategy for, I want to machine from rectangular stock and I needed the stock to be quickly, easily and repeatably mounted on the 4th in the mill with maximum ease and minimum waste of time and preferably stock.
My first solution was to centre drill both ends of the stock and turn a round boss on one end to mount in the chuck, a jig for drilling the ends worked great but turning the boss was an extra op I didn't really want or need.
I considered swapping the 3-jaw on the 4th axis for a 4-jaw but that still seemed a less than optimal solution, so I parked it for a week and carried on with other things whilst I cogitated further.
These end-cap fixtures are what I came up with


They worked perfectly on the test part (the middle one of the three shiny bits ;-) )


so I'm going to machine a batch of fixtures, a spherical surface on the boss might be nice.

The stock mounting procedure is now;
Cut stock off square
De-Burr ends
Knock a fixture on each end and add a drop of Bearing Fit to each corner
Throw it on the mill once the Bearing fit has set