The PM-25 is a great mill, but the one that I received lacks flats on the spindle. All the methods I could think of to perform tool changes, essentially require three hands and then generally one hand gets cut. What is greatly missing is a way to lock the spindle to free the operator hands to insert and tighten the tool.

I looked at commercial spindle locks, but they are expensive and don’t fit the PM-25, so I made one. I wanted to preserve the belt drive and belt guard, so much of the spindle lock was installed inside of the mill head. The spindle lock was a big improvement to the Precision Matthews PM25MV milling machine to safely and quickly change the tool.

I made a video describing the spindle lock, have a look if you are interested. Use of the spindle lock is compared to other methods of changing the tool. Faster tools changes greatly improves the productivity of the CNC conversion.

The spindle lock was designed in SolidWorks and CAM was developed in Fusion360.

The spindle lock is one of the most useful changes I’ve made to my PM-25 mill. It ranks along side the CNC modifications. I wish it would be a standard feature on an otherwise great mill.