Modifying a Milling Cutter for More Clearance

Copyright 2009 by James P. Riser

This is the problem that I want to avoid


This buildup of wax is caused by the cutter shaft rubbing on the wax being machined. The wax heats up and sticks to the cutter shaft. This web page demonstrates how I solve this problem by grinding some cutter clearance.

The first things to remember are that the solid carbide cutters are hard and brittle. They must be carefully and gently ground with a diamond wheel. In this example I am using .060" ball cutters with a 1/8" shaft diameter. They will be used for a project on my Roland MDX-20 which requires a lot of side clearance.


This is what a standard extended length cutter

and a regular length cutter look like.



My goal is to create my own extended length cutter from a cheaper and on-hand regular length cutter. Being able to do so will allow me to avoid having to order a special cutter and waiting for its arrival. I detest down time.

To do so I will be using my Gorton 375 cutter grinder. This grinder was originally made for grinding single lip cutters and end mills. It will work well for this task. Yes, I grind outside - due to flying grit.


This grinder allows precise angle/feed control.


The collet and mounted cutter.


The wheel is a diamond impregnated wheel for carbide grinding.


The cutter is positioned ready for grinding.


The grinding begins...


The feed into the grinding wheel is controlled by this handle.


Almost there and done.


The goal was to get the shaft just slightly smaller in diameter than the .060" ball end.


The reading on the dial was noted.


Being greedy, I wanted even more clearance.


To squeeze out all of the clearance possible, I set the angle to 10 degrees.


This allowed a bevel and additional clearance.


The top cutter is the one that I just ground.

The bottom cutter is as bought new.

This technique will certainly meet my needs.


Too often I have needed a special cutter on a weekend when one could not even be ordered. Too often I have needed a cutter with just a bit more clearance. This technique solves both of these problems.

This same technique may be used with a watchmakers lathe having a milling or grinding attachment.