Thrust CollarEach Keyseat Miller has a Fitted Thrust Collar- located under the flange of the Driving Spindle. The purpose of the Thrust Collar is to locate the Driving Spindle in the correct position. The correct position of the Driving Spindle allows the Driving Pins (at the bottom of the Driving Spidle) to engage the back of the Cutter tooth properly. 

A Thrust Collar which is too thin will allow the Driving Pins to fall too far into the gullet of the teeth and a Thrust Collar too thick will not allow the Driving Pins deep enough. 

This video shows the Driving Pins engaging the teeth properly- this is what is achieved when the Thrust Collar is fitted correctly. 


Internal Mechanics Video


Question 1 – When do I need to fit a thrust collar?

1. You change Cutter widths.
For example, you change your #3 Keyseat Miller from a ¼” wide- 11 Tooth Cutter to a ⅜” wide- 13 Tooth Cutter.  These Cutters have different widths and also different diameters. A properly Fitted Thrust Collar will raise or lower the Driving Pin placement and allow the Pins to engage the back of the Cutter tooth properly. 

Please Note: If you ordered different widths of Cutters when you originally bought your tool- each Cutter width came with its own Fitted Thrust Collar. 


2. You order a new Driving Spindle.
First, try the original Thrust Collar with the new Driving Spindle- Quite often the old Thrust Collar fits perfectly and can be used with no further effort. But, if the new Driving Spindle does not allow the pins to move correctly- You will need to adjust the thickness of the Thrust Collar to allow this new Driving Spindle to fit your tool.


Question 2 –  How do I fit a thrust collar?

  1. Loosen Set Screw on Brass Nut and then remove Brass Nut
  2. Remove Driving Spindle and original Thrust Collar
  3. Install new width Cutter into Cutter slot
  4. Place new Unfitted Thrust Collar under flange of new Driving Spindle and slide into spindle hole. 
  5. The Driving Pins will probably be riding high over the Cutter teeth. In order to get the pins down to achieve a good fit- it will be necessary to reduce the thickness of the Thrust Collar. Reducing the thickness can be done on a surface grinder or a lathe and may need to be reduced in varying stages to arrive at the correct thickness. 
  6. Flame harden and quench in oil.
  7. Re-assemble: Driving Spindle, Thrust Collar, Brass Nut and Set Screw


Please call with any questions 513-541-6682. We love to hear from our customers and as always, Thank you for using the Keyseat Miller