Brush Deburring System

Patented Technology for Deburring and Finishing Mica Undercutting Eliminates Hours of Hand Finishing Work



One of the unique benefits of using a CAM Undercutter is the ability to use our patented Brush Deburring System to speed your undercut commutator finishing process.

Brush Deburring Technology was developed by CAM in conjunction with the manufacturers of traction motors to eliminate the tedious and imprecise hand chamfering of the copper bars to produce a small radius on the bar's edges.

Just a few minutes of brush deburring removes the burrs, cleans the commutator, and rounds the edges of every bar.


Why is Brush Deburring Better than Hand Chamfering?

Brush Deburring maintains the bar width. When you use V-cut chamfering saws or hand tools to modify the bar edge you are also decreasing the width of the bar. This decreases the contact surface area between the motor's brushes and the bar.

Brush Deburring is consistent and controllable. Unlike hand work, brush deburring produces repeatable results every time. All of the burrs are removed and each bar receives the same amount of corner radius.

Brush Deburring is FAST! It only takes 15 minutes to deburr and finish a traction motor sized armature with Brush Deburring. In comparison, hand chamfering often requires several hours of manual labor.

Brush Deburring is clean. It does not create any chips that can fall into the slot or create a secondary sharp edge like any cutting tool will.


Brush Deburring is available on:

  • MDU Automatic Undercutters
  • HDU Heavy Duty Automatic Undercutters
  • CU Automatic Lathe Undercutters
  • UL Lathe Undercutters
  • RF Automatic Undercutters
  • JHT Universal Commutator Turn & Undercut Machines
  • JH Universal Commutator Turn & Undercut Machines
  • DJ Universal Armature Machines
  • DJM Universal Armature Machines

How it Works

Brush Bristle deflection by opposed contact during rotation removes burrs from one side of the undercut mica slot. By reversing direction, the burr is removed from the opposite side of the bar.


Traditional Commutator Deburring and Chamfering is labor intensive and inconsistent.

All DC motor OEM undercutting specifications require deburring of commutator bars and elimination of sharp edges on the copper bars caused by cutting tools.

Over the years various methods have been used to perform this work including; hand scraping using a modified hack saw blade, pulling a V-tool thru each slot by hand or, a combination of hand work combined with special V-cutting saw blade on the undercutter's spindle. These techniques have several common attributes:
  • All of these methods are imprecise, tedious and time consuming to perform.
  • All of these methods create more sharp edges and affect motor brush contact with the commutator
  • All of these methods decrease the surface area of the copper bars and change the commutator's electrical properties
  • All of these methods can lead to carbon build-up in the mica slot, causing electrical shorting between the bars
  • All of these methods are performed by shops without CAM Undercutters

CAM's Exclusive Brush Deburring is the Better Way!

CAM's patented Brush Deburring System - works with any CAM manufactured Undercutter using proper, high quality carbide saws. It provides consistent results, is easy to perform and takes only a few minutes to do.

Special Brushes do the work! The bristles of the deburring brushes are impregnated with silicone carbide which is non-conductive so the dust created by deburring won't cause electrical shorts. the brushes come in three different grits (120, 180, and 320) based on the thickness of the mica. After Brush Deburring, the commutator surface can be polished with paper, stone, diamond turned or grounded.

A light touch is all you need. The operator moves the brush back and forth across the surface of the commutator as the armature and the brush are rotated in the same direction. The direction of the rotation is reversed and the process is repeated to put a small radius on the other edge of the commutator bars. The entire process only takes a few short minutes of rotation in each direction. Contact pressure of the brush to the commutator is typically between 0.012" to 0.015"

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