THE SHOP, INC. - Clipper Blade Sharpening Machines and Precision Lapping Discs

 

Clipper Blade Lapping Disc Surface Structure

 

This article is written to explain how the accuracy and surface finish of an aluminum clipper blade lapping disc plays a part in the performance and longevity of the disc. This is the basis for all discs regardless of the diameter or angle of cut.

Presently there are two distinctly different surface structures for aluminum lapping discs.

The first and most commonly used is lathe machined using a single pointed tool bit that leaves a coarse or fine spiral groove patterned surface. The second is also lathe machined but is then followed by a scraping procedure that completely removes the spiral lathe pattern leaving a uniform and dense surface.

Lathe machining has only economic benefits and comes with risks. Although both manual and CNC lathes have the ability to make the cutting tool bit travel in a very accurate path, they cannot control what is happening to the very tip of the tool bit, thus the surface finish and accuracy may vary in depth and texture.

Surface Texture

Lathe Cut Surface

Lathe Cut Surface


Lathe Cut Surface Wear Pattern

Lathe Cut Surface Wear Pattern

Scraped Surface

Scraped Surface


Scraped Surface Wear Pattern

Scraped Surface Wear Pattern

There are special tool bit coatings and coolants that help in keeping the cutting tip in good form but aluminum is very susceptible to build up on the tip of the tool bit, due to the cutting pressure and heat. This ever changing build up, along with normal cutter wear, varies the depth of cut and the shape of the grooves while traveling the long distance across the lapping band. This leaves a surface structure for clipper blade sharpening that is varied in strength, allowing high and low patterns to develop with the introduction of the abrasive aluminum oxide grit. How fast the weaker areas erode determines the useful life of the surface. A common remark in the industry is that you sharpen in the "sweet spot" just before lifting the blade off, meaning there are good and bad areas of the surface.

The correct lapping procedures when sharpening clipper blades should slowly create a uniform, non-wavy, dished wear pattern that is low only in the center of the lapping band and high on each edge. Since the center area of the lapping band is constantly being overlapped by the blades whereas the inner and outer edges are not, it wears down sooner. This represents that the surface was accurate and of equal strength to begin with. Very seldom does this occur with lathe machining alone. To help compensate for the variances of a lathe cut surface, a wide lapping band is needed along with a swift stroking action.

As a result of the lathing process with its variances in surface structure, the useful life of clipper blade lapping discs vary greatly and has been a major concern of the professional sharpener from the beginnings of this industry.

The second procedure, where scraping is employed, removes the varied spiral grooves left from the lathe machining and restructures the surface with a one piece precision ground tool which spans the whole width of the honing band, thus producing a solid dense unvaried mirror like surface. This surface when used properly will not only wear evenly, but will grind more steel per square inch and last longer than a lathe cut surface.

We scrape all our discs to maximize and verify the accuracy and even density of the surface, thus increasing the useful life of the disc.

For more information, watch the following video:


Disc Surface Structure [05:22]