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  • Writer's pictureThe Sharpener

SPEEDING UP AND IMPROVING SHARPENING CHISELS WITH MICRO-BEVEL

THIS IS MY PREFERED METHOD TO SHARPEN CHISELS


Sharpening a chisel the traditional old fashioned way involves honing the entire surface area of both the bevel and the back. There is absolutely nothing wrong with sharpening a blade in this fashion, but it has drawbacks. - Honing the whole bevel area to a high quality takes time and is only straightforward if you guide the blade precisely during sharpening. This is quite a feat if you sharpen freehand and sometimes things go wrong (e.g., you fail to pick up the whole cutting edge). - When honing the back, you can remove only a very thin layer – because of the large area and the fine stone. You are unlikely to remove deeper scratches, caused perhaps by errant coarse grains. These scratches will increase in number and will form tiny notches if they continue to the cutting edge. If you want a truly perfect cutting edge you will either have to spend a lot of time honing the back or remove these scratches thoroughly from time to time, and that involves regrinding and then again honing the back.


YOU CAN AVOID THIS LABORIOUS PROCESS: Regardless of the length and thickness of the blade, the actual cutting process takes place right in front, at the cutting edge. In other words, it is enough if only there (i.e. over the first tenths of a millimetre) the geometry and surface finish satisfy the requirements for a good cutting edge. It is quite sufficient to hone just this narrow area in front at the cutting edge! This is made possible by a micro-bevel and a back bevel.

For a wedge angle (at the cutting edge!) of, say, β = 30° I start by grinding a bevel of 25° and then I regrind this coarsely ground cutting edge on a honing stone at 30°. Beginning at the cutting edge and increasing in width as I continue with the honing, this creates the narrow, micro finished micro-bevel. Even a micro-bevel just a few of a millimetre wide will reliably remove all traces of grinding with the coarse whetstone at the cutting edge.

Only a tiny amount of steel has to be removed for creating a micro-bevel – this takes just a few seconds even with a very fine honing stone. Moreover, no special effort is needed to keep the micro-bevel free of bigger scratches, because coarser grains or chips will not stick to its underside (as is the case with a larger area).




Another advantage is that you can increase the wedge angle on a chisel with a micro-bevel without having to regrind the whole blade. For instance, a cutting edge with a 30° wedge angle is overtaxed for mortising in hardwood: no problem, simply add a 35° micro-bevel to the existing 25° bevel. And next time you sharpen the chisel for another, less strenuous job you simply reinstate the 30° micro-bevel.

And finally: producing a micro-bevel substantially reduces the precision with which the blade has to be guided compared with the case where the entire area of bevel has to be honed. This is especially welcome for people who sharpen by hand. But remember: the micro-bevel must always be narrow, only then will you enjoy fast results in high quality!


Summing up the benefits of a narrow micro-bevel: - Honing, even with an extremely fine stone, takes a fraction of the time that would otherwise be needed - The quality of the micro-bevel and hence also of the cutting edge is especially good. - A chisel can temporarily be given a micro-bevel with a more robust cutting edge without extra effort. - THE MICRO-BEVEL GREATLY SIMPLIFIES SHARPENING BY HAND!!!





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