The Sharpening FAQ

	The FAQ
	Finest abrasives.
	Microbevels front and back.
	Use a jig.

	Copyright (c) 2002-15, Brent Beach

This page started life as a small Question and Answer page for the jig. I have since added a number of other topics related to sharpening plane irons. Over time I will add more related material, perhaps with hooks into the sharpening pages.

The fact that these questions get asked suggests that the answers are either not obvious, or that my answers are somewhat different from commonly held views.

Scary Sharp

Back in the early days on the internet (Nov 1995), on a Usenet forum called rec.woodworking, there were a few discussions on sharpening hand tools. One contributor, Steve LaMantia, sent a longish message about his discovery of sharpening using abrasive paper stuck on glass that he called "Sandpaper Sharpening". He claimed the tools got so sharp they were "Scary-Sharp (tm)". The term has entered the folk lore of hand tool woodworkers.

A lot has changed since then, both with tools and with abrasives. Lee Valley and others have re-created the market for quality hand tools. Abrasives have come a long way as well - with advances in artificial stones (mainly water-stones) and diamond abrasives.

Scary Sharp - the really early days.

It turns out Steve was not the first person to try abrasives on plate glass. In 1863, Henry Clifton Sorby was working with microscopes and steel. His interest was the structure of steel. He had previously studied minerals using the same basic technique outlined next.

If that name seems familiar, it almost is. Henry was the son of Sorby family that owned Sorby and Sons of Sheffield. He was never active in the firm. We was only 18 when the firm which was sold in 1844. He did these experiments in 1863.

Sorby was trying to discover the structure of steel. Others had tried to smooth the steel surface and look at under a microscope. Sorby perfected the techniques of smoothing the metal sample. Having glued a slice of metal to a piece of glass, Sorby had the "surface made us flat as possible by rubbing on emery paper placed on a sheet of plate glass, using in the first case somewhat coarse, and finally the smoothest paper employed in preparing sled plates for engraving." Preparation involved other abrasives after the scary sharp step.

Emery in the 1860s was the naturally occurring mineral containing aluminum oxide and other compounds. Naturally occurring abrasives are not as uniform in grit size and shape as modern industrial abrasives.

Henry spent just a year discovering Metallography, then moved on to other challenges.

Scary Sharp - the early days

The process Steve described used 11 different abrasive grits. The abrasives were bought from a variety of sources. Steve used a spray adhesive to stick small pieces of each abrasive to a sheet of glass. He used an type 1 Veritas honing jig.

Is my system just Scary Sharp?

My system started there, but a few things changed along the way.

I use only a three grits during honing (Steve used 11!).
All of my abrasives are finer than all but the last grit Steve used. Not only do I use finer grits, I use better abrasives where it counts - when honing the edge. I still use the 3M abrasives mentioned by Leonard Lee in his book on sharpening (1996), although I now grind using Silicon Carbide bench stones.
I use a shop made jig that slides on the glass rather than a commercial roller jig that rolls on the abrasive. Commercial jigs were unable to give me the microbevels I found to be necessary.
I use more microbevels (a new microbevel for each abrasive, Steve only used two honing angles). By using a new slightly larger honing angle for each abrasive, I am able to begin honing with each finer abrasive right at the edge. If you hone the entire honing bevel with each grit, then you need many abrasives and it takes much longer.
I use microbevels on both the front and back of a plane iron. Steve lapped the back, I hone the back. This page explains why back bevels are important.

A big advantage of using only 3 abrasives, with a new microbevel for each abrasive, is that you can see when you are done with each abrasive. No need for a magnifier. You can see if the microbevel at each stage is the full width of the blade, right at the edge. The visual check for done for each abrasive is discussed in detail in the typical sharpening session page. The elapsed time on the three abrasives should be no more than 3 minutes, assuming the blade has been properly ground (down from Steve's 15 minutes). Watch the video of me honing a plane iron to see how long it takes.

Is sharpening with sheet abrasives on glass hard or easy?

Sharpening with abrasives on glass can be hard or it can be easy. It can work really well, or not work at all.

If you buy cheap abrasives you will not get a good result. If you do not stick the abrasives down on the glass really well you will not get a good result. If you do not use a jig at all you will not get a good result. If you do not use microbevels as discussed here you will not get a great result. If you don't bring a well ground iron to the honing stage, you will not get a good result.

If you take the time

to assemble the right equipment and
make the honing jig
make the stone vice or are quite good at grinding on a belt sander

then you will get superior edges with a minimum of effort. Every time.

If not, not.

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