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Deciding which Sharpening Strategy




The problem with sharpening threads on forums is that they all end up the same way - a million different methods and recommendations ... proving that everyone is wrong and I am the only one with the secret to the right way to do this!  

When deciding on a sharpening strategy, it is important to consider the type of steel you are sharpening. The softer steels, such as O1 (including laminated blades, even the Japanese with very hard cutting layers) can be honed on the full face of the bevel. However the harder and more abrasion-resistant steels, such as A2 and PM-V11, really need to be sharpened with a microbevel. The microbevel may either be a tiny secondary bevel or it may be a product of honing on the face of a hollow grind.

Generally, secondary bevels are easier to do with a honing guide if you are starting out, or if you have no intention of developing the handskills involved. With the latter, lifting the blade a couple of degrees as you move to the next higher grit, requires some practice to achieve relative accuracy, and for this reason fewer stones are preferred (less error involved).

For those freehand honing directly on the hollow, as I do, the process is made quicker if the hollow is done well. The best hollows are those that leave very little steel to hone, and the edge is straight. A straight edge may not require a coarse stone (eg 1000 grit) to straighten it before moving to a middle stone (eg 6000 grit).

The process is similar when using a honing guide: a straight primary bevel can be more easily converted to a secondary bevel with a middle stone if there is little work to do. This is why grinders such as the Tormek, belt grinders, and dry grinders with CBN wheels score so highly - they leave a cleaner and straighter primary bevel. Tormek blade guides, and similar blade holders, such as the Veritas, also facilitate a straighter grind and edge. Excellent work may be done freehanding and with white and pink wheels, but these do require more hand skill. 

More commonly, for those starting out, the magic bullet is not a great grinder or the best honing guide or the stones one uses. The magic bullet is knowing what to do, and what to do is to create a wire edge each time you hone a bevel (whether primary, secondary or tertiary). That is a guarantee that you are honing to the edge of the blade, and that is what you MUST do to create a sharp edge. All the above comments are geared towards achieving that wire. Anything less and all you are doing is polishing above the cutting edge. It looks pretty but is dull.

Honing on a full bevel is easiest when the steel is soft, and this is especially important if using the slower cutting media, such as oil stones. I included laminated Japanese blades in this category since the backing layer is often very soft cast iron and the hard cutting later is very thin - essentially the same deal as a honing on a secondary bevel.

Paul Sellers once posted a confronting 
video in which he sharpened plane blades with a 250 grit medium. The planes cut. Some (like myself) commented that this was not a true representation of sharpening needs, that is, the wood was soft and straight grained. But the point is that even a low grit can do the job. 16000 grit waterstones are not automatically the answer. 

The other recommendation is that what ever you use, use it for one year before you make any further changes. It takes time to get the best out of something.

For the record, I mainly use a worn 600 grit diamond Eze-lap diamond stone (which does not get used until the third honing - and can be delayed longer if I use my hardwood strop more frequently before the blade dulls appreciably), Medium and Ultra-Fine Spyderco ceramic stones, and end with Lee Valley green compound on a hardwood strop. I hollow grind on a 180 grit CBN wheel on a half speed dry grinder. This system has been in place a few years now and I have not wished to change it.

Regards from Perth

Derek


July 2017