Sunday, 26 August 2012

A Bright Sunny Day

Now that the back  is flat and the bevel is ground it is time to hone.  A quick note: some people say that honing and polishing are two steps; I flatten, grind and hone (three steps, it may be weird but I like it).  Whatever you call it the final stage is the time to finish the edge of the tool.

The honing setup

Honing is the process of using progressively finer grits to achieve a polished bevel.  I use Norton waterstones and hone on the 1000, 4000 and 8000 grit stones.  Some people go to a higher grit (possibly 150000) some people use fewer grits (maybe just 1000 and 8000) the idea is to achieve a highly polished surface.

Surface after honing on 1000

I move straight to my 1000 grit stone after grinding no need to adjust the jig at all.  I flatten the stone like I flatten my 220 grit stone.  I move the jig the same way I moved it for the grinding procedure, I try to use all of the stone to ensure even wearing.

Surface after honing on 4000

Once the scratch pattern is consistent on the 1000 grit stone I move to the 4000 grit stone and then on to the 8000 grit stone.

The highly reflective surface of honing on the 8000 grit stone

And with that the blade should be sharp and ready for use.  However there is one final step that can be done to make things easier for future sharpening.  A micro bevel is a small area of the primary bevel that is sharpened at a slightly higher angle then the rest of the bevel.  The reason for a micro bevel is to reduce the area needed to be resharpened to achieve a sharp edge.  With my system after I finish the primary bevel I turn a small nob (a really nice feature of the Mk.II Jig) and pull (and only pull) back on my 8000 grit between  5 and 10 times.  This creates a new small bevel that is much easier to sharpen down the road.  When I need to refresh the blades edge a few strokes on the 8000 grit stone and the edge is ready to go again.  Like the jig or no jig and waterstone or oilstone debates Micro Bevels get a lot of discussion.  How big should it be, what angle should it be, is it really necessary?  I do not care for these questions, for me the micro bevel is just to improve efficiency.

So here you can see what a sharp edge can do.

 Cherry in the rough.

Cherry after the touch of a sharp chisel.

Super wispy shavings on pine.

Finished surface of pine.

So now the edge is done.  Final question, when do I resharpen?  Unless I push my edge through a nail or some dirt or drop it I shouldn't need to regrind the edge or flatten the back.  I do rehone the edge once the micro bevel is to a size that it is no longer an efficient way to resharpen the edge.

There you have it, my three step process to achieving a sharp edge on straight bevel tools (IE. straight plane irons and chisels).  If you have any questions on this process please post a comment and I will answer it.

Hans Christopher