Hi faithful reader whose patience I must push to the limit,
Just recently, I was asked about putting microbevels on Japanese chisels, which I duly answered, and then it dawned on me that I should stop just answering questions privately, and put up answers for everyone to see. Sure would save repeating the answer again and again and again…
From this point on, when a good question comes up, and I answer it, I’ll also post the answer here so that everyone can have a read, and maybe even poke holes in what I write.
So here was my response to the question, “Should I use a microbevel with a Japanese chisel?”
There is more than one reason why a microbevel on a Japanese chisel is a ‘Bad Idea’, and conversely, very few good reasons to do it.
The main reason is that, as you should already know, the edge steel is very hard, and because it’s a relatively simple steel, also brittle. Using a full bevel, the edge is closely backed up by the softer, far tougher but ‘soft’ backing iron helping the hard steel resist chipping. Using a microbevel, the hard steel is ‘swinging in the breeze’ and more likely to chip or snap.
The next is that because the edge is made up of a thin layer of hard, grind resistant steel and backed up with a larger mass of soft, easily ground iron, that abrading a full bevel takes very little effort, when compared to a full bevel composed of hard, tough steel. The better the chisel, the easier it is to work that full bevel. Lower grade Japanese chisels are still quite easy, but as you go up the quality/price scale, the edge becomes easier to grind and sharpen. Alarmingly so with something like a Tensho chisel. In short, a microbevel defeats the purpose, since the chisels really are easy to sharpen when compared to anything else.
Believe me, if a microbevel had any advantages for a Japanese chisel, it would be used. Micro/secondary bevels are suggested for the local HSS chisels, since the steel is more difficult to sharpen so it is not like the chisel makers are not aware of it, or scared to recommend it.
Maybe the only advantage of using a secondary bevel on a Japanese chisel is to alleviate chipping in very demanding woods. But even then, it’s a stop gap and if you plan to increase the bevel angle to something steeper than 30 degrees (pretty much standard) then you should continue it until the full bevel has been re-established at the steeper angle.
I hope that’s understandable. It’s not an arbitrary thing, there is solid reasoning and experience behind it. Like all things though, you are welcome to do whatever you wish to your own tools.
And that’s it.
I hope that’s a nice stop gap for the dearth of info that’s been posted of late. I really wish I was able to put stuff up here more often, but danged if I can find enough time to do it they way I like to do it, as well as possible and thoroughly researched. I suppose my ‘off the hip’ stuff will just have to do.
Thanks for reading, and your unending patience,
Stu.
