See our previous post, How to Sharpen a Chisel, Part 1, for basic sharpening techniques.
Medium Diamond Stone
So now the burr is gone–in fact, the burr is on the bevel side. Now go to the medium stone and–surprise! Work it the same way as on the coarse stone: find the angle on the bevel side and work it back and forth. I like to work in a circular motion, because it helps maintain that bevel.
So just continue to work on this stone, back and forth. Again, feel for the burr. You’ll want to feel it right across the back of the chisel. Keep going until you get a nice, consistent burr. When you’re done, take the burr off on the back of the chisel, on the fine diamond stone. Remember to make sure that the back must be held perfectly flat as to not raise up the back of the chisel in any way. It MUST BE PERFECTLY FLAT!
(See our previous chisel sharpening blog on how to find the angle and take the burr off.)
Fine Diamond Stone
Now that the burr is gone from the back, bring the bevel to the fine stone. Maintain the same bevel and just work it.
You can hear the difference from the coarse to the fine stone. The finer grit takes off less material, but also starts polishing the edge. Again, work it until you can feel the burr on the back of the chisel. Then take the burr off using the fine diamond stone.
Hard Translucent Oil Stone
We are almost done…. Now we go to the hard translucent oil stone. On the oil stone, put a little 3-1 oil; that helps keep the stone from getting clogged up with metal particles. Put the bevel down just like all the others. (My oil stone is in a wood holder that I made to protect it from dust and from breaking)
Again, feel that bevel. Use the whole stone. The advantage of doing this freehand, without a guide, is that you can use the whole stone. So you don’t have to worry about the stone wearing unevenly. (As mentioned in my post on oil stones, oil stones will wear out a hollow if you don’t use the entire stone, so its best to use every corner of the whole stone. Work the bevel of the chisel using moderate pressure and feel for the burr.
As with every time, feel that burr. Make sure it’s all the way across the back of the chisel. Flip the blade over and work the back on the oil stone to remove the burr. Again, you can’t even hear it cutting, but it is; it’s polishing it.
Sometimes I’ll work the blade again on the bevel, maybe applying a little lighter pressure so the burr is much finer. It’s there; very subtle. Then one last swipe or two on the back.
Last, but not least, strop the chisel. A strop is a piece of leather adhered to a block of wood and charged with some buffing rouge–chromium oxide. It often comes in a crayon-like plug. Just rub the “crayon” on the rough “suede” side of the leather, which is face up. You don’t have to rub it on every time you sharpen. One charge will last you a couple weeks. Clamp the strop in the vise if it doesn’t have rubber feet or a holder.
Put the chisel bevel down. Always pull the chisel on the strop. If you push, the chisel will cut into the leather. So maintain the bevel and just go a couple times. Again, one of the things you don’t want to do is to round the bevel over. Of course, as the leather is somewhat soft, it’s going to round it just slightly, so if you polish it too much, you could round the edge too much. There’s nothing really wrong with that, other than it makes it harder when you go back to resharpen because you’ve got to take that round off.
Look at that polish! The chromium oxide is actually about 0.5 microns–the smallest particle size, very fine. It’s actually just barely abrading and polishing the edge, making a super-sharp tool.
There you have it–the polished tool. There are a couple ways to test your sharpening job. One way I do it is to test it on my fingernail. If I hold the chisel up as close as I can to the blade, and then test it by just touching it to my thumbnail and if the blade catches, I know it’s sharp. Make sure to hold the blade as flat as you can to the nail, the flatter you can hold it the better, if it catches the nail then you know it is sharp. Again, I am just touching it to the nail, not carving my nail away!
Of course, you can do the paper test. Take a sheet of paper, hold it flat, take your chisel in the other hand and try to slice through the sheet. It should cut through like a knife through hot butter!
That concludes this sharpening blog. Please check back for more in-depth sharpening techniques in our next blog series.
I highly recommend that you watch the free video I did on sharpening a chisel. Then go to your shop and start sharpening up your tools!
(Photos taken from video)