How to sharpen a chisel by Tom Perkins of Vintage Tools NE

[Jim_Rogers]

Some time ago, we started an eNewsletter that we send out to people who have bought tools from us.

I asked in the eNewsletter what topics would they like to see in future editions to the eNewsletter.

One request was to show how to sharpen a chisel.

In February of 2012, I went over to Tom's workshop and took some pictures to go with the story he wrote about how to sharpen a chisel.

We sent this story out with February's eNewsletter.

I have uploaded the photos to my "sharpening" gallery and wanted to share this story with you.

So here it is:

Here is the procedure I use to recondition a chisel. The procedure is the same for a new chisel as well as an older laminated chisel that has probably not been taken care of properly. It maybe pitted, nicked, improper angle on the cutting edge, or the edge may no longer be perpendicular to the side. All that being said, let me assume that the edge IS 90° to the sides and there are no other major problems to address before the sharpening process. If you need help with those areas, just ask and I will fill you in on how to deal with those concerns.

Ok, so you have a chisel that has MINOR pitting/rust, here is the first area to work on. Both the back and bevel MUST be free of pitting at the cutting surface.
To remove the pitting the easiest way, if you do not have a stationary belt sander, is to use a sheet of either silicon carbide paper or the screening used to sand sheet rock mudding compound. Both can be bought at a good hardware store. The screening is the best way to go, but either will work. To make sure the screening sits perfectly flat, pick up a piece of 1/4" tempered plate glass at least the size of the screening, usually 10"X 12".

Ok, here we go!

1) Put water onto the screening that is on the plate glass and, keeping the back of the chisel DEAD FLAT; rub the chisel back and forth. You only need to remove the pitting from the first couple of inches or so, so that helps make this step go a bit faster, though a belt sander I mentioned before would be a lot quicker. This step will take time so be patient! Once you see that the pitting has all be "ground" away on the back surface, do the same to the bevel. If the pitting on the bevel is minor, you can skip this step and the stones will accomplish that in the next step. At any rate the angle you want the bevel to be is 25°. It is not essential that it is EXACTLY 25°, but pretty close. You can buy jigs to set the angle you want and can help you "learn" the proper angle. After awhile you will able to do it by eye.



2) One thing you must understand is that an edge is the juncture of two surfaces, and therefore BOTH have to be polished to give you the finest cutting edge possible.

The first stone I use is an 800 grit Japanese water stone. Keep the back of the chisel FLAT against the stone as you work it.



3) It will soon become apparent if you have removed all the pitting as the color of the steel from this abrasion will turn a fairly dark grey. Once you have the back a nice grey color from the edge to about an inch back, now do the bevel.



4) Make sure you match the same angle, take a couple of strokes, then look to see where you are hitting, and adjust your angle accordingly. Again, once you have the bevel completely ground to that even grey color, you can now go to the second stone, a finer grit- 1000 or 1200. Repeat the above process for this grit.



Above is a double sided stone.





You will now see that the surface will now be much more refined, and shiny. Make sure this shine is across the entire edge on both the back and the bevel.

5) The next stone is 6000 grit water-stone.





The procedure for the back is the same as it was for the other two stones; however the bevel is a bit different. After "polishing" the back of the chisel, yes you should now be able to see your reflection, the bevel is done this way. Instead of trying to match that 25° angle, you raise that angle to about 30°. Now 5° is not much so err on the side of less. After you have a highly polished edge on the bevel of no more than 1/16" and preferably 1/32", you then move onto the final step, stropping.

6) Stropping is done with piece of leather than is mounted on a wood base



Above is a shot of the bottom of the piece of wood. The attached rib is so that I can hold it in my bench vise at the right height for me to sharpen chisels.

The leather is "buttered" with a stropping compound; I use Yellowstone from Woodcraft supply.





The process is similar to the honing. Lay the back of the chisel FLAT onto the strop and then with moderate downward pressure, pull the chisel back toward you. Repeat this a half a dozen times or so.



And then do the bevel, matching the 30° polished angle. Again it is better to be a little less than 30° then more but you should be able to do this with just a bit of practice.



At this point you should be able to "shave" the hair from your arm!

Now for the bad news! Doing a corner chisel, though done the same way is at least 10 times harder all because you now have 4 surfaces. AND they intersect at 90°! It is VERY hard to get that "corner" and usually you have to use small slip stones to access that trouble area. If I were you I would hold off trying to sharpen that until you get a LOT of practice on regular chisels. I, myself would rather sharpen 10 chisels than to do one corner chisel! I do do them but I don't really like it, especially if the chisel has problems pitting, bad grinding, etc.
Total time to do all the steps above to restore a chisel back to good working order should be around an hour.

Tom Perkins, Vintage Tools NE.

[dukndog]

Great info Jim!!!