Using the Work Sharp to flatten chisel backs

How flat is the sandpaper to the glass disc? If it is chattering, it makes me think that there might be a bump in the sandpaper somewhere. Sometimes, when you change the paper, residue from the previous disc can end up under the new one. I wipe the glass down with mineral spirits before adding a new sheet.

-- There is little that is simple when it comes to making a simple box.

What grit are you using to flatten the back?

-- Scott Smith, Southern Illinois

How much of the chisel’s back are you trying to flatten?

-- jay, www.allaboutastro.com

What grit sandpaper were you using? I’ve never needed to resort to power tools to flatten a chisel back, even cheapo Stanley Fat Max chisels.

-- Bondo Gaposis

I have a bunch of chisels (old, new and abused), including a Narex set. I had same problem as you so I tried different methods. The one below works for me.

First I try I flattening the backs on the WS3000 with power off. Just doing it manually. If an 1/8 inch from edge gets flat, I am happy and stop there.

Some chisels would take too long to do manually. These, I would lightly hold back of chisel in position on WS3000 before I turn the power on. I can do this down to 3/8 inch wide chisel. For some reason I can not do a 1/4 this way. I have to do it manually, which ain’t too bad; being small and all.

I start with coarse to semi-coarse sandpaper and work my way up to fine. I use that rubber stick a lot to clean up the sandpaper.

Also I use the right side of the disk with the sandpaper going away from the edge. And away from me BTW. :)

It took me a little practice. The bigger the chisel, the easier it was. So maybe start with your biggest chisel.

Hope this helps or you find something else that does.

The problem with using a WS 3000 for the backs of mortice chisels are that the chisels are fat and that makes them somewhat top heavy when trying to flatten the backs. I found this out when flattening the backs of my mortice chisels and saw right off that they do not get the same treatment as regular bench chisels. Because they are so fat, any little movement from side to side at the top of the chisel, which may seem minute or not even felt, equals a big movement of the chisel at the area being abraded. Thus, they round over very quickly. Once I figured that out, I made sure to keep that area absolutely flat on the wheel. I do it by using a light touch.

I suggest doing the thinner ones, 3/16 and 1/8, strictly by hand as it only takes a second or two to really mess those ones up. I also suggest using finer grits on the WS 3000 until you develop some muscle memory to keep the backs flat on the wheel. With the finer paper, you don’t take off so much metal during your “learning” phase.

Lastly, I wouldn’t get too hung up on getting the entire back surface of a mortice chisel flat and polished. As long as the business end is sharp, it will do its job. You won’t use a mortice chisel like a bench chisel (i.e. for paring and such), so you really don’t need to spend the time to polish the backs.

Good Luck!

-- Mike

I should have said that I have been able to flatten the backs of my larger bench chisels with the Work Sharp. Because those stay in place. The mortise chisels won’t. And you are correct: The slightest wobbling of the chisels results in a lot of metal being removed. I’m trying to get a Work Sharp induced gouge out with glass and sandpaper on one of them.

I’ve used 120, 220, and 400 grits so far. I’ve jumped between grits to see if any is more cooperative than the other. I checked for bubbles. There aren’t any. I’m using a combination of Klingspor discs and Work Sharp (Norton, actually) discs.

I’m trying to flatten as much of the chisel back as I can. I read you need to do that with mortise chisels instead of the 1 inch or so for bench chisels. Though I don’t entirely understand why as I doubt I’ll need to sink a chisel inches deep into a piece of wood

I don’t think a Work Sharp or similar is the way to go. Too easy to screw it up. Some things are just better done by hand.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

I suspect you’re right. I’ve basically abandoned the Work Sharp for this. How much of the chisel back needs to be flat? The chisels are several inches long.

Flattening is most crucial where the wedge of the blade and the back meet. If you are flat for about an inch from the edge down, you should be fine. The length of the blade is more for leverage than anything.

-- There is little that is simple when it comes to making a simple box.

I agree with David Craig (and others). I only flatten about an inch to inch and a half max on any of my chisels including the mortising. I use a WS3000.

-- Don't rollerskate in a buffalo herd

I don’t have any problems flattening the backs of my bench chisels with the Work Sharp 3000 (hereinafter “WS”). I have sharpened 1/2” to 1 1/4”. The package deal I got gave (sold me) enough glass disks so that I can have each grit on a separate side, so the only time to remove paper is when it is worn out.

Process I use:
1. Place the desired grit disk on the WS facing up.
2. With the WS running, lower the “back” of the chisel (closest to the handle) onto the spinning disk, with the sharp edge pointing in the direction of rotation. That is, a particular particle of grit moves from the handle side of the back to the sharp cutting edge. The other direction would have the sharp edge trying to cut the sandpaper.
3. Use a single finger to put moderate pressure on the center of the portion of the chisel on the disk.
4. Slowly slide the chisel back and forth (sideways).

-- Jesse, Saint Louis, Missouri

The bench chisels, at least the larger ones, seem to handle the Work Sharp okay. The mortise chisels not so much.

On the thinner mortise chisels I’m even having trouble keeping things steady with sandpaper on glass.

JesseTutt: Your technique is basically what I’ve been doing, except I haven’t moved the chisel back and forth.

I’m with MonteCristo. I feel that lapping 3/4” of the back and honing the bevel by hand (with a jig) is the way to go. I have had good luck with Norton waterstones: 1000, 4000, and 8000.

-- Paul, Clinton, NC