I have an old TH Witherby corner chisel. It definitely needs sharpeing and doesn't look like it's had it in a long time. I don't think it was maintained properly. the cutting edges are not square. In the corner it flares out below the cutting edge of the sides. I saw a new Barr corner chisel and it looks similar. So how the heck are you supposed to sharpen this chisel? What to use? What technique? Can it be done by hand without a machine? I'm assuming that you first start by flattening the back sides like on a regular framing chisel.
Thank you,
Brad

Yes, start by flattening the backs (outsides?). We use small Diamond Stones to hone the insides. I've been known to use the corner of my tormek wheel for serious cases. That "tip" in the middle is normal. If you want to really work that corner with the stones, you can knock it down, but it actaully doesn't get in the way as much as you might think. CB.

I figured that tip in the corner is important as it cleans out the corner of the mortice. It worked really nice when I borrowed a guys brand new Barr corner chisel and you could clean that corner out by hand pressure. I was not sure how to properly sharpen that corner tip... if there was a trick to it or something. I suppose I'll just figure out a way to play with that tip. Thanks!

Brad
Not sure if you have figured it out but you actually have two angle to hold when sharpening the corner chisel....the first is obvious, the angle on the face of the chisel. The other is esentially the same angle but on the other face.
Put the chisel on the left side of your stone holding the handle about 25 degrees up from the plane of the stone. Now also move the handle out to the left about 25 degreesfrom the edge of the stone. The other edge is of course is done on the other side of the stone.

A couple of strokes on one side then the other will lessen the chances of scoring one face deep which you would have to work out...then lap the back holding it FLAT to the stone. If you put any angle to the back it will cut out into the mortice rather than cutting straight down.

At least that is how I have done it with good results.

Bob