sharpening corner chisels?

Another thread wanted to know about beveling a corner chisel....rather than ruin that thread..I'll ask the "Sharpening" question here..

HOW do you sharpen one of these?
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As I haven't really needed to use this one..yet. 1" on each face.
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Who ever had this before me....didn't do a very good job..
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And the bevels are convex, to boot. edges will trim a fingernail with ease...chisel just bounces off the wood....
And, there was a special way to sharpen one of these....anyone remember? something about the corner where the two bevels meet.
The edges on this one are full of knicks....would like a flat bevel, as well...

I used an 8" smooth file on mine. I can't remember what brand it is. It was purchased new in the mid '80's. The metal is nothing like as hard as bench chisels. I remember wondering if it was really worth having when I ordered it, but if you get the corners straight in large timber framed mortises, it makes getting the mortise sides good easy, when they are in line with the corners. I built a 2-story timber framed porch on a spec house in 1983, so that's when I accumulated some timber framing tools.

Lie Nielsen website recommends using a fine grit slip stone with square edges for sharpening theirs.

Also just checking but are you just paring the corners or trying to hog out material? The mortise should already be chopped out and the corner chisel would help finish the corners at a 90 degree angle.

I expect the LN ones are hardened more than mine is. I wonder how hard the old ones are compared to bench chisels.

The way I used it was to drill most of the mortise out, rough flatten the outsides but not carry them all the way to square with the timber face , then using the corner chisel to go straight down by checking with a square on the chisel, rather than so much checking of the mortise itself, finally connecting the corners. They are always multiple ways to do almost anything in working wood.

That makes sense Tom, I was asking that of Steven because he said it “bounces off the wood”.

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At one time, I had this 7/8" PS&W Co. corner chisel....the other was an 1-3/8" Framer chisel.
I seem to recall, that the corner where the two bevel met, had to stick out a hair farther than the rest of the bevels. Not sure IF it was a small skew for both bevels.

Was wondering how these were sharpened. Since 99% of my mortises nowadays are about 1/4"...not much need for the 1" I have now..