I have just been using a corner chiselw for the first time. I bought it off of ebay, it needed a fair bit of fettling to get it right. It had been badly sharpened on a rounded over stone also the back nar the cutting edge had been badly rounded over by careless backing off and/or clumsy use of the dreaded belt sander. It resembled a fishing spear type of thing with a prominent "point". Any way i went through the emery and glass routine-for hours-to get the back smooth and shiny to the edge, polished with a fine stone and GENTLE buff. Ground the edges square across, then I reshaped the cutting edge with files, I use then more and more for shaping nowadays even axes etc. (I would happily do without the power grinder, in fact I just bought one of those fast coarse 250 japaneses waterstones to do this sort of task) Then finished with fine stone etc.
I dont know why I never used a corner chisel before I love it when you drive it in it stays exactly in line, and pop it forwards just like a mortice chisel to clear the waste when your deep enough. I cut some 1 inch x 5 inch mortices today 3 inch deep, took less than 10 minutes each including drilling with brace and bit.
