Evidently, I screwed up in a first attempt at sharpening a chisel. The 3/4" chisel had a good 1/16" missing from the corner. I switched to an much more agressive grit after 10+ minutes of not-much-progress at 220.
The nick is gone, but now I've got and put a radius over the width of the tip. It drops off by about a 1/32".
I don't have a grinder (maybe this is why the Lord invented Harbor Freight?) - and have two questions: a) How did I put the radius on there? Was I inadvertently applying to much pressure to one side? A sort of roll effect as I was sharpening? b) How do I get it out?
Light, firm pressure of the fingers on the middle of the chisel's iron. I sharpen mostly with a stone, not paper, but take, say, twenty oval strokes counter clockwise (oval circles of a few inches in diameter), then look to see the effect on the iron (what's the new, bright section that your 20 strokes just made), that will tell you where you're sharpening. Do it again to see if you can match the first result...and again, until you are sharpening where you want. Now sharpen so that the new, bright section comes in the center of the iron, at the same angle, again, and again. If you can't see the new section sharpened, then magic marker the flat you are sharpening, hit the 20 strokes, and see where the marker's removed.
Do some counter cw, some clockwise; do 40 strokes; do 60.... But always keep checking at intervals.
Hand sharpening is tedious, usually beyond my patience to get a really good result.
If you must use a bench grinder, go at it a bit at a time, use a white wheel (not grey) to reduce heating. IMO, the old, three-foot diam. hand or foot cranked grinding wheel produced a superior result because of the much greater radius vs. the bench grinder, and because there was no heat produced to destroy the temper of the carbon steel iron.
Ever since I read an article describing hand sharpening using sandpaper attached to flat plate glass, it's the only technique I use. I use self-adhesive paper; 150 grit up to around 400 (or higher if you desire). When it gets worn, I simply replace it. No more cupped stones, heat damage, etc. It may be heretical, but I move the blades parallel to the cutting edge, in a straight back and forth motion, front and back. It's easier to keep the edge flat, less "hook" is produced and you don't tear the paper. My planes have never cut so well.
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