Has anyone a cunning plan for sharpening the hollow chisel part of a machine mortice chisel? The inner shape is basically conical, merging with the square outer shape of the tool and I am aware that some manufacturers sell a conical grinding cone, but the only ones Google is providing are unbelievably pricey - in fact more than I can buy a complete chisel and drill bit for!
Veritas do a pair of diamond grit cones that do a good job, yes they are the price of a new chisel but will sharpen loads of chisels. I run them in the lathe with drips of light oil and gentle tailstock pressure. A light stoning to remove the external burrs and the jobs a good un.
"Andrew Mawson" on Sat, 7 Jul
2012 14:39:40 +0100 typed in uk.rec.models.engineering the following:Maybe so. But how many times do you have to not "buy a new chisel and drill bit" before you are ahead? Part of the reason they are so expensive is that you don't need one all that often, and you need a new one even less often. Specialty tools tend to be pricey just because they are specialty tools. By the sharpeners, then you don't have to buy new chisels. Buy the good sharpening tools, then you don't have to break down and buy the one you should have, and you get a better result on the tools you sharpen.
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Bob Minchin's post giving me details of the Lee Valley offering has put things into a more acceptable price bracket - thanks Bob. I've tentatively ordered a set of the diamond hones, just awaiting confirmation of shipping costs. In the last few months I have acquired two morticers (a Sedgwick normal chisel one, and a Dankerts chain and chisel one. Both came with a motley selection of chisels up to 1", most needed sharpening, so there is no shortage of sharpening fodder! Tilgear also offer a piloted countersink version which I have ordered, but it only does up to 1/2"/. I do wonder if it is feasible to mount a chisel in my cylindrical grinder headstock, rotate it 45 degrees off centre, and use a small internal stone at high speed to give an edge - probably only any good for the larger sizes.
AWEM
In message , Andrew Mawson writes
You could adapt a conventional internal grinding wheel to a *cone* using a diamond dresser mounted on the lathe toolpost with the cross slide set to some suitable angle. Grinding dust won't help the lathe bed:-(
regards
Well Tim that's not a bad idea, though I'd do it on my cylindrical grinder rather than the lathe, as it's set up to reject grinding dust!
AWEM
You could consider making your own diamond cone grinding point. I've turned the blanks for items and had the diamond coated by Asahi Diamond in the UK. Various companies offer the service and it varies with size and grit so may be worth enquiring.
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