The Delta Mortiser instruction manual says the clearance between the chisel and bit should be between 1/16" and 3/16" --- depending on the type of wood. In the past, with a drillpress mortising attachment, I've always set the clearance at about 1/16". From your experience, which species of wood require the larger clearance?
Joel
3/16"? I guess I'd ask Delta. I won't pretend to know more than they do about mortising chgisels and bits, but it sounds like a misprint to me. I usually set mine around 1/32" - jst enough to keep the bit from rubbing.
John Martin
I haven't used it much yet, but with the 1/4" chisel in hard maple I had to set it to at least 1/8" or else the chips would just jam up the bit.
-Leuf
The bit in hardwood will make fine shavings. In soft wood you frequently get the grain to tear rather than be shaved. If you leave a bigger gap between the chisel and the bit you're apt to have the bit deflect in the cut - and leave room for chips to jamb between it and the chisel.
Here's The Forty Cent Method for bit to chisel gap.
charlie b
I use the 40 cent method on my mortiser.
You MUST tune up the chisel and bit. They are NOT sharp from the factory. Lee Valley sell a tool for doing the inside of the chisel. Hone the sides on stones as you would any cutting tool. A small file will do the side of the bit.
and bit should be between 1/16" and 3/16" ...
have the bit deflect in the cut - and leave room for chips to jamb between it and the chisel. ...
wood tearing and clogging things up.
I had a conical stone on a shaft, but it seems to be on a long vacation. I'll get the Lee Valley set-up -- and file the inside corners a bit.
Thanks again, Charlie.
Joel
I saw the original post suggesting the stuff from Lee Valley, but when I tried poking around their web site, I didn't see it myself. Would you post a URL for this tool?
Thanks!
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