HRRLutherie
Established Member
I found an interesting link that showed that cutting mortices with ordinary bevel edged chisels is quicker and neater: http://www.youtube.com/watch?v=q_NXq7_TILA
Er, what is a 'wrong primary bevel angle'?Peter T":zlpq3zph said:I'm guessing anything would be quicker and neater than that dreadful excuse for a mortice chisel, with the wrong primary bevel angle!
Pete Maddex":1gj0ivd4 said:I've gone even further, I sharpen screwdrivers on the step out side and bash them with a brick :shock:
Pete
The main point behind the OBM is sheer strength. It's a hand tool for fast production work done by people working against the clock. A bevel edged chisel wouldn't survive this, but is fine for an amateur woodworker pottering about with small furniture stuff.Fromey":29nud89q said:I'm sure it can be done both ways. In fact, he showed that it can and I've done it myself. However, I thought one of the design reasons behind mortising chisels was their thickness. Yes, it makes them more robust and avoids bending, as Paul Sellers warns about, but it helps register the chisel against the walls of the growing mortice, preventing your chisel accidentally twisting. Normally I don't cut a mortice with an unyielding and proud sheet of glass helping to guide my chisel....
Jacob":u01bjl7i said:Er, what is a 'wrong primary bevel angle'?Peter T":u01bjl7i said:I'm guessing anything would be quicker and neater than that dreadful excuse for a mortice chisel, with the wrong primary bevel angle!
Who says? He's wrong whoever it is.Peter T":16n5355i said:Jacob":16n5355i said:Er, what is a 'wrong primary bevel angle'?Peter T":16n5355i said:I'm guessing anything would be quicker and neater than that dreadful excuse for a mortice chisel, with the wrong primary bevel angle!
The primary bevel on the mortice chisel should be 20 degrees or less.
30º is fine for a thin bevel edge chisel. I haven't looked closely but I guess it'll be a convex* bevel with an edge about 30º and the bevel falling away indeterminately.That one look more like 30 degrees.
Jacob":t76ojoe1 said:The main point behind the OBM is sheer strength. It's a hand tool for fast production work done by people working against the clock. A bevel edged chisel wouldn't survive this, but is fine for an amateur woodworker pottering about with small furniture stuff.
Fair enough but there isn't a fixed rule. If it works it's OK. A rounded bevel is common - this makes levering out easier, from the bottom/edge of the holePeter T":gc8cqa65 said:Ray Iles mortise chisels come with a 20 degree primary bevel and a 35 degree secondary to prevent the edge from crumbling.
These work very well in hardwood!
See! ......I told you!phil.p":2377hwus said:#-o Here we go again! #-o
phil.p":3em6xfo0 said:See! ......I told you!phil.p":3em6xfo0 said:#-o Here we go again! #-o
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