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I just bought a T-7 and proceeded to sharpen all my chisels. I ran into a problem with a 1/2" mortising chisel. It would barely fit into the square edge jig, not enough protrusion to get the desired 30 degree angle. Is there a jig recommended for larger mortising chisels. I was able to sharpen my 1/4" and 3/8"; the 3/8" stuck through just enough to get the angle.
Larry
Hi Larry,
I ran in the same problem with a nice Japanese mortising chisel and sometimes I sharpen it free hand with the wheel rotating away from me, but I got from Lee Valley a blade holder they use for their motorized sharpening system that is able to hold the chisel properly. Their support is about 20$ or so and I use it also with the wheel rotating away from me. My chisel is thicker than the square edge jig.
Ionut
PS I found the link, it is this one I use: http://www.leevalley.com/wood/page.aspx?c=1&p=32974&cat=1,43072,45938
Another option, which I should have thought of earlier, is to treat the mortising chisel like a turning parting tool.
When I sharpen a turning parting tool, I use the SVD-110 Tool Rest. I align it so that it is square to the stone and hold the tool flat on the plate, with the bevel established by eye. To align the Tool Rest square to the stone, hold a straight edge on the table so that it extends past the side of the stone. Adjust it so that the straight edge goes through the center of the stone shaft, then go below center by half the thickness of your chisel. There are drawings of this in the TNT-300 Woodturning Instructions booklet.
If I understand you correctly the plate on the jig would be square and offset down 1/2 the thickness of the chisel. then the chisel would be held on the plate at a 30 degree angle from the axis of the wheel and ground.
I suppose one could just set the plate to get a 30 degree bevel and use it as a grinding rest, plunging it (not literally) into the wheel, not sliding it side to side.
Larry