Chisel Sharpening.

[Don Kingston]

I bought some, I mean Santa brought me a set of narex mortise chisels for being a good boy this year, Do any of you mess with the sides like you do the backs when you get new chisels?
Thanks
Don

[Kees Heiden]

No. Not at all.

[john zulu]

@Don we don't mess with the side for a good reason. Let's say the chisel is 1/8 inch wide. After messing with it. It will be less then 1/8 inch. If you depend the chisel to 1/8 with your other chisels you be out of luck.
Second is the corners. We don't round them because the registration is no longer there. Just try to chisel out a corner with rounded edges. You never get it square.

[Warren Mickley]

A mortise chisel is sophisticated tool; much of the precision and the ease in making the mortise derives from the precision and set up of the tool. I have not used Narex mortise chisels, but I have examined a friend's set right as they came out of the box and my impression was that they are carefully made. Unless there is something noticeably wrong I would use them as is. I have routinely worked on the sides of antique mortise chisels and I once worked on the sides of a set of Two Cherries chisels that came from the factory in unusable condition.

There is trouble if the chisel is wider say two inches behind the cutting edge than at the edge. In this case the cutting edge cuts a certain width channel but the sides of the chisel must then compress the sidewalls of the mortise and the chisel is difficult to extract and difficult to maneuver in the cut. For this reason some users and some manufacturers make the chisels with a very slight taper form tip to bolster. Theoretically this taper is not necessary, but it does insure clearance for the tool.

In a like manner there is trouble if the bevel side of the chisel is slightly wider than the back. The chisel can also become sort of trapped and stiff in the mortise. Some workers like a definite taper back to front (narrower) so the chisel is very slightly trapezoidal and there is definite clearance. Some like just a very square chisel where the front is the same width as the back. Both these tapers, along the length and front to back should be extremely subtle. I find it less than ideal if I can actually notice a taper in use, which sometimes happens.

The sides of the chisel also cannot be convex, also for clearance issues. The great danger of abrading the sides yourself is that this will occur unintentionally, so any adjustment should be done with extreme care. Toshio Odate illustrates mortise chisels with concave sides, which is helpful for clearance issues and makes the side edges slightly sharper. I would try this myself if I thought I could do it in any kind of controlled manner. I believe Odate's chisels do not have taper, just very carefully made.

The exact width if a mortise chisel is of little consequence. The width has to match the mortise gauge and that is all. I have two 1/4 inch mortise chisels and one is slightly wider than the other, but after 37 years I don't know which is closer to exact measurement or how any other mortise chisel compares with its nominal measure.

[Don Kingston]

Thank You All. I know I would not attept to do this myself because of lack of expierience. I haven't checked the width but they appear to have the machining marks thats all. Thats why I asked. I thought maybe doing the back properly and doing the bevel face properly would make any side issue mute. Was asking out of curiosity.
Thank You and Happy New Year
Don

[Jim Matthews]

I might ease the front corners a little with a honing stone,
if I cut myself handling them. Otherwise, I wouldn't.