Derek Cohen (in Perth, Australia)
How so? I don't touch the flat (back) so there is no back bevel; if I [can] keep the bevel flat on the stone (I freehand) then the bevel angle doesn't change. Ideally, the blade just gets shorter, no angles change.

Hi Craig

No matter what type of blade you use - paring or mortice chisel, BU or BD plane blade - the bevel will wear on both sides. It wears on the bevel face and on its back (sometimes these terms are used interchangeably, or the other way around - can be very confusing - but you know what I mean).

The photos that Steve posted (above), that Larry praised (quite rightly in my view), were some of the best I have seen of a wear bevel on the back of a blade. In this case it was of a BU plane blade. It was also interesting, with the longstanding BU vs BD debates in mind, that the simple use of the Ruler Trick to avert the affects of this backbevel is sufficient.

The thing is that a similar backbevel occurs on a chisel as well. Most chisels are used BU, hence one should expect wear on the back of the blade as well as wear on the bevel face. Honing only the bevel face is likely to leave the wear bevel intact. Honing the back of the blade must be done thoroughly to remove all vestiges of the wear bevel. On chisels it is not advisable to use the Ruler Trick (as this affects registration when needed). The danger of honing only the last 1/2" - 1" of a blade back is that you end up with a long and shallow backbevel (losing its coplanar flatness).

Regards from Perth

Derek