Hi Vadim,

Could the angle issue simply be due to the reduction in the jig projection length during grinding, as illustrated in the schema diagram in your initial post? If it is would it not be better to recheck the projection after each grinding step in your sharpening procedure, and if necessary return to the initial projection length using the adjustable stop? Perhaps such a tweak is all that is needed to ensure the target edge angle is always maintained.

Or may be I've missed something and it is not as straightforward as I think

Andrew

I wish it were that simple.

What we've been doing for the last 2 weeks - grouped knives by blade thickness behind the edge: under 1mm, near 2mm and near 3mm, and sharpened each group from 10 to 20 degrees at 1-2 degree step, on two T8 and two T7 machines, in the standard position and edge-trailing using our Frontal Vertical Base.

The laser protractor numbers tell us that the ground angle we get depends on 4 factors: the angle, the thickness behind the edge, whether the blade is double-bevel or single-bevel, and whether the grinding is done edge-leading or edge-trailing.

Our formulas now factor in the difference between the double-bevel and single-bevel blade, and the blade thickness behind the edge. It is not the same as the thickness at the spine, so has nothing to do with modifying the knife jig to center the blades better. You can have a blade 5 mm thick at the spine but thin behind the edge. But of course, you still have to center the blade in the jig as practical.

The new computer algorithm in our software not only has formulas that factor in the blade thickness, but also follows the experimental numbers we've obtained for each edge angle from 10 to 20, ground edge-leading vs edge-trailing, to grind the correct target angle no matter what.

We've made a big change from a pure theoretical algorithm to the one fine-tuned by 100 of experimental sharpenings. This makes the match to the honing angle perfect. At the end of the day, all the man-hours we've put into this improvement are to better the deburring and sharpness.