Increase (raise) the angle by 0.1 degree after each stone. Fixed angle sharpening

[mikee1]

I have seen some videos on Youtube where they change the degree by 0.1 degree after each stone even if they are using the same kinds of stone (same thickness).
I also saw it in a video from TSProf but didn`t get an explanation why.
They have 5 stones. They start sharpening on 15 dps.. and raise by 0.1 so they finish at 15.5 dps after 5 stones.

Is there a reason why they do this ?
Is this the preferred way of sharpening with fixed angle systems ? And what are the benefits of doing it this way.

 

[Rob Babcock]

I don't do it but I've heard of folks doing it. I suppose the idea is to create a small amount of convexity to the edge. Raising it such a small amount seems like might be too small to reliably measure with accuracy. My practice is to keep the same angle. Occasionally with a kangaroo strop I'll lightly strop at a minutely higher angle to ensure hitting the very apex.

 

[Diemaker]

I used to do this on the last stone, until I found out it increased my BESS scores 40-60 grams. The idea is to make sure you reach the apex with the stone. Strops generally convex anyway so no need to with them.

 

[Obsessed with Edges]

With some ductile steels, burrs created with a fixed angle system can sometimes get ridiculously wide and very thin without breaking off. This is because the fixed angle prevents contact with the burr as it slightly deflects away from the stone. Raising the angle slightly helps to bend the burr further to the side, so it can be scrubbed away from the other side more effectively. I noticed this effect when I used to use a guided system for sharpening, when the burrs I created became much too wide and were nearly impossible to scrub away unless or until the angle was raised a bit in the refining stages.

Others may have their own reasons for raising the angle. If anything, just a tiny microbevel can help strengthen the edge and improve edge retention. And as others have already mentioned, slightly convexing the grind behind the apex can benefit the edge the same way.

 

[FortyTwoBlades]

I used to do this on the last stone, until I found out it increased my BESS scores 40-60 grams. The idea is to make sure you reach the apex with the stone. Strops generally convex anyway so no need to with them.

Could probably compensate for this by sharpening at half a degree lower then apexing at the true desired angle.