I think it's quite possible to get a 15 dps edge to 100 BESS or lower using the SG wheel and leather wheel with PA-70.
Best to keep it simple. We know there are two components to sharpening:
1) Apex the edge. Can you feel a burr all long the edge after your final pass on one side, and then on the other side? If so, the SG wheel has done its job.
2) Remove the burr. This is the hard part when it comes to getting very low BESS scores. You can get sub-optimal results if you:
a. Don't remove all of the burr, which can happen if you are honing at too low an angle, or if you don't hone enough.
b. Round the apex by honing at too high of an angle, or apply too much pressure when honing.
Freehand honing on the leather wheel is definitely something that takes some practice and muscle memory to perfect. You can work around that by using a front vertical base to hone with a jig, or keep practicing!
I would suggest marking the edge before you start honing so you have a better idea where the bevel is hitting. It's also helpful to use some kind of magnification to give you a better idea what's happening.
Lastly, I think it helps to minimize the burr as much as possible before you go to the leather wheel. One way to do that is to do a couple very quick, very light alternating passes on the sharpening stone.
Wootz's method generally involved honing at higher angles before finishing at the sharpening angle, depending on the steel involved.
Best to keep it simple. We know there are two components to sharpening:
1) Apex the edge. Can you feel a burr all long the edge after your final pass on one side, and then on the other side? If so, the SG wheel has done its job.
2) Remove the burr. This is the hard part when it comes to getting very low BESS scores. You can get sub-optimal results if you:
a. Don't remove all of the burr, which can happen if you are honing at too low an angle, or if you don't hone enough.
b. Round the apex by honing at too high of an angle, or apply too much pressure when honing.
Freehand honing on the leather wheel is definitely something that takes some practice and muscle memory to perfect. You can work around that by using a front vertical base to hone with a jig, or keep practicing!
I would suggest marking the edge before you start honing so you have a better idea where the bevel is hitting. It's also helpful to use some kind of magnification to give you a better idea what's happening.
Lastly, I think it helps to minimize the burr as much as possible before you go to the leather wheel. One way to do that is to do a couple very quick, very light alternating passes on the sharpening stone.
Wootz's method generally involved honing at higher angles before finishing at the sharpening angle, depending on the steel involved.