I did not mean to take issue with anything really, I was just trying to refine the statement a bit. Explicitly:
the use of the stop collar does effectively eliminate the issue of multiple stone thicknesses,
except when the stone arm and pivot mast form an angle significantly far from 90° and the stone used is slow-cutting and unyielding. We agree on the bold part but I don't know if I have yet convinced you of the italic portion?
Here is a labeled diagram for ease of reference. The blade table is on the bottom, the pivot mast is on the left; both in blue. The stone arm is green. The knife would sit with its edge at vertex A. The pivot is at D. The pivot is raised to an extreme height to best illustrate the item of debate.
The red line AC is the thickness of the stone. The other red line BD is the offset of the pivot. If we fix the slope of line CD to that of line AB (not drawn, representing the case of a zero-thickness stone) the two lines AC and BD can only be the same length if angle ∠BDC is 90 degrees. If it is not, as in the illustration, BD must be longer than AC.
THANK YOU.
I do appreciate your reply, and do agree; that if you change stone thickness (increase AC) that using the collar-stop method to equally increase BD, that CD and AB will not be parallel (applied bevel angle will change), and there will be a slight change in applied angle (edge bevel angle), but have NOT noticed any issue with using this method over a number of years use in practical application of the collar-stop.
You are correct ! Thank you.
Test Example-1:
I typically run my EdgePro with the table level (adjustable PanoVise style base).
I just set up my EP at typical sharpening angle of 15dps using one of my MoldMaster stones on aluminum blank (6.12mm combined thickness stone & blank).
∠BDC is very close to 90°.
Using collar-stop method of varied-stone-thickness adjustment to make a VERY large change (greater than anything I have ever done over the years), from 1 stone and blank to 4 stones on blanks (a ~4x change) made a 0.1° change to 15.1° of edge applied angle. Considering this 0.1° inaccuracy is the result of a change much greater than I ever do, I would still stand by my comment "
the use of the stop collar does effectively eliminate the issue of multiple stone thicknesses "
The 'nut' though (the fruit what I have learned here) ..., is I need to remember for some day in the future when I significantly raise the applied angle (∠BDC significantly far from 90-degrees).
Test Example-2:
I just set up my EPC at a non-typical sharpening angle of 30dps using one of my MoldMaster stones on aluminum blank (6.12mm combined thickness stone & blank).
∠BDC is very noticeably less than 90-degress.
Using collar-stop method of varied-stone-thickness adjustment to make a very large change (greater than anything I have ever done over the years), from 1 stone and blank to 4 stones on blanks (a ~4x change) made a 0.3° change to 29.7° of edge applied angle. Considering this 0.3° inaccuracy is the result of a change much greater than I ever do, I would still stand by my comment "
the use of the stop collar does effectively eliminate the issue of multiple stone thicknesses "
Result:
One might argue inaccuracy in both my examples is the result of tolerance stacking (multiple stones stacked ...), but I believe Mr. Wizard is correct (technically).
I suppose I could modify my original statement as follows
in practical application "the use of the stop collar does effectively eliminate the issue of multiple stone thicknesses".
Bottom line, once a stone has been indexed to my table the collar stop does what it is intended to do, is a great $3 accessory for the system, and is trustworthy when used correctly.
PS: I do realize there is a bit of up/down slop (0.35° measured) in the hinge/slide between Pivot Mast & Stone Arm, and understand I was eliminating this slop in my two examples above effectively negating this variable.
Thanks again, appreciate the enlightenment on the subject ;-)
