WSKO blade grinding angles.

Did you try emailing worksharp? They are pretty good at responding

 

Yes, the angles are in DPS.

Only our erstwhile forum-mate Gaston, would want a sharpening system that would get the edge to 15 deg. inclusive.

 

Hi,
See also calibration-results-from-my-wsko-bga-actual-apex-angle-vs-tool-setting.1528884 cause 17 degree setting doesnt actually result in 17degrees per side, more like 30-34degrees...

Hi,
Have you ever tried a 7dps edge?
It cuts a lot better than 15dps edge, anything higher than 15dps is for axes*
I think anybody who tries it would want it.

If you buy a cheap knife (mora and cheaper ) or machete... you're lucky if you get 10dps edge, but then they're so thick cause have no primary grind,
so as a first step to fine tuning blade, you might start with a regrind to 7dps.

This sharpening sub forum is full of people who appreciate 7dps edges, for example to cut grass or cardboard
FortyTwoBlades: In my experience with scythe blades, which are ground at only 7-9° per side

See also whats-the-lowest-functionable-angle-by-steel-type.1587190/#post-18129004****

In my opinion,
Any knife sharpening machine that doesnt have a 7dps setting .. cause the clamp is fat and what not ... is ridiculous.
And this is ridiculous advertisement Infinitely Adjustable Sharpening 17 degrees to 30 degrees
Oooh wow "infinite" increments for axe sized angles****

This is your competition 3-14dps/7-22 degrees per side
wicked-edge-microbevels.1592543/#post-18221885
/
https://imgur.com/a/g50oXTv
The final apex the $2-$3 snap together knife sharpener, angles only go from 3-14dps/7-22 degrees per side cause its for knives

 

I have a couple home made guides that are at 7 dps.

 

All that math is too complicated, I just throw my knife into the ground until its sharp again

 

I don't believe the link you posted is accurate. Something is clearly wrong, as other posters there are getting edges that are very very close to the indicated angle. Also, he seems to be reporting included angle (total angle of both sides), whereas the tool is marked as degrees per side (one side, not two).

The biggest variable we don't know about in that test is how the blade was being held (yes I know it was a steel strap and not a real blade). If it wasn't perfectly parallel to the surface that the tool was resting on, then the angle measurement really doesn't mean much.

Brian.

 

Hi,
Got link to other posters , somebody who posted pics of measured angles?
If you have a link to share it would make a good reply in that thread.
Asking about verticality/parallelness would also make a good question



If you keep reading, Cyrano says

For the reasons described above, I don't know if my results will have good predictive power for your system.

For this thin blade, the offset between the tool setting and what I measure as the inclusive apex angle is 3 degrees.
For this thicker blade, the offset between the tool setting and what I measure as the inclusive apex angle is 6 degrees.
... perhaps a user could combine my results with one or two data points of their own to create a personalized model which would have quantitative predictive power for them.


I see nothing "clearly wrong" , only a totally dead on balls accurate report

 

See Post #8 in the thread you linked.

...and will you please at least acknowledge that the original poster in that thread is measuring INCLUDED ANGLE and not degrees per side? You make it sound like the BGA is off by a factor of 100% according to this guy's measurements. His measured angles should be DOUBLE the indicated angle since he is not measuring degrees per side.

Brian.

 

See this thread for the rest of the story.

 

Hi,
Thanks, I've already seen that one and liked it.

Well,
Remember the dot dot dot from my post that you quoted?
Thats an unfinished thought/sentance ,
Thats the part that invites anybody reading
to finish the thought,
to click the link ,
read the details,
and finish the thought,
to see whats per side and whats inclusive.


The BGA can indeed be off by 100% ( a factor of 2, multiply by 2 )
thats clear from reading the original thread,
and crystal clear from the followup Offset between WSKO apex angle and BGA setting is now understood
Find 17 degree per side setting on the chart, and see the resulting angle can be over 30 degrees per side

 

Excuse me if I'm extremely skeptical about those results. Maybe they are accurate. Maybe they aren't. Maybe Cryano is not holding his test samples exactly parallel to the base of the BGA, which is required in order to produce accurate angles. This is a machine that uses a human to hold the work, and is therefor subject to the limits and perceptions of the human. What seems level by eye might not be all that level.

Or perhaps the introduction of SQUARE stock to a flexible belt massively changes the grinding angle due to the geometry. Testing on blades that already have actual edge bevels would seem to be a more realistic test.

I find it very very hard to believe that WorkSharp would produce a product with enormous errors in it's indicated angle. Even if the error is "only" 50% and a 17 degree per side edge becomes 25.5 degrees per side, that doesn't seem reasonable to me.

Maybe I'm wrong about all this and the BGA is fundamentally flawed and inaccurate. But I don't think so.

Brian.

 

Brian,

No apologies needed. Skeptical is good! Good scientific work stands up to peer review. As I've seen quoted on another forum, "One person sharpens another."

Without doubt, this factor can and does contribute variation in this experiment. However, the goodness of fit for the linear regressions provides strong evidence that the total variation introduced by this factor (in combination with all others) is insignificant.

I agree: the geometry of the thick bar stock differs from that of the actual knife edges which have a primary bevel. I believe the important factor here is not the cross-sectional shape of the blade (rectangular for the bar stock vs. triangular for the typical knife), but the thickness of the blade stock at the point of contact with the belt, as this is the only point on the blade's cross-section which determines the amount of belt deflection.

I also agree that testing on blades which have a primary bevel is a more realistic test because it puts the test in a regime of blade stock thickness which is typical of common uses, and in which the offset between setting and results is less significant.

As I see it, there are no "errors" in the WorkSharp product; rather, it is remarkably accurate and precise. For thin blade stock, there is no offset at all: dial in 15 dps and you'll get 15 dps.

Theory proposes, experiment disposes.

I've put forth experimental data which are repeatable, reproducible, self-consistent, and which fit a plausible physical model. To my mind, that forms a reasonable explanation.

Again, we're not debating philosophy here, we're attempting to do science. I'd be delighted if any new data are presented which offer more insight into this phenomenon.

Again, these results do not support the assertion that the BGA is inaccurate; quite the opposite. The BGA is demonstrably accurate and precise.

Whether or not the BGA is flawed is a matter of opinion. In my opinion, the BGA is an excellent tool, capable of producing sharp edges on almost anything quickly and easily. As with all tools, one must understand how it works in order to get the most value from it.

Tony

 

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Cyrano,

Thanks for the thoughtful reply. For purposes of this thread, I'm not super interested in all of the details of your findings, though they are interesting for sure. I'm mostly interested in whether or not the BGA is accurate, or at least close. The claims made earlier in this thread indicate that the BGA is wildly inaccurate. My replies were based upon that.

For this particular thread this is all I need to know. It seems the BGA is just fine for sharpening blades and produces consistent results that correspond to the indicated angle.

Thanks for the clarification.

Brian.