Grinding software upgrade is coming

[Jan]

In the new thread started today by JVH it is discussed in details with additional drawings. https://forum.tormek.com/index.php?topic=4110.0

I have attached the simple prof. Verhoeven formula relating the bevel (tangent) angle and the chord angle.

Jan

[cbwx34]

Or may be not...
So the enhancements that wootz has made to his software is in effect calculating the chord angle using the target grind angle, which means the angle at the edge is more acute. That being the case the finer edge angle goes some way to explaining how wootz is achieving lower BESS scores with the software tweaks, improvements I might add are probably at the expense of edge retention.
...more muddy water?

That's probably reading too much into it... at least I don't think it would be all that significant.

FWIW... I purchased wootz updated app, and ran some numbers, comparing it to both Dutchman's old and new formulas.  Here's a quick sample...



... if anything, things are probably starting to line up a bit better between calculators?  (I didn't double check it, and it would be interesting to see, for example a comparison of angles setting the USB with wootz app, then "reversing" it to see the angle in Dutchman's New Formula, but in most cases, doesn't seem to be that much).

Also, jvh... you brought this up earlier...

...
Last at not least your results in this trial sharpening (12° gave + error , 20 ° gave - error) don't make a sense. Result seems to me inconsistent and I cannot simulate/verify it.
...
jvh

... I noticed the same thing when I was doing testing before, I think between the old and new formulas.  I remember doing most of my testing at 15°, because it seemed "neutral".  I don't know why (i'll leave that for you smarter people), but I don't think it has anything to do with wootz's revision.

[cbwx34]

In the new thread started today by JVH it is discussed in details with additional drawings. https://forum.tormek.com/index.php?topic=4110.0

I have attached the simple prof. Verhoeven formula relating the bevel (tangent) angle and the chord angle.

Jan

But, (mostly for clarification), the calculator sets the angle based on the tangent at the very edge, right? (So, doesn't it account for this? Basically what jvh said earlier...)

[Josu V]

Hello everyone.
The following comment is not to solve the "problem" about the thread of discussion, but I think all points of view are interesting.

I have no advanced mathematical knowledge and it is impossible for me to offer a qualified point of view, but I have the other part of the equation: the practice.

I received the actualizated app of Wootz and I have used it in (about) 40 knives including the day of today.
This knives been between 0,4mm to 2,5mm thicknes behind the edge.
Absolutly all the knives finished in target angle. The comprobation of the angle was with Catra Laser Protractor.
I know the Catra have a tolerance, but the ressults have been clarifiers in my opinion.

Nothing more. I would like to have enough level in order to clarify this problem, but only can offer this.

Regards

[Jan]

Ken, have you also made allowances on your jig for setting an alternative honing angle on knives as detailed in Wootz's book on deburring?

Good question, John. Yes, the kenjig concept allows for setting an alternative honing angle on knives.

First alternative which was mentioned by Ken is making honing kenjigs with distances for different deburring stages.

Second alternative is even simpler. When the kenjig for projection length of 139 mm sets the USB for honing 15 degree bevel angle then one full revolution of the knife jig stop's changes this angle by some 1.6 degrees. If you e.g. intend to hone this blade at edge angle of 15.4 degrees you simply rotate the jig stop by 90 degrees.

This example is valid for T7 and T8.

Jan

[Jan]

In the new thread started today by JVH it is discussed in details with additional drawings. https://forum.tormek.com/index.php?topic=4110.0

I have attached the simple prof. Verhoeven formula relating the bevel (tangent) angle and the chord angle.

Jan

But, (mostly for clarification), the calculator sets the angle based on the tangent at the very edge, right? (So, doesn't it account for this? Basically what jvh said earlier...)

Yes, CBWX, you are right!

Jan

[cbwx34]

In the new thread started today by JVH it is discussed in details with additional drawings. https://forum.tormek.com/index.php?topic=4110.0

I have attached the simple prof. Verhoeven formula relating the bevel (tangent) angle and the chord angle.

Jan

But, (mostly for clarification), the calculator sets the angle based on the tangent at the very edge, right? (So, doesn't it account for this? Basically what jvh said earlier...)

Yes, CBWX, you are right!

Jan

Thanks!

Hello everyone.
The following comment is not to solve the "problem" about the thread of discussion, but I think all points of view are interesting.

I have no advanced mathematical knowledge and it is impossible for me to offer a qualified point of view, but I have the other part of the equation: the practice.

I received the actualizated app of Wootz and I have used it in (about) 40 knives including the day of today.
This knives been between 0,4mm to 2,5mm thicknes behind the edge.
Absolutly all the knives finished in target angle. The comprobation of the angle was with Catra Laser Protractor.
I know the Catra have a tolerance, but the ressults have been clarifiers in my opinion.

Nothing more. I would like to have enough level in order to clarify this problem, but only can offer this.

Regards

I think we're all pretty close... consistency can be just as (if not more important) than accuracy, so no matter what one decides to use, stick with it!

Sometimes I think we're splitting hairs, in the hopes of splitting hairs. 

[wootz]

Instructions on our software update have been emailed.
If we missed someone, it means we do not have your email on records - please email us a proof of purchase of the original applet, and we will email you a promo code to install the updated applet free of charge.

Feedback from Spain:

[Jan]

FWIW... I purchased wootz updated app, and ran some numbers, comparing it to both Dutchman's old and new formulas.  Here's a quick sample...

CB, thanks for spending money for purchasing the updated app. It is of key importance for our discussion here. The differences are large! Please if you find some time make similar comparison for the honing wheel also. Thanks in advance.

Jan

[jvh]

Hello everyone.
The following comment is not to solve the "problem" about the thread of discussion, but I think all points of view are interesting.

I have no advanced mathematical knowledge and it is impossible for me to offer a qualified point of view, but I have the other part of the equation: the practice.

I received the actualizated app of Wootz and I have used it in (about) 40 knives including the day of today.
This knives been between 0,4mm to 2,5mm thicknes behind the edge.
Absolutly all the knives finished in target angle. The comprobation of the angle was with Catra Laser Protractor.
I know the Catra have a tolerance, but the ressults have been clarifiers in my opinion.

Nothing more. I would like to have enough level in order to clarify this problem, but only can offer this.

Regards

Hello,

thank you for your report. Can you give us more information to get a better overview?

Did you check angles also when you were using previous version of app and did you notice some difference between old and new results?

Which angle did you grind typically and what was overal range of angles which you grinded on last 40 knives?

Regards
jvh

[cbwx34]

FWIW... I purchased wootz updated app, and ran some numbers, comparing it to both Dutchman's old and new formulas.  Here's a quick sample...

CB, thanks for spending money for purchasing the updated app. It is of key importance for our discussion here. The differences are enormous! Please if you find some time make similar comparison for the honing wheel also. Thanks in advance.

Jan

If you mean the FVB app... I don't have the ability to test that.  (It requires his FVB).

I went ahead and did a comparison of the earlier chart... answering "what would the angle be in Dutchman's new formula, using the USB height set in wootz new app (the angles are in parenthesis)...



... IMO, (in this limited set), most differences aren't that big... the exception being the 2mm thickness at 10°.  (WD:250 PD:140).  That one is 2° difference.  Even comparing it to the "old formula" it's significant. (That should be large enough to show up in an actual test).  But for most knives, the difference is not that significant... everything else is less than 1°.  (This is all theory at this point on my end... no motor running).  (Hopefully, I did it right). 

I'm thinking most of the "checks" aren't accurate enough to validate one way or the other...  but either way, it's better than the AngleMaster! 

[Jan]

CB, thanks for your analysis which shows that the maximum error for the limited input data set is some 2⁰ while the majority is probably smaller than 1⁰.

You are a benevolent judge. This benevolence may be understood with the explanation that changing bevel angle by 1⁰ will not dramatically change the cutting performance of the blade.

The major concern is that +/-1⁰ error in bevel angle and +/-1⁰ error in honing angle may be fatal for edge deburring. Having those errors it is not possible to reliable setup an alternative honing angle on knives as detailed in the booklet on deburring. For this reason I have asked you to kindly include also the honing wheel diameter in your table.

Jan

[Josu V]

Hello,

thank you for your report. Can you give us more information to get a better overview?

Did you check angles also when you were using previous version of app and did you notice some difference between old and new results?

Which angle did you grind typically and what was overal range of angles which you grinded on last 40 knives?

Regards
jvh

Yes.
Exactly was 38 knives.
10 knives was sharpened at 17º  (butcher knives)
25 knives was sharpened at 15º (kitchen knives)
3 Knives at 20º (two folden knives and one knife. All for Hunting
All in DPS.

With the old app, I did not verified all knives, but sometimes I finded an error of +1º at maximum. I have not exact notes of the final angle of all of knives, but always was higher angle than target.
Sharpened with SG-250 (actually 227mm of diameter), DF-250 and DE-250

This is all the information that I can offer.

Regards

[cbwx34]

CB, thanks for your analysis which shows that the maximum error for the limited input data set is some 2⁰ while the majority is probably smaller than 1⁰.

You are a benevolent judge. This benevolence may be understood with the explanation that changing bevel angle by 1⁰ will not dramatically change the cutting performance of the blade.

The major concern is that +/-1⁰ error in bevel angle and +/-1⁰ error in honing angle may be fatal for edge deburring. Having those errors it is not possible to reliable setup an alternative honing angle on knives as detailed in the booklet on deburring. For this reason I have asked you to kindly include also the honing wheel diameter in your table.

Jan

Like I said, the honing setup is separate, I can't provide that info.

If the "error" is consistent, it would cancel out (or hopefully favor a higher angle in honing).   (I've always said "consistency").

I mainly came here to get a better understanding of the section in Dutchman's book (that I'm now satisfied with).

Here's the way I see it, and why I published the chart.  For the most part, other than the 2mm thickness (which that thickness behind the edge would cause other issues anyway...), I don't see a glaring difference... and probably overall pretty consistent.  Most Tormek sharpeners aren't going to get caught up in the decimals... frankly "Sharpie accuracy" probably suffices.  I do think there may be some issues, or at least some questions with this approach, most have which already been presented, but wootz doesn't seem interested in working this out, so at this point, it's probably not worth it to belabor the issue.  My .02. 

[Dutchman]

...
but either way, it's better than the AngleMaster! 

Thank you for testing and verifying that.
But the most important thing about this method is that the setting is also much faster if you don't use that computer.