Grinding angle thoughts

[Ken S]

I am grateful that we have forum members skilled in mathematics. Starting with Dutchman
(Ton Nillesen) in 2014, our forum members have significantly advanced bevel angle setting with the Tormek. The kenjig, my own small part in this, is based on Dutchmańs work. I am also grateful to Jan, who has both the mathematical skill to work very precisely, and the wisdom to realize when small erors are insignificant for practical purposes, a rare combination of abilities.

In designing the kenjig, I gave consistent repeatability and efficient set up time priority over exactness. I standardized on fifteen degrees per side bevel angles. ¨Fifteen degrees¨ may actually be 14.7degrees or 15.3 degrees, however, all of the bevels will be a consistent. repeatable angle. Some may consider me a heretic or just sloppy, however, I believe my method provides mmore than adequate accuracy.

I am not opposed to progress. I have the Knife Grinders applet loaded on my laptop and on my ipad. I will not hesitate to use it for unusual situations. I also purchased a Front Vertical Base from Knife Grinders and look forward to using it.

In setting up the kenjig, I standardized on 15 degree bevel angles, 139 mm Projection, and 80 mm Distance between the support bar and the grinding wheel with 250 mm diameter for the grinding wheel. Eventually, I will need to adjust the Distance to compensate for grinding wheel wear, unless I switch to diamond wheels for knife sharpening. The Distance is only set once in a sharpening session, whereas the Projection must be matched with each knife, therefore, I plan to only alter the distance with wheel wear.

I have seen many advances in the Tormek and technique since I first purchased my T7 in 2009, both from Sweden and from the Forum. I eagerly anticipate many more advances. If I was younger and attached at the hip to my smart phone, I would probably be using one or more of the computer angle setting apps regularly. I will try to keep up with the changes, although it is hard not to remain at rest since Dutchmańs original tables have served me so well.

I am most pleased to see that Dutchman has not just sat back on his laurels and has continued to update his work. Between Dutchman, Jan, CB, Wootz and Herman, we have a real dream team. I look forward to see what our team, in addition to other members and Team Tormek will produce in this coming year.

Ken

[John_B]

I think you will like the results when using the FVB. Setting the honing angle per Wootz's recommendations in his book for honing the final sharpness surpasses anything I can do freehand.

[Ken S]

Thanks, John. I appreciate your thoughts and experience.

I must raise the priority of learning my FVB. It seems a logical extension of my standardized kenjig technique.

Ken

[Jan]

Ken, your standardized Kenjig technique can be applied to FVB also. For both, sharpening and honing. It works for all Tormek machines and also for bench grinders with an USB.

Ken, you are correct that a knife with bevel angle 14.7⁰ or 15.3⁰ performs almost identically. Where we need high accuracy is setting the honing angle by some 1.5⁰ higher than the bevel angle. When the bevel angle was 15⁰ and the honing angle should be 16.5⁰ than an accuracy of +/-1⁰ is not fully sufficient. We have to achieve an accuracy of +/-0.5⁰ because otherwise we cannot follow Wootz's recommendations. I agree with John that such a honing cannot be done freehand.

Jan

[Ken S]

Well stated, Jan. You keep me thinking. Thank you.

Ken

[Dutchman]

Ken, you are correct that a knife with bevel angle 14.7⁰ or 15.3⁰ performs almost identically. Where we need high accuracy is setting the honing angle by some 1.5⁰ higher than the bevel angle. When the bevel angle was 15⁰ and the honing angle should be 16.5⁰ than an accuracy of +/-1⁰ is not fully sufficient. We have to achieve an accuracy of +/-0.5⁰ because otherwise we cannot follow Wootz's recommendations.
...

No, that is far too cumbersome.
After grinding, you have to shorten the distance 'A' in my figure 4.1 by 1 mm and then you have the correct setting for honing.
You can also read that in my tables.

You do not need the FVB. Only the Kenjig and a ruler.

[brute]

Is not the angle, for honing & deburring, depending on the (type) of knife steel?

[Ken S]

Interesting. We have a saying in English, "Two wrongs do not make a right." (not to be applied with positive and negative numbers) In this case, two rights can make a greater right.

While my math skills are not well honed, my appreciation for math is. I find the pioneering work by Dutchman, Jan, Wootz and CB amazing. This fine pioneering work has certainly advanced sharpening.

On the other hand, my simple technique based on Dutchman's tables has served me well for several years. Shortening distance A by one millimeter is easily done by placing a second pencil line one millimeter shorter than my 139mm line on my kenjig.  I believe this will serve my simple needs. I like having the applet and FVB in reserve for unusual situations.

I think a well trained sharpener should know both methods.

Ken

[RickKrung]

...snip...
After grinding, you have to shorten the distance 'A' in my figure 4.1 by 1 mm and then you have the correct setting for honing.
You can also read that in my tables.

You do not need the FVB. Only the Kenjig and a ruler.

That is a great reminder, that the angle can also be changed by altering the projection length.  It also seems like a very workable approach, IF the wheel diameters are the same (something that would happen extremely rarely?).  Given that the honing wheel is not the same diameter as our grinding wheels, it seems to me there still needs to be a method of setting the honing angle at precisely the sharpening angle - and then - change the projection to increase the angle, in your example by 1 mm. 

This seems particularly true if one is doing the grinding on the vertical USB rather than the horizontal.  I do not know if this example is based on using the horizontal USB, leaving it in place and simply changing the projection distance and moving from the grinding wheel to the honing wheel.  I am struggling to see how it works with a changing grinding wheel diameter and a fixed diameter honing wheel, even on the horizontal USB. 

Clearly, I am missing something.  Could someone please clarify this for me? 

Thanks,

Rick

[Jan]

Ken, you are correct that a knife with bevel angle 14.7⁰ or 15.3⁰ performs almost identically. Where we need high accuracy is setting the honing angle by some 1.5⁰ higher than the bevel angle. When the bevel angle was 15⁰ and the honing angle should be 16.5⁰ than an accuracy of +/-1⁰ is not fully sufficient. We have to achieve an accuracy of +/-0.5⁰ because otherwise we cannot follow Wootz's recommendations.
...

No, that is far too cumbersome.
After grinding, you have to shorten the distance 'A' in my figure 4.1 by 1 mm and then you have the correct setting for honing.
You can also read that in my tables.

You do not need the FVB. Only the Kenjig and a ruler.

Ton, it is misunderstanding. When I have spoken about honing, I meant another wheel not the wheel used for grinding. Typically the leather honing wheel which has of course different diameter!

Ton, your example with shortening the projection length by 1 mm is unsuitable. Consider that we sharpened a blade using a kenjig designed for 15⁰ bevel angle, projection length 139 mm, grindstone with diameter 250 mm. When we stay with the same grindstone and the same USB position and only shorten the projection length to 138 mm we will get a bevel angle some 15.6⁰. This is not large enough honing angle for reliable deburring.

Jan

[Jan]

That is a great reminder, that the angle can also be changed by altering the projection length.  It also seems like a very workable approach, IF the wheel diameters are the same (something that would happen extremely rarely?).  Given that the honing wheel is not the same diameter as our grinding wheels, it seems to me there still needs to be a method of setting the honing angle at precisely the sharpening angle - and then - change the projection to increase the angle, in your example by 1 mm. 

This seems particularly true if one is doing the grinding on the vertical USB rather than the horizontal.  I do not know if this example is based on using the horizontal USB, leaving it in place and simply changing the projection distance and moving from the grinding wheel to the honing wheel.  I am struggling to see how it works with a changing grinding wheel diameter and a fixed diameter honing wheel, even on the horizontal USB. 

Clearly, I am missing something.  Could someone please clarify this for me? 

Rick, they are three dimensions which uniquely define the bevel angle of blade centred in Tormek knife jig:
1)   Wheel diameter
2)   Projection length
3)   Wheel surface – USB distance

It works for both, horizontal and vertical USB. This means that the bevel angle will be the same when you change the grinding direction while keeping the three dimensions the same.
Jan

[RickKrung]

...snip...
Rick, they are three dimensions which uniquely define the bevel angle of blade centred in Tormek knife jig:
1)   Wheel diameter
2)   Projection length
3)   Wheel surface – USB distance

It works for both, horizontal and vertical USB. This means that the bevel angle will be the same when you change the grinding direction while keeping the three dimensions the same.
Jan

Number 3 is my incorrect assumption.  I was speaking from the perspective of using the USB height from the case or USB sleeve (horizontal USB position), not the distance from the wheel surface to the stone/wheel.

Of course, now it makes compete sense.  Knew I was missing something

Causes me to think maybe I should take a closer look at using that distance rather than to the case. I'm sure there are issues with that as well.  Don't know where the expression originates, but...  "there are no free lunches". (and I realize that contrarily, there are free lunches, in some places/circumstances)

Thanks,

Rick

[Jan]

Rick, what I like on this forum is permanent repetition of thoughts concerning sharpening. Often it is sufficient to look at it from slightly different angle and we start to see it in a broader context. It deepens the understanding of the whole community.

Rick, the wheel surface – USB distance is much more universal parameter than the USB height measured from Tormek housing. Wheel surface – USB distance does not depend on the type of grinding machine we use and it is applicable for bench and belt grinders also.

Jan

[RickKrung]

Rick, what I like on this forum is permanent repetition of thoughts concerning sharpening. Often it is sufficient to look at it from slightly different angle and we start to see it in a broader context. It deepens the understanding of the whole community.

Rick, the wheel surface – USB distance is much more universal parameter than the USB height measured from Tormek housing. Wheel surface – USB distance does not depend on the type of grinding machine we use and it is applicable for bench and belt grinders also.

Jan

Yes, I agree, on both counts.  The latter is really just dawning on me, perhaps partially because I've struggled with use of the USB on two other platforms besides the Tormek.  It is clear to me now just how universal the distance between the USB and wheel OD is and how that can hugely simplify angle setting, across all the platforms.

I'm excited to explore this new understanding.  It will be a bit before I can really get in to it.  Family arrives tomorrow for Christmas.  I have a lot to do yet to get ready and they will be here for almost a week.

Rick

[cbwx34]

Rick, what I like on this forum is permanent repetition of thoughts concerning sharpening. Often it is sufficient to look at it from slightly different angle and we start to see it in a broader context. It deepens the understanding of the whole community.

Rick, the wheel surface – USB distance is much more universal parameter than the USB height measured from Tormek housing. Wheel surface – USB distance does not depend on the type of grinding machine we use and it is applicable for bench and belt grinders also.

Jan

Yes, I agree, on both counts.  The latter is really just dawning on me, perhaps partially because I've struggled with use of the USB on two other platforms besides the Tormek.  It is clear to me now just how universal the distance between the USB and wheel OD is and how that can hugely simplify angle setting, across all the platforms.

I'm excited to explore this new understanding.  It will be a bit before I can really get in to it.  Family arrives tomorrow for Christmas.  I have a lot to do yet to get ready and they will be here for almost a week.

Rick

Let the awakening begin...