Not sure if this is news to the Tormek community, but actual honing wheel LA-220 diameter is 215 mm.
If you set your honing angle at the 220 mark that is in bold on the AngleMaster, you will inevitably round the edge.
Correct is setting it at 215 mark - as shown by the red line on the photo:
(http://knifegrinders.com.au/photos/AngleMaster.JPG)
Thanks Vadim.
I should have added a table for 215mm, but I supposed that the 220mm was correct. >:(
>:( I kept wondering why BESS score worsens after honing my knives, till I questioned the leather wheel diameter.
Had to redo my applet for the frontal vertical base honing angle because of that.
BTW I have it now for Mac as well.
Not that i think you need help with calculations :), yet let me know if you want it.
Wootz, your observation is correct! Diameter of my honing wheel is 215 mm also.
Based on my calculations, ignoring this fact will cause that we are honing a bevel angle changed by some 1.3°. (I have assumed projection length of 139 mm and 15° bevel angle.). ;)
Jan
Thank you, Jan, I've been waiting for your estimate, I knew it's coming.
My tests show that the edge can survive burial into the honing wheel up to 0.5 degrees, but from +0.6 degrees it loses sharpness dramatically.
Not being a mathematician, I note that Dutchman's tables for a 15° bevel and 85mm Distance (between the universal support and the grinding wheel) shows a Projection of 141mm with a 220mm diameter grinding wheel and a 135mm Projection at an 80mm Distance. Since I standardized on 139mm Projection with the kenjig, I would make a kenjig with a Distance setting groove of 83.5mm, actually a thin reading (like 83.4). The same Distances with the 210mm diameter chart show 139 and 134mm Projections. I would just split the difference, and make a kenjig for 215 mm diameter at approximately 84.2mm. I am quite sure even this approximation is beyond the accuracy of any measurement tool graduated in one degree increments.
Unlike a kenjig made for a gradually consumable conventional grinding wheel, the Distance should not vary over time with a leather honing wheel.
What puzzles me with this is that the smaller Distance reading for 220mm diameter would tend not to polish the very edge of the blade. Using a larger Projection number (from a smaller diameter table) would tend to add a slight micro bevel (secondary bevel). Although I have not tested it, it would seem logical that the reading from the 220mm chart would have no effect on the BESS readings, as the Distance would in effect be designed for a slightly smaller bevel angle and the edge barely touched.
I can't believe that the Tormek engineers would mismeasure the diameter by 5mm. There must be a logical reason for the difference. It would be interesting to know.
Ken
Quote from: Ken S on September 13, 2017, 12:38:00 PM
Not being a mathematician, I note that Dutchman's tables for a 15° bevel and 85mm Distance (between the universal support and the grinding wheel) shows a Projection of 141mm with a 220mm diameter grinding wheel and a 135mm Projection at an 80mm Distance. Since I standardized on 139mm Projection with the kenjig, I would make a kenjig with a Distance setting groove of 83.5mm, actually a thin reading (like 83.4). The same Distances with the 210mm diameter chart show 139 and 134mm Projections. I would just split the difference, and make a kenjig for 215 mm diameter at approximately 84.2mm. I am quite sure even this approximation is beyond the accuracy of any measurement tool graduated in one degree increments.
Ken, you are correct, you have used a linear interpolation method which is believed that it was used by Babylonian astronomers. Currently it is used in all modern computer graphics processors. ;)
The exact Distance is 83.9 mm using the Dutchman's approach for 215 mm wheel diameter, 15° bevel angle and 139 mm projection length.
Jan
Quote from: wootz on September 13, 2017, 12:37:29 PM
Thank you, Jan, I've been waiting for your estimate, I knew it's coming.
My tests show that the edge can survive burial into the honing wheel up to 0.5 degrees, but from +0.6 degrees it loses sharpness dramatically.
Wootz, you are welcome! :)
Your observations concerning abrupt loss of edge sharpness are very interesting for me. Have you observed the same behaviour also when honing "chisel grind" blades buried into the honing wheel?
Jan
Quote from: Jan on September 13, 2017, 03:15:57 PM
Quote from: wootz on September 13, 2017, 12:37:29 PM
Thank you, Jan, I've been waiting for your estimate, I knew it's coming.
My tests show that the edge can survive burial into the honing wheel up to 0.5 degrees, but from +0.6 degrees it loses sharpness dramatically.
Wootz, you are welcome! :)
Your observations concerning abrupt loss of edge sharpness are very interesting for me. Have you observed the same behaviour also when honing "chisel grind" blades buried into the honing wheel?
Jan
This was a full-range study (unrelated to the LA-220), will be published in the US Sharpeners' Report in their December issue. I will send you a complimentary copy then.
For now can only show you the chart of BESS score as function of the Honing Angle - treat as a spoiler :P
(http://knifegrinders.com.au/dropbox/chart.bmp)
Hi all,
Very interesting topic.
Sharpening a chisel at 25-30 degrees the difference between setting the diameter on 215 mm or 220 mm is 0.46° when using the WM-200 angle-master.
Noticeable is that the angle will be less on 215 mm than 220 mm.
There are some things needed to be considered measuring this. Using stones to hone with will result in a different result than with a leather honing wheel.
The leather is so much softer than a stone that it will not round the edge. To round an edge you need to have much more angle difference than 1 degree.
The idea used by us and most manufacturers is that a increased polish on the tip will make the edge finer.
For knives this is common. You can have a original grind at 28 degree and a polished edge at 2-3 degrees. Almost like a secondary edge but hardly noticeable.
A chisel will not get a less sharp edge if the back is 100% plane. A rounded edge on a chisel is mostly because the back is not flattened correctly.
The LA-220 setting on the Angle master is necessary to get the burr of the edge. If we would have a setting of 215 mm the burr would be hard to hone away. The leather is very soft and the measurements could maybe be transferred to a stone but not on a leather honing wheel.
Honing is an issue where I think that practise makes all the difference. Using the jig to hone a chisels edge but free-hone the back can be tricky. It's easy to round the back and that's the issue in most cases. Setting the anglemaster at 220 as our design is, will not be the reason for a rounded tip.
Sincerely,
Stig
Quote from: wootz on September 14, 2017, 01:11:30 AM
This was a full-range study (unrelated to the LA-220), will be published in the US Sharpeners' Report in their December issue. I will send you a complimentary copy then.
For now can only show you the chart of BESS score as function of the Honing Angle - treat as a spoiler :P
(http://knifegrinders.com.au/dropbox/chart.bmp)
Wootz, thank you very much for your additional info from your paper in print. I am really eager to read the whole study, especially your discussion of the interesting results.
Jan
Quote from: wootz on September 14, 2017, 01:11:30 AM
This was a full-range study (unrelated to the LA-220), will be published in the US Sharpeners' Report in their December issue. I will send you a complimentary copy then.
For now can only show you the chart of BESS score as function of the Honing Angle - treat as a spoiler :P
WOW! That is very convincing! Thanks. Are you going to post that publication here too? I would love to have a copy of it.
Stig, thank you for your statement to this interesting topic. Much appreciated! :)
Based on my calculations for a knife blade mounted in a knife jig at 15 degrees bevel angle and 139 mm projection length the difference between setting the diameter on 215 mm or 220 mm is 1.3 degrees.
Based on my calculations for a chisel at 25 degrees mounted with protrusion 50 mm in the SE-76 jig the difference between setting the diameter on 215 mm or 220 mm is 0.42° which is in compliance with your figure. Sorry, I made an error when I was simulating the angle setting by the 220/215 mm procedure using my older Excel scripts.
Regards
Jan
Jan,
"Based on my calculations for a chisel at 25 degrees mounted with protrusion 50 mm in the SE-76 jig the difference between setting the diameter on 215 mm or 220 mm is 0.42° which is in compliance with your figure."
We checked some different protrusions and the result was between 0.01-0.05° which is not noticeable.
I would say we are down to really nerdy info now :-)
Of coarse there is a difference with a knife and a chisel.
It would be very interesting to know how the knifes are honed. Is the result the same when using the knife jig or honing freehand?
Best,
Stig
Stig, you are correct again! :) The difference between setting the diameter on 215 mm or 220 mm when using the WM-200 angle-master shows only weak dependence on chisel protrusion.
Regards
Jan
Stig's post reminds me of a technique I learned from Ernie Conover many years ago. Ernie kept a very fine ceramic stone with his Tormek. In a long out of print video, Ernie demonstrated using the leather honing wheel to polish the bevel of a chisel. Then, instead of using the leather honing wheel freehand, he polished the back freehand on flat ceramic stone. As long as the chisel was carefully placed flat on the ceramic stone, no rounding would occur. By leaving the chisel in the jig, the sharpener could alternate between polishing the bevel and the back with both the accuracy of the jig and the solid support of the ceramic stone for the back.
I agree with Stig about the importance of practice. The careful use of jigs can speed up the process of edge mastery for those of us (including me) whose skill is developing. However, a jig is not a full substitute for focused practice. I have no doubt that very skilled Tormekers can produce a polished flat back with the round Tormek wheel. I can do it to a level I find adequate for most work. For demanding work, I still prefer the jig and ceramic stone method.
One of the intriguing aspects of sharpening is how really sharp keeps getting sharper. We have benefit of both Tormek's decades of experience, plus the ideas and experience of many members. When I first started with this forum, most of the topics were what we would call "frequently asked questions", generally answered in one reply by thee moderator, Jeff Farris. We still have and welcome those questions. We also have an emerging number of very interesting deeper topics, such as this topic. They are not (fortunately) one reply questions, but, rather, stimulating discussion topics for numerous members. We have several very able mathematicians and a reliable way to quantify sharpness measurements (BESS readings).
I have long felt that current technique for flattening and polishing chisel backs was not the Tormek's strongest area. Nor have I felt that most users fully master the leather honing wheel. I look forward to advancements in these areas.
Ken
Stig,
Your "really nerdy info" comment gave me a good belly laugh! I agree, however, I also recognize the value of really nerdy stuff.
I installed and repaired high speed data circuits. Factors which were not critical for dial up circuits could easily put a high speed fiber optic circuit out of service. Most people would consider the precision of atomic clocks overkill. If a parent is watching the clock to make sure the child gets on the school bus, atomic clocks are overkill. If the same parent deposits money at a bank, that deposit must go through fiber optic data circuits to the Federal Reserve. Those nerdy atomic clocks make this possible.
In the same way, really nerdy info can infiltrate into daily sharpening. The kenjig is essentially just a rectangular small piece of plywood. However, this simple appearance masks some high power nerdy trig, added by Dutchman's work. I do not know where this nerdy discussion will lead. I do believe that it will benefit the average user, just as the average family car owner has benefitted from the developments in auto racing.
Welcome nerds!
Ken
So, if I'm reading Stickan's post correctly, the difference was done intentionally, to create a microbevel, and/or insure the edge is being hit during honing? (Just making sure I'm understanding it correctly). If so, that could easily be addressed in the documentation. (I agree with the concept... fwiw).
Also I noted two things on wootz post of the honing testing... he stated it doesn't apply to honing on the LA-220, and I guess we'll have to wait for the report to see if it could even be extrapolated to it. But, (and call me skeptical)... that, based on Bessex chart, an edge can go from "razor blade" sharp to an edge defined as "moderately rolled"... "edge in need of maintenance or repair" based on a .2 deg. angle change in honing? I'm not saying I doubt that's what the test may have shown... but for me, that raises many more questions.
Well, It's not a microbevel. Its a polished edge.
Now, with this said, using much pressure over a long time can change the angle slightly. But I doubt that this is the reason for the result using the Bess system.
I will be in England during the weekend at the European Woodworking show and will have limited time in front of the computer.
I will try to get time to answer questions once a day if I see that I need to "jump" in to the discussion.
Sincerely,
Stig
It is really encouraging to know that Tormek engineers' recommended honing angle for chisels of + 0.4-.5 degrees is in line with what we named the Best Honing Angle in our study for knives.
This study was accomplished for paper wheels at high RPM with 0.5 micron diamonds, which is pretty an aggressive honing compound, taking them closer to hard hones than the leather wheel - this explains quick worsening of the BESS score with further angle increase.
After it is published in the Sharpeners' Report, I will ask the editor's permission to publish here - if not allowed will send complimentary copies to Jan, Dutchman and who else asks, it is a digital magazine.
What I can't agree with, is the "nerd" label - calls not to overscience sharpening can only halt progress.
Quote from: Stickan on September 14, 2017, 02:04:56 PM
... Of coarse there is a difference with a knife and a chisel.
It would be very interesting to know how the knifes are honed. Is the result the same when using the knife jig or honing freehand?
Best,
Stig
I probably would have never stumbled over the 215/220 issue if honed knives freehand.
The problem revealed only because we use a frontal vertical base we designed for honing and computer software allowing to set honing angle with high precision, as described on our website
http://knifegrinders.com.au/11Shop_VB.htm (http://knifegrinders.com.au/11Shop_VB.htm)
http://knifegrinders.com.au/05Equipment_scripts.htm (http://knifegrinders.com.au/05Equipment_scripts.htm)
Though we normally hone on paper wheels, there are certain steels better worked on leather wheels, we have a set of them with honing compound of different grits.
And because we sharpen collector's blades to submicron level, < 70 BESS, a 1 degree discrepancy at the very edge apex is brutal, even 0.5 degree is with leather, and 0.2 with paper wheels.
Wootz,
I'd love a copy !
Kind regards,
Rich
Wootz,
"What I can't agree with, is the "nerd" label - calls not to overscience sharpening can only halt progress."
I am sorry if you felt that I wrote this in a negative way. Its actually the opposite. When it comes to knifes I call myself and friends the same but with a positive tone.
The forum is a community with high understanding of Tormek and sharpening. English is not my born language and maybe nerd can only be used negatively? its time for a change if so.
Or come with an suggestion what we forum members can be called when we are going deeper in to details :)
Sincerely,
Stig
Quote from: Stickan on September 15, 2017, 06:37:13 AM
Or come with an suggestion what we forum members can be called when we are going deeper in to details :)
OCD? ;) :D
Stig,
I did not take it negatively. Rather; I thought it was funnily true.
Kind regards,
Rich
We all share a common passion for achieving sharp edges with the Tormek. I recall reading somewhere that early man used tools before he discovered fire. I would call that an ancient craft.
In the common pursuit of this passion, we are bound to have minor misunderstandings from time to time. Let us march on and let this unintended midunderstanding pass. Personally, I prefer to be in the company of dedicated, passionate friends to being part of a group of less interested members.
Ken
I think i owe an apology to Stig - it was a knee-jerk reaction of mine just because earlier that day someone said I overscience sharpening :o
Quote from: wootz on September 16, 2017, 01:54:31 AM
...because earlier that day someone said I overscience sharpening :o
Compliment... as far as I'm concerned.
I've learned tons from what you're doing, so.... keep 'oversciencing'!!! ;)
Quote from: wootz on September 16, 2017, 01:54:31 AM
I think i owe an apology to Stig - it was a knee-jerk reaction of mine just because earlier that day someone said I overscience sharpening :o
They say that until they need your help or something that you have learned.
That tends to be a failure on their part that science really only provides theories that are the best we know at the time, until something can be actually proven. (like the Apollo Astronauts on the moon, with a feather and a hammer)
Quote from: Stickan on September 15, 2017, 06:37:13 AM
Wootz,
"What I can't agree with, is the "nerd" label - calls not to overscience sharpening can only halt progress."
I am sorry if you felt that I wrote this in a negative way. Its actually the opposite. When it comes to knifes I call myself and friends the same but with a positive tone.
The forum is a community with high understanding of Tormek and sharpening. English is not my born language and maybe nerd can only be used negatively? its time for a change if so.
Or come with an suggestion what we forum members can be called when we are going deeper in to details :)
Sincerely,
Stig
I am just off to measure my honing wheel but stopped to check the definitions of "nerd" and "geek" in my new Concise Oxford Dictionary; I commend the latter term so far as UK English is concerned - "a knowledgeable and obsessive enthusiast".