Start Tormek and end with Tormek. You can't use any compound(paste, spray....) other than PA-70, and can't use paper wheels. What is the lowest BESS score you can get in this case?
I can get 100 ~ 150 with the Victorinox kitchen knife.(15 degrees per side)
Anything around 100 is very good.
I get with SG + SJ = 70 BESS.
You get under 100 BESS when you center the knife in the jig, and maintain the same angle as the knife goes from one wheel to another, and finally to the leather wheel.
Quote from: wootz on February 04, 2018, 11:31:05 AM
SG + SJ = 70 BESS
In my case,
SG + SJ = over 180 BESS
SG + SJ + Leather wheel(PA-70) = 100~150 BESS
70 BESS? Wow!
I use SJ as you told me before, but I can't get such a good score. :'(
Having set the edge on SG, but before you go to the SJ, run the blade on a very finely graded SG just once each side; continue on SJ at a shallower angle
I gave a sharpened knife to a girl named Bess, she scored it a '10'. 8)
(Sorry, couldn't resist).Quote from: wootz on February 04, 2018, 11:39:08 AM
Having set the edge on SG, but before you go to the SJ, run the blade on a very finely graded SG just once each side; continue on SJ at a shallower angle
I still would try a 3-4 deg. higher angle very light pass... if lower doesn't work for you. :) I do like the one pass each side on the SG prior... but would add, very light pressure.
Quote from: cbwx34 on February 04, 2018, 03:15:15 PM
... but would add, very light pressure.
Shouldn't the pressure on the blade at all times be just enough to maintain firm contact with the wheel, no more?
If grinding goes too slow, change to a coarser grit, but do not press harder because by pressing hard you bend the edge apex, and will never get your edge even shaving sharp, let alone true razor sharp.
To illustrate that, I like the SEM image of a burr formed by a one-sided grinding - your Bess girl would score it
-1?(https://scienceofsharp.files.wordpress.com/2015/01/burr_08.jpg)
https://scienceofsharp.files.wordpress.com/2015/01/burr_08.jpg
@SHARPCO:
Try sharpening at 10 dps - a more acute angle provides for less hits on the edge apex and more room for mistakes from inconsistent grinding angle.
After you gain confidence in getting 70-90 BESS edges, move to sharpening at 15 dps - if you see worsening in the results, sharpen at a shallower angle.
Of all, 20 dps requires the most accurate setup to maintain consistent angle between the wheels.
In theory, in principle, the edge sharpness is not directly related to the edge angle, and you can get the same sharp edge on a 40 degree included knife edge as that on a 15 degree razor, but practically is easier achieved on an acute-angled edge.
Quote from: wootz on February 04, 2018, 11:40:25 PM
Quote from: cbwx34 on February 04, 2018, 03:15:15 PM
... but would add, very light pressure.
Shouldn't the pressure on the blade at all times be just enough to maintain firm contact with the wheel, no more?
If grinding goes too slow, change to a coarser grit, but do not press harder because by pressing hard you bend the edge apex, and will never get your edge even shaving sharp, let alone true razor sharp.
Good question actually... haven't really defined "light".
You're right pressure should never be hard, and you don't press harder to go faster. "Let the stone do the work" is the common saying.
But for the final light passes... I try and go as light as possible... to the point where the blade is just barely touching. It's probably more of a sound that I hear the stone touching vs. even feeling it with pressure, if that makes any sense. Particularly on higher angle passes... I'm trying to just contact and remove burr and refine the edge... not creating a microbevel, if that makes sense. (So, slightly more pressure if you want to actually create a microbevel). That's the goal I'm striving for. (Realistically, may not be humanly possible, but it's the goal).
Quote from: wootz on February 04, 2018, 11:40:25 PM
In theory, in principle, the edge sharpness is not directly related to the edge angle, and you can get the same sharp edge on a 40 degree included knife edge as that on a 15 degree razor, but practically is easier achieved on an acute-angled edge.
Oh boy..... :o (You specifically talking BESS here?) ???
"...(You specifically talking BESS here?)"
Why? - Not.
About sharpening in general. Practically it is easier to get a razor sharp edge on an acute-angled edge, but nothing prevents you from getting it on any edge, in theory even obtuse - nothing but your grinding setup accuracy.
The edge apex radius, and the cutting edge angle are unrelated.
It's similar to your observation that you get a sharper edge if you sharpen the same knife twice.
For the 2nd time you sharpen an edge that has been straightened by the previous sharpening, hence less apex disturbing miss and hits.
Quote from: wootz on February 05, 2018, 03:22:58 AM
"...(You specifically talking BESS here?)"
Why? - Not.
About sharpening in general. Practically it is easier to get a razor sharp edge on an acute-angled edge, but nothing prevents you from getting it on any edge, in theory even obtuse - nothing but your grinding setup accuracy.
The edge apex radius, and the cutting edge angle are unrelated.
It's similar to your observation that you get a sharper edge if you sharpen the same knife twice.
For the 2nd time you sharpen an edge that has been straightened by the previous sharpening, hence less apex disturbing miss and hits.
So, you can sharpen an edge at 45° per side, and obtain the same sharpness? 50°? 60°?...
I'm not sure what you're referencing... when saying "you get a sharper edge if you sharpen the same knife twice", although I have talked about "2nd sharpenings" being better... I guess I'd have to see the context... I'm not seeing the similiarity.
Quote from: wootz on February 04, 2018, 11:39:08 AM
Having set the edge on SG, but before you go to the SJ, run the blade on a very finely graded SG just once each side; continue on SJ at a shallower angle
I can't spend time grading stones, so I need to use a second SG for #1000. That is acceptable. However, when I use Stone grader, there is always a problem that the middle of the stone becomes rougher than the outside. It seems that more pressure is applied to the outside than the middle. In addition, this leads to some loss of stone flatness.
Do you use a Stone grader for SG # 1000?
Quote from: SHARPCO on February 05, 2018, 09:42:31 AM
Quote from: wootz on February 04, 2018, 11:39:08 AM
Having set the edge on SG, but before you go to the SJ, run the blade on a very finely graded SG just once each side; continue on SJ at a shallower angle
I can't spend time grading stones, so I need to use a second SG for #1000. That is acceptable. However, when I use Stone grader, there is always a problem that the middle of the stone becomes rougher than the outside. It seems that more pressure is applied to the outside than the middle. In addition, this leads to some loss of stone flatness.
Do you use a Stone grader for SG # 1000?
Sharpco, your post makes me wonder if the SJ wheel is even the right choice for your setup? If you're to the point where swapping stones (which brings even more issues into the process) is a better choice than taking the time to grade a stone... I'm thinking the SJ wheel might actually be "the weakest link". It's a decent stone, and does a good job of polishing, but at the expense of not being particularly fast at the job. (You may have heard the saying, "good/fast/cheap"... pick two).
I'm wondering if a compound on the leather wheel that doesn't break down as fast as the Tormek compound, might be a better alternative? It would increase the speed of the leather wheel's performance, and not breaking down would keep it more consistent. You might have to experiment with finding the balance between "sharp and polish" (maybe someone with more experience can help here). Or, maybe look at an entirely different finishing step (Steve Bottorff's setup comes to mind).
Just a suggestion... sometimes I find myself trying to "make something fit", when it may be better just to take a different approach.
Tormek has never been said to be quick, it is designed for quality, not quantity.
There are 2 major groups of sharpening machines - "professional" and "commercial", and though these terms overlap, when they say "commercial" they mean volume sharpening at a speed ~1 min per knife.
Examples of "commercial" machines designed for volume sharpening are those made by Catra, F.Dick, TruHone and Cozzini (PrimEdge).
In this sense, Tormek is "professional" and has never manufactured machines for volume sharpening; the best speed you can get on Tormek is 5 min per knife.
It still can be used for speedy sharpening by breaking the classic Tormek 3-step sharpening protocol, and going from the coarse SG or SB wheel straight to honing, and many professional sharpeners go this way, just the edge you get will be within 150-200 BESS.
Interesting posts. I have often thought we should mention both the volume and the quality expectations of the work. I believe we run the full gamut on this forum, which I believe is healthy.
I am on the low end of the volume totem pole. The only knives I sharpen are my own. I have added a few for forum work over the years. I probably have twenty now. I rarely sharpen more than four or five at a time. I have no time constraints. I have never charged for sharpening, although I do my best to maintain quality workmanship.
Some of our members, (including you, Sharpco?) have developed high volume sharpening businesses. The farmers market guys may only work Saturday mornings, however, those mornings involve high volume sharpening. On the quality side, we have numerous businesses which specialize in good work at a reasonable price. We also have businesses like KnifeGrinders, which specializes in very high quality sharpening no doubt for comensurate prices. There is room in the market for both.
I have pondered using two SG wheels, one graded coarse, the other fine. I think going this path really requires having at least two Tormeks, three if you are also routinely using the SJ. For high volume work, I think that having at least one assistant is useful.
I would consider some other options. I don't know if it would make any practical difference, however, the SG-200 wheel has a 40mm width instead of the 50mm of the SG-250. The DWF-200 diamond wheel has a grit of 600. It is diamond. The wheel should never wear or get out of true. As a trained sharpener, I would suggest you use it in a T4 or T8. It will work in the T8 as well as any wheel worn to 200mm, and will not wear beyond that point.
Grepper made some very revealing microscope photos comparing regular grinding pressure with making the last few passes with very light pressure. I suggest you experiment with this instead of regrading your grinding wheel.
I have used valve grinding compound with the leather honing wheel. It cut more aggressively than PA-70. It might provide the middle step you desire and eliminate using the stone grader, perhaps in conjunction with light pressure. It does not polish as highly as PA -70. It is also inexpensive and readily available..
With my 80 grit CBN tests, I noticed a hundred point improvement in BESS by using the wheel grinding away from the wheel. (400 instead of 500) It slowed grinding slightly, but was faster than regrading the stone.
One way to speed up the stone grading process is to have several knife jigs. Grind half a dozen knives with a coRser stone before grading. Loading different jigs uniformly is easy with a kenjig or Wootz' applet.
Ken
ps to Wootz: I finally googled "Wootz". Very interesting choice of username!
Finally got around to an attempt at part of the question... SG + SJ = ?? BESS. I don't have a BESS, so using wootz's Sharpness Chart (https://forum.tormek.com/index.php?topic=3447.0) tests... here's some of what this blade will do...
- Shave hair w/o touching the skin, and every shave test above this (of course)... (Some "treetopping", but not many, so won't count)
- Slices newsprint/receipts/phonebook paper either direction and will pushcut w/grain (and against grain if done carefully)
- Fillet receipt paper (lower score than filleting printer paper?)
- Don't have cigarette paper, so used the "old standard"... clean slice of double and single ply TP in either direction (figured I'd show a pic of the "lowest" test)...
(https://forum.tormek.com/index.php?action=dlattach;topic=3518.0;attach=1843)
So BESS = 80-100 maybe? (More? Less?) Hopefully at least in the chart's "Crazy Sharp" range? ;)
The knife is a Dividend in M390 steel. / 15° per side / same angle on both wheels / finished with 2-3 light alternating passes still at the same angle on the SJ wheel... nothing "special" done to try and improve sharpness (no other stropping, etc.). (All sharpening/honing "edge leading").
(BTW, not bragging (I have no idea if its even comparatively good or not)... just trying to establish what's possible off the SJ wheel with a regular sharpening).
Quote from: cbwx34 on February 13, 2018, 01:25:26 AM
Finally got around to an attempt at part of the question... SG + SJ = ?? BESS. I don't have a BESS, so using wootz's Sharpness Chart (https://forum.tormek.com/index.php?topic=3447.0) tests... here's some of what this blade will do...
- Shave hair w/o touching the skin, and every shave test above this (of course)... (Some "treetopping", but not many, so won't count)
- Slices newsprint/receipts/phonebook paper either direction and will pushcut w/grain (and against grain if done carefully)
- Fillet receipt paper (lower score than filleting printer paper?)
- Don't have cigarette paper, so used the "old standard"... clean slice of double and single ply TP in either direction (figured I'd show a pic of the "lowest" test)...
(https://forum.tormek.com/index.php?action=dlattach;topic=3518.0;attach=1843)
So BESS = 80-100 maybe? (More? Less?) Hopefully at least in the chart's "Crazy Sharp" range? ;)
The knife is a Dividend in M390 steel. / 15° per side / same angle on both wheels / finished with 2-3 light alternating passes still at the same angle on the SJ wheel... nothing "special" done to try and improve sharpness (no other stropping, etc.). (All sharpening/honing "edge leading").
(BTW, not bragging (I have no idea if its even comparatively good or not)... just trying to establish what's possible off the SJ wheel with a regular sharpening).
Did you sharpen in the following order?
SG(#220) -> SG(#1000) -> SJ?
Quote from: SHARPCO on February 13, 2018, 11:44:49 AM
Did you sharpen in the following order?
SG(#220) -> SG(#1000) -> SJ?
SG(#1000) -> SJ
The knife had been previously reprofiled... this sharpening was a few alternating passes on the SG wheel at 1K... then to the SJ wheel... around a dozen or so passes per side, with the last 2-3 light alternating passes.
By what you describe, you've got an edge at <= 80 BESS.
It is not in the Sharpness Chart, but if it can split a chest hair, but cannot a head hair yet, it is 70-80 BESS, you may try this test as well.
I have several M390 knives in my collection, and the SJ won't work on them but one.
I tried edge-leading and edge-trailing, at the exact edge angle, at +0.4-0.5 degree and at a less to no avail, except that one blade that yielded the best of 80 BESS on one occasion.
The blades they get of the M390 steel depend on the heat treatment quality, and I would say the heat treatment hasn't been done to its best if M390 responds to SJ at all.
It is not supposed to.
Quote from: wootz on February 13, 2018, 04:07:21 PM
By what you describe, you've got an edge at <= 80 BESS.
It is not in the Sharpness Chart, but if it can split a chest hair, but cannot a head hair yet, it is 70-80 BESS, you may try this test as well.
I have several M390 knives in my collection, and the SJ won't work on them but one.
I tried edge-leading and edge-trailing, at the exact edge angle, at +0.4-0.5 degree and at a less to no avail, except that one blade that yielded the best of 80 BESS on one occasion.
The blades they get of the M390 steel depend on the heat treatment quality, and I would say the heat treatment hasn't been done to its best if M390 responds to SJ at all.
It is not supposed to.
Red hair or green hair? ;)
(Inside joke)I'm not much on the "hair tests"... I think a lot of it is technique. But it will whittle a chest hair, and to my surprise even a head hair in some spots on the blade.
I'm a bit dubious when I read "this stone won't work on this steel". Most will have some effect. If you take one of your M390 knives that it
doesn't work on... you see absolutely no difference? Polish only one side, and see if it looks different than the other. Raise the angle 3-4°, and make a few passes on one side... any evidence of a microbevel? Is there 'black' showing up on a cleaned SJ wheel? If yes to any of these... it's doing something....
As for this knife, all I can say is the bevel was definitely polished by the SJ wheel, although not a perfect mirror... I can still see scratches from the SG wheel... but more mirror than hazy (if that makes sense). (Why am I typing)...
(https://forum.tormek.com/index.php?action=dlattach;topic=3518.0;attach=1845)
Anyway, it's holding up well cutting some cardboard. But I don't have any other M390 to compare to at the moment. It is a Kershaw and at the lower end $$ wise from what I'm seeing on the net... so being more a "mass production" knife... wouldn't surprise me if the heat treat isn't optimal.
Thanks!