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Hello,

[TL/DR: Use a calculator and calipers if you want the most precise way of setting an angle]

The intrinsic flaw in using the AngleMaster for knives is described at length in posts such as this one or this other one. The design of the WM-200 offsets the measurement by exactly half the total taper angle of the blade. This is a systematic error that cannot be reduced by training, not by increasing measurement precision of wheel diameter, etc.

The KS-123 is based on a design that allows to measure directly the angle between the tangent to the stone at the point where the apex will sit and the axis of the sharpening jig (which coincides reasonably well with the plane of symmetry of the blade when using the KJ). So no such skew here.

Precision is a different matter. It can come from many things, from the size of the needle on the KS-123 to whether or not you put a light in just the right place when you use the AngleMaster, but also what tolerances cumulate in the construction of the devices, how reproducible the manufacturing process is, etc. etc. To have a substantiated answer to "how precise is the KS-123 ?", you'd need to get a statistically significant sample of jigs, and not only a goniometer but also a consistent way of setting up the tool before you take your measurement. Not sure it's going to happen.

My gut feeling is that the KS-123 has a precision of around 1dps when setting an angle, and probably a fraction of that when reproducing an angle that has been ground using the KS-123 in the first place if your setup process is consistent. In my opinion, the biggest source of error in using the KS-123 comes from the hysteresis/backlash due to the friction between the black plastic part and the metal body and the flexibility oof the plastic needle. It can be reduced with a tad of silicon grease, and consistency can be improved by always approaching the target angle from below by raising the support bar.

Using a calculator rids you of many of these imprecisions. Calipers can be adjusted precisely with very little hysteresis, and the values you use are large enough that a little error will only have a small impact on the result. Much smaller than if you sum the width of the needle with the typical hysteresis of the KS-123.

After you use the angle setter you mat want to try coloring the knife edge with marker and rotate wheel ny hand to see what is removed. This is a double check on the setting.

I ALWAYS do this, no matter how I set the angle.  On EVERY blade.  On EVERY wheel diameter change (and even between Tormek diamond wheel changes where the diameter doesn't change). 

Yes, that. It is a tremendous help when it comes to gauging what the motion has to be to sharpen the tip (and heel) properly.

I haven't tried yet, but maybe it's possible to setup the MFB in such a way that you could somehow use the truing tool on the side, at least between the outer edge and a minimum radius ?

I have done so for a time, but found it inferior to using a fine ceramics rod with an angle guide. This gives me the longest time between actual grinding sessions.

John, from everything we've seen on this forum, Tormek support is top notch. They may be a bit understaffed at times, but they're always professional and careful about their reputation as a premium supplier. You're not taking any real risks here. And this way you'll keep your (long) warranty.

I don't have a lot of experience with my rock hard felt wheel. However, having sharpened maybe 20 knives on it, I find I have good results (ie 20 BESS higher) results with hard steels (63+ HRC). With standard steels, I'm actually worsening my BESS scores.

I probably don't use it right, but now I'm more after edge retention than initial sharpness.

If it is just a scratch, I would not really bother doing anything other than using it properly, edge trailing. A small bump won't be an issue, and will get smoothed out overtime.

If there is a bit of leather that has been cut and stays raised, i'd carefully trim that off, removing as little as possible so whatever is left of the scratch gets pressed down when honing, rather than lifted and folded backwards.

Also Wootz was dedicating a lot of effort to getting the lowest BESS scores, which is an indication of how thin the apex of the edge is. But this result can be altered by sheer oxidation, not to mention a few cuts of hard vegetables on a wooden board. In his book, there is a chapter about edge retention which is not really dependent on initial sharpness but rather on apex angle.

That being said, I concur with John in making an intermediate check before honing to get a good look at the edge. The burr should be visible, but its root should be clean. If nicks appear when honing with only leather wheel and PA-70, I'm clueless. And I wouldn't use a rock hard wheel before I get satisfactory results with the leather wheel. That would eliminate a possible culprit in addition to providing a sound comparison basis.

@mrducks, do you sharpen edge leading or edge trailing ? Do you use a lot of pressure when honing ?

Hello Steve,

This overgrind in the middle is common with a lot of knife sharpening setups where you can easily spend more time sharpening the middle section than the heel and tip. It is especially pronounced on the Tormek which removes metal fast (the downside of fast sharpening). You will have to learn to focus on spending more time/pressure in those area that see the stone less often.

Do you sharpen going back and forth, or only from heel to tip ?

Also, rounding out the shoulders of the stone helps a lot.

Lastly, it is important to care about the way you lay down your knife: make sure it is not tilted towards the tip when you approach the stone. For safety's sake, I prefer to tilt it ever so slightly towards the heel.

Cheers,

Nick.

I own the KS-123, and end up more often than not using a software-based solution, even when sharpening a single or few knives at a time.

There is some friction in the KS-123 that, coupled with the flexibility of the plastic needle indicating the sharpening angle, makes for a 1 dps-ish precision. And despite the fact that Tormek wrote in their KS-123 patent that "There may be errors in computation-based solutions", I find the calculator-based process to be much more repeatable, resulting in a burr being raised in just a couple of strokes on the ungraded SG. This also minimizes the amount of metal removed, increasing the lifetime of knives (or at least the time before requiring thinning).

Also, once you get the hang of it - and , granted, with a bit of hardware for quick projection distance measuring/setting - I'm not sure the KS-123 setup is a lot faster.

All in all, I think the KS-123 has the advantage of being a reasonably accurate, self-contained solution, but calculators and calipers (and an adjustable projection distance) make for a more efficient process overall.

So this is actually a thing, even though not a Tormek thing...

Still, there are two fundamental issues with such wheels :
- If the wheel is noticeably wider than the serrations of the knife (as seems to be the case in the pictures on their website), then the result will be rounded out teeth and untouched "valleys". If the wheel is noticeably narrower than the serrations, it will be fragile *and* will cut aggressively.
- How do you restore them when they wear down ? I guess one could use diamond plates and aim for a triangular shape, but it will be fidgety.

IMO, a thin triangular or cylindrical rod used either freehand or on an edgepro-like system will make for a much more controlled process and repeatable results. Along with a flat benchstone for the backside.

This setup is always square to the usb and the grinding stone. This rig gives me one less potential outof square variable.

Yes, but it might also be a good way of making it out of round by worsening high/low spots. If you make your support long enough that you can rest the far end on a second USB, you also eliminate that risk.

Wow, a triangular wheel ? With a dual-MB102 "spaceship" contraption for truing it ? Or with a diamond-coated apex ?

Hello @Mojoman,

First of all, the nicks in the stone have nothing to do with how you set the angle. The WM-200 is a dodgy solution for setting knife angles, and if you want to "just polish", then a sharpie is a much more efficient tool, but that's beyond the point.

I think your issues come from a few things :
- You may not be holding the knife jig against the USB firmly enough. So whenever the knife starts moving a bit with the rotation of the stone, you enter the domain of static friction between the blade and stone. Then things go quickly amiss from here : the knife will move up quickly, the angle will increase quickly, and then whenever the knife is stopped again; either by your hand or by the USB or whatever, it will dig into the stone at a high angle. Had you been using the SG stone, you'd just have ruined a tiny portion of the knife edge, but not the stone. With the SJ, the stone yields first. The remedy to this is to build more experience with the SG before using the SJ stone heavily. You mentioned needing only to sharpen a little on the SJ and then strop, have you tried sharpening a little on the SG then stropping, to see if the edge is satisfactory ? Or even just honing on the leather wheel ?
- Polishing edge trailing (with the stone rotating away from the edge) avoids this issue, but creates others : a foil-like burr, slower grinding, MB-102 or FVB mandatory for controlled-angle grinding,...
- Sharp shoulders on the stone, as mentioned by Ken. However those will tend to create nicks on the shoulders themselves when laying down the knife. Rounding them out is good practice for all stones, and especially on the soft SJ to avoid chipping it when truing it.

I have a rather complex history with the SJ stone : I have been using it a lot at first, as I ordered it along with my T8, probably because I was used to sharpening with high-grit japanese benchstones. And I've been nicking it quite a bit then. Then as I got rid of the rookie mistakes such as not holding the jig properly, I also got rid of the nicks. But careful experiment showed that the assertion by Tormek that the SJ eliminated the need for honing was incorrect : the burr may not be apparent, but a tiny bit of plastified metal sits at the Apex, and it needs to be removed with about as much honing as a SG-generated burr. Also, honing with the PA-70 compound after a few light passes on the SG leaves such a good finish that I haven't felt the need for SJ-based polishing on most knives. So now I use it only occasionally, on very specific high-hardness knives where looks are somehow more important than actual edge retention in the kitchen.

And you may want to take a good look at the MB-102. It is one of those Tormek pieces of hardware that I feel should be part of a knife-sharpening kit, or a T4/8 knife sharpening edition, as they greatly increase sharpening efficiency. If you often reset angles, the KS-123 is a good tool as well.

Cheers !

Hello,

While I don't sharpen enough knives to see this phenomenon with the SB, it is my experience that this kind of issue is inherent to the Tormek principle, said otherwise it is a self-amplified phenomenon.

Sure, you don't intentionally "press harder every revolution in the same place", but think of what happens when a low spot exists for whatever reason : if you are sharpening edge leading, each time your blade will pass this low spot, it will lift ever so slightly at the incoming lip of the low spot, then dig in a bit shortly after. The result is a low spot that gets deeper with each rotation. This kind of oscillatory behavior is of course not limited to Tormek, but it is rooted in a locally favorable combination of resonant frequencies, characteristic times  (those of the tools or the operator), and gains (pressure).

I noticed this phenomenon to be especially obvious when I first toyed around with Wootz' grading technique using diamond plates. It seems I was using the perfect amount of downward pressure for the phenomenon to get noticeable quite quickly. Using less pressure helped, as did using another usb to support the far end of the diamond plate.

I don't think there is anything wrong with your SB's, I would try truing earlier (if you have to true 2-4 mm it is way too late), see if edge trailing gives satisfactory results, and also try using less pressure (I know the SB's glazed feeling makes you want to press real hard). Maybe deglaze often using a diamong plate with little pressure.

Hope this helps.