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That's a very interesting subject, thanks !

It incidentally explains also why many of the MagnaCut knives were sold out everywhere (and why there weren't many). Hopefully we will be able to see (and sharpen) MagnaMax chef knives.

Thanks for sharing these results !

I read the report, which is very informative and detailed.

A few comments/questions, if I may :

First, there are many differences between the compared methods. The way I was taught, you have to make sure only one parameter varies when you want to make a comparison between two methods, and you have to have statistically significant samples. If I understood properly, you could very well have chosen the following titles for your report :
"Controlled Angle yields superior CER compared to Freehand" (which we have to say kinda makes sense) or if we wanna get cheeky :
"Round sharpening and honing medium yield superior CER compared to flat ones" or even :
"Eric Ho gets better CER than other sharpeners"  .
The huge difference in methods may only allow to increase confidence that "better sharpeners get better BESS *and* ICP", rather than infer a second-order polynomial relationship between BESS and ICP. There are mainly four clusters, you have a high chance of being able to fit those rather well with a second degree polynomial. It would also be true if you plotted BESS score vs age of sharpener.
[EDIT]Wootz and L. Thomas seem to agree on an empirical formula that ties edge retention to hardness/composition of the steel and edge angle only, which would imply ER only depends on BESS scores to the extent that higher wear-resistance steels allow for better initial sharpness. Also, a basic razor blade has very low BESS, but low wear resistance and poor edge retention.[/EDIT]

More seriously, if we look at the graph on page 20, but only take your results into account... Why can't we conclude "better BESS scores yield worse ICP overall" ?  That would be consistent with what several sharpeners have reported, when polishing the edge. I tried to guess the ICP/BESS values from your graph to put it inside an Excel spreadsheet and look at the global tendency, as shown on the attached image. That can only be proven true or false (or unrelated) by having a bigger sample and controlled variation of experimental parameters.
I understand it is a very complex thing to do, but changing so many things between two subsets makes it hard to draw any conclusion.

More on the "controlled angle" part. Wootz and Larrin Thomas concluded that angle was by far the most important factor in edge retention. So it would seem natural that methods that yield lower edge angle spread also yield better CER. That would also seem consistent with the fact that Wootz himself seemed to hint that others methods work well, without the whole paper wheel buffing shebang. But what about the Tormek protocol : grind using SG, hone using leather ? What BESS for what CER, when done by Eric Ho ?

A word on the Ken Onion WorkSharp : I own it as well as the T8, and am by no means a professional sharpener. I set it up with a FVB so I can better control the angle. While I consistently get 100-110 BESS @15dps using a simple protocol on the T8, I usually get 120-140 BESS with the WorkSharp with the fine belt followed by honing on a leather belt with Tormek compound. So a professional sharpener being satisfied with 250 BESS leaves me... flabbergasted. Side note : I only use it on lowest speed unless I need to grind a bolster.

Hope this helps with this edge retention topic, which I believe is indeed key to knives sharpening.

Nick.

Rich, this is a very nice and useful piece of work. Thanks a lot for sharing !

I was wondering, are you familiar with heat set inserts ? They are inexpensive and make for a very easy way to add strong threads to 3D-printed parts. All you have to do is :
- change the diameter of the hole to the appropriate one for the thread size (3.8 mm for a M3 insert for instance, and some even go as far as making a conical insert to minimize bulgin around the insertion point)
- put these holes inside a cylinder-shaped modifier so that the wall thickness around the insert is about 80% of the thread size (3.2mm at least for M4 for instance),
- add them using a soldering iron (any will do but using the included toolheads will make it even easier).

A nice trick is to put them on the backside if you can so that the screw tends to pull the insert into the 3D printed part instead of ripping it out. You can add the modifiers as separate bodies in F3D so they will be appropriately placed in your slicer. I can make the modification for you in your design if you wish.

Many thanks,

Nick.

@kwakster, the quality of your work is amazing. Thanks for sharing those with us. I love the new look of the handle.

If sub 200 Bess is your goal then sell out and do all your sharpening on belt grinders and go for volume rather than quality.

I found that controlled angle grinding on a belt grinder followed by controlled honing on leather belt+PA70 compound yield 120ish BESS results. I don't think speed and quality are exclusive, and when reprofiling in involved, this is clearly the way to go. The Tormek has an edge in dust generation and "zen" power, plus it shines when it is not exclusively used for sharpening knives.

Just as those who sharpen  knives exclusively occasionally complain about having  to pay for including the SE-77 with the T8, woodworkers might complain about paying to include a US-430.

I was not suggesting including an **additional** US-430 that would sit in a drawer for those working only wood, but rather including it as standard delivery.
As far as I know, it is not a hindrance for those who wouldn't use the additional length. Regarding manufacturing costs, I doubt an additional welding and a few grams of steel would make much of a difference (plus the US-430 only uses straight bars).

Thanks for the link. Unfortunately, it looks like they're out of stock too...

Stig is the master of pressure control, from heavy pressure for heavier grinding to finishing with very light strokes.

I thought I remembered an advanced sharpening video where Wolfgang explains that heavy pressure does not lead to faster grinding because it kinds of glazes the SG. Or am I mistaken ?

I am curious though as to what configuration leads to bumping the jig collar into the support legs. It would mean that the top of USB is at or below top-of-wheel level, right ? If that's the case, the angle has to be small indeed...

As for the US-430 not being part of the standard T8 delivery, I think that's a bit cheap.

I'm not an abrasive specialist, but in my experience, the "grading" of the stone lasts about an order of magnitude of around 20-40 strokes. Longer knives (obviously) or higher pressure will be in the 15-20 strokes range. And the way it goes back to its "in-between" state is not linear : very coarse or very fine grit lasts only for a couple strokes.

So it does not go from coarse to fine but from coarse back to standard and fine back to standard. It gets coarser by removing Al2O3 particles and exposing fewer, fresher ones with sharp edges. It gets finer by creating a fine slurry that fills in the gaps and makes the stone smoother.

In any case you have a substrate of Al203 particles of a given average size and even if you applied a very fine diamond stone you would still feel the effect of the substrate. Plus the finer the particles, the quicker they'll wash away.

TL/DR : the particle size in the SG gives its standard performance, you can make it vary temporarily by creating ridges or filling in the gaps. The farther you go from its standard state, the shorter the new state lasts.

Hello WimSpi,

I don't use my diamonds wheels for knives much, but after a bit of experimenting with grading the SG or not, using the SJ or not, I settled with the following simple process for everything but very high end kitchen knives  :

Sharpen @15dps on ungraded SG, hone thoroughly @15.5dps on leather wheel with PA-70 compound starting on the same side as the last stroke on SG.

If you have diamond wheels and a 250mm leather honing wheel I'd suggest : Sharpen @15dps edge leading on DF wheel, then hone edge trailing on leather with PA-70, using MB-102 or FVB, increasing the USB height by a half turn of the MicroAdjust nut. This should be a rather quick workflow, maybe not with the smoothest-looking edge, but with pretty decent cutting performance and edge retention.

Wouldn't the interference problem be solved by separating the blades ?

Martha, welcome to the forum. Your knife exhibits a common issue with Western knives: they often have what is sometimes called a "full bolster".

It is a safety feature intended to prevent the user from nicking their fingers with the heel of the blade. In Japan, where cooks are usually more educated with knife handling, there are usually none. The issue with full bolsters is precisely what you are encountering : it's a PITA when it comes to sharpening, and the gap that gets created hinders cutting.

There are several threads about this, such as this one.

TL/DR : You can reduce the bolster using your Tormek, but it will be time-consuming and will cause increased and uneven wear to your wheel. A belt grinder (preferred) or a bench grinder will make it faster.

Cheers,

Nick.

While my first advice would be to contact tormek support, if they haven't answered I'd simply return it and order another one.

All the T8 I know have a low humming sound, not this. It sounds like there is some lose debris somewhere in a bearing or whatnot.

It looks nice, I'd love to try one. Unfortunately, most seem out of stock at the moment, as if this steel wasn't available for this kind of knife anymore...