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Many thanks for the follow up Nick.

I currently record images of customer knives, before & after, as well as digital microscope images of the before & after.

I don't typically send them out to customers post work, and use them more like a "break glass in case of emergency" type deal... You know, in case I get that unsatisfiable customer.

But I got a good review from the customer, so it all ended up well. But I'm always thinking of how to recreate good results more consistently and predictably in future.

Totally agree with you Nick.

I think a bit of background to this "theory", is that I'm still working on a framework to categorise my sharpening services pricing for my business, as well as streamlining workflows.

Almost all my customer knives have required repairs of different extents, and I was tired of doing these repairs without getting properly paid.

So I developed a framework (that included estimated bevel height) so that I could consistently move customers towards the appropriately priced service tier, to be fairly paid.

So when receiving knives, I measure the behind-edge-thickness, estimate the bevel width, and let them know what the final product will look like. Most of them gauge the quality of service based on the appearance of the knife (strange, I know) I still find it odd how my sharpening business really picked up after I got a bench polisher.

So, for this knife in conversation, I told the customer beforehand that the recommended sharpening angle range (15-20 DPS) would produce a bevel of 1mm width or less, and it would be hardly noticeable. And if she was agreeable with it, then I would proceed with work.

I actively try to avoid getting into disputes with uninformed customers who receive their knives post sharpening, and ask me why almost nothing was done, because they didn't notice any significant difference. (When handing over knives, I typically do a paper cut test in front of them, before they make payment. Using my PT50A test results just goes over their heads, but they can recognise a paper cut test)

So thinking back, my question was more of dealing with customers and what standard of work was deemed "acceptable", in a commercial sharpening context.

Many thanks for the responses.

I'm already done sharpening the chef knife, and the edge meets my standard of sharpness.

I think I was more curious about what kind of "standards" professional sharpeners work towards, especially when adding uninformed customers into the equation.

Regarding the bevel width, it's just my working theory that if the bevel width is too narrow, then the knife would have more difficulty slicing softer food (like meat) because before the bevel can start the cut, the primary bevel would be trying to wedge itself into the food. If the bevel width was too wide, then it becomes more vulnerable to rolling over/folding. So it's just based on observations from customer knives, my own knives, and brand new knives in stores, that I try to work towards a 1-2mm bevel width.

Good point, I asked about how to sharpen, but the focus of the question was not exactly aligned with what I asked.

Part one of question:
Seeking advice on how other Tormek users would sharpen a knife with an extremely thin blade (0.5mm behind edge thickness)

Part two of question:
Would a <1mm secondary bevel width be considered acceptable? (I typically aim for 1-2mm bevel width, in conjunction with the sharpening angle)

This knife is already sharpened at 15 DPS, but the secondary bevel is <1mm wide. So I'm just looking for advice if this is commonly done, or generally considered too narrow.

Just on a hunch, use a marker pen to mark the secondary bevel on your Japanese knife, and try a few light passes. See where the marker has worn off.

I typically sharpen Japanese knives at about 10-12 DPS.

My suspicion is that your sharpening angle of 15 DPS may be a bit too obtuse for the original edge.

A customer recently handed me a few knives for sharpening. Among the 5 knives (all Anolon brand), 3 of them have deep grind marks along the entire length (I'm going to guess it was from a bench grinder)

What I've done so far for the chef knife in question:
- Polished the entire blade to lighten scratches and to reduce the visible impact of previous grinding.

- Reprofiled the blade with the SG-250, and reduced the full bolster's width/length to match the blade heel. (The knife was banana shaped, with two knife bellies on the blade.)

- Sharpened with the DC-250 & DF-250 at 15DPS, honed with LA-220.

My question:
How would you sharpen a chef knife with a behind edge thickness of approx. 0.5mm? (No error, it's 0.5mm) I've tried and the secondary bevel is approx. 0.8-0.9mm. Would you consider a secondary bevel so narrow to be "complete" or "sharpened"?

Attached image is before sharpening.

[Me:]

My latest encounter with customer logic:

Me: Your knife tip is broken, do you want to repair that? There's an additional cost to grind down that section.
Customer: No no, there's no need. I don't use the knife tip.
Me: *thinks about knife constantly getting caught on cutting board* Okay

Me: Your cleaver has a lot of rust on it, do you want to remove it?... Or do you have any polish at home to remove it on your own?
Customer: Hmm... mmm... The rust is fine, no need for removal.
Me: *thinks about all the bacteria and food getting stuck in the blade, and rust flaking off onto food* Okay

Customer: I tried sharpening the cleaver on my own, but it couldn't pass the paper cut test.
Me: Yeah... It's a meat cleaver. It's got a very wide edge angle and made of softer steel because it's designed for breaking and splitting food apart, like a tiny axe. It won't really pass your "paper cut test" because the angle is really wide... What have you been using it for?
Customer: It was given to me brand new, unused. I haven't used it yet.
Me: *thinks about repairing yet another botched sharpening* Okay

Customer: After your sharpening, my knife looks very different, seems smaller!
Me: Yeah, knife sharpening works by carefully removing metal to create a sharp edge. All knives get smaller during sharpening, never bigger.
Customer: Ah yes, it makes sense.

Edge retention is still something that is somewhat of a mystery to me.  I have tried 600 grit and very little honing to highly polished.  Neither seem to be superior in terms of edge retention.  That is, retaining a 70 edge on the BESS.
After use, all steels I have sharpened lose that super sharpness in the first couple uses.  Some steels jump to a 140, some to 240 on everything but the softest foods.
They all seem to lose that eye popping sharpness very quickly.
I only have my tests to gauge this on.  I haven't seen any tests for real world usage to measure how fast the edge degrades.  I suppose CARTA tests do show the degradation but usually they demonstrate how long the usable edge lasts, not how long they stay ultra sharp.
Once again, how sharp you need/want to keep your tools/knife is very personal.  I had a carpenter look at a chisel sharpened to 90 like it was meh...

One thing I discovered during the course of my knife sharpening business, is how some customers reject modern sharpening methods (like my Tormek T8) to validate the methods that they've been using for the longest time as still "the best".

So the carpenter treating your 90 BESS sharpening as meh, may very well have nothing to do with your processes & results, but more to do with him trying to validate what he's always been doing as still "the best". A real life example, is how a local butcher turned down a free sharpening from me because he only believed in his own sharpening methods. His knife had only been thinned, no secondary bevel left, and the mystery whetstone he was using was like a misshaped bar of soap.

Another example was how a restaurant owner who was proud of learning how to sharpen knives since he was 14 (he was in his 50s when we spoke) but couldn't define what "high carbon steel" was, had no concept of knife geometry, as well as knife anatomy. The biggest indicator to me was when I offered to do a sharpness test on any of his knives for free (using my PT50A), and he immediately refused. That told me that he was rejecting me not because my methods and case studies sucked, but he was more worried that I would make his knives actually sharper, and totally invalidate everything he thought he knew.

Looking at your images, the bevel looks a bit rough for a blade that went through the SJ grindstone.

It seems like the gap between your grindstone grit size may be a bit wide. The last knife I sharpened was an Ikea 365+ knife (soft X50CrMov15 steel) My second last grindstone was the DE-250 (1200G) followed by the SJ-250 (4000G), then honed on the LA-220. I tested on my PT50A and got about 108.

My workflow has the knife go through 360G, 600G, 1200G, and sometimes 4000G. I have no insight into your CBN grindstone, but from what you wrote, it seems like you spent more time on the much higher grit (honing). I think it would help a lot if you used a 1000+ grit grindstone somewhere in your workflow.

Interestingly I find most folks seem to care less about their knives.  I charge about double what most knife sharpeners in my area charge.  My grinding isn't perfect, but I try to make them perfect every time.  That's why I charge more, I sharpen every knife like they are mine.  It takes time.
(And only you and I know they're not perfect)

I recently reviewed my pricing, and I created a framework where I would try to find a balance of two main factors.

The first factor was basing the average time spent per knife on an hourly rate, and how many knives I can sharpen within the work day.

The second factor was my pricing compared as a percentage of the cost of knives purchased by my target market. (People who buy German & Japanese knives, middle to upper range)

So now, whenever I get a customer who's holding their dull Japanese knife they had dropped $300-$400 on and complaining that my services are expensive, I ask them "Expensive as compared to?... It's either $40 to restore your knife, including polishing the blade and oiling the handle, or dropping a few hundred dollars for a new one"

The lights usually come on in their minds and they see the comparative difference.

My philosophy is that I wasn't involved in trashing the knife, so I'm not going to share in the cost of fixing it.

I think it's quite common for Tormek T-8 users on this forum to sharpen with the grindstone spinning towards the knife edge (called edge leading) I run my own sharpening business, and I sharpen almost all customer knives edge leading as well.

The grindstone spins only in one direction, and the way the T-8 drive system is designed, I don't think it'll spin in the opposite direction consistently even if you cracked open the machine and reversed the polarity of the electric motor.

Don't sweat the diamond grindstone getting damaged with edge leading sharpening. The diamonds are electroplated onto the steel hub, and is pretty robust (think of it as "gluing" the diamond dust with another metal... Tormek uses nickel I think)

I do sometimes sharpen edge trailing (grindstone spinning away from knife edge) when I've ground a distorted knife edge flat, and have a square edge where the cutting edge was. I'm still not too concerned with the knife edge damaging my diamond grindstone, but more cautious about the edge catching onto the grindstone, and the entire knife gets thrown away from me.

If you're concerned with damaging the grindstone with edge leading sharpening, I propose starting with light pressure and a small knife (3-4 inch blade) to get a feel of the grinding process. 600 grit against a blade will give some "pushback", but still waay easier to control than a dull blade on the 360 grit diamond grindstone.

I'm gonna guess you're referring to the SG-200 grindstone?

You didn't mention attempts at truing the grindstone after sharpening your chisel... So maybe that could be a good place to start?

I'm not the kind to stick up for any brands that make crap, and disclaimer, I don't own a T-4 (I only have the T-8) But that being said, the strengths of Tormek machines are their simplicity in design, and manufacture to good tolerances.

Take the time to practice with your machine. Get a feel for how the blade vibrates in your hands, the sound it makes during sharpening, and the speed of how it abrades.

My learning experience with my T-8 has been in waves. I started out getting really good results, then it all goes to shit, then I get better results, and then it all goes to shit again. But over time with increasing practice, the mistakes I make become increasingly rare, and only occur in unusual circumstances (E.g. More brittle steel encountered where it should be softer, steel suddenly wearing down a lot faster on random spots)

Since you don't really have an alternative you could use right now, and the T-4 is already with you... Why not try again on other items like knives? You get your practice in, and the worse case scenario? You have more sharp knives than you actually use.

I know what it feels like to have high hopes and that excitement when you get a new capability, and to feel that disappointment (and frustration) when it seems unable to do seemingly simple tasks.

Put in a bit more time, be patient and let the grindstone work it's magic. You got this.

I've been hitting my water trough lifting mechanism with PTFE spray grease after it got gummed up with the ACC-150 solution. So far it's been working pretty well, and each application lasts a few weeks of sharpening before I need to hit it with the spray grease again.

No luck removing my T-8 housing for a deep clean either.

Will be keeping an eye on this post for any useful information.

Anyone ever used their diamond wheels for grinding glass?  Diamonds supposedly cut everything and may be the only thing that would work on glass.  Only talking about taking small amounts of of an edge.  I'm thinking on the flat side of the wheel.

I think the issue I'm facing is somewhat relevant?

If you grind glass on your grindstone, and you get any pieces embedded in the stone, it may come back to haunt you when you're sharpening knives?

I have this mystery protrusion on one of my diamond grindstones where it randomly makes a distinctive rectangular chip on knife blades that I sharpen.

I've cleaned my diamond grindstones with my ultrasonic cleaner, and added more permanent magnets to my water trough, just to reduce metal contamination. But there's always this mystery protrusion that makes the same sized chip at random times. I think it's on my DC-250, but no luck figuring out where it is, and it doesn't show up consistently enough for me to definitively say on which grindstone it's on.

So yeah, if you can't pull any remaining glass off with magnets, and if you can't visually verify that it's all gone, then I think you roll the dice with grinding something harder than steel and also non magnetic.

I use an old tall and skinny glass jam jar with a piece of foam wedged into the bottom. I just insert the knife, fill with whatever cleaning agent I want (typically dishwashing detergent) and immerse the jar into the ultrasonic cleaner filled with water.

This setup allows me to use different cleaning solutions at the same time for different knives, and makes cleaning up a lot easier.

Nice, thanks for the tip. Could you share a pic of your setup ? I just ordered a 15 liter cleaner, so I probably will have to use a similar setup to avoid using 15l of water+solution for each knife batch. I will also use it to clean pasta dies, with warm water and dish soap.

Unfortunately I'm quite dumb with posting images here, especially with the hyperlinks and online hosting deal. But I can share my equipment used.

Ultrasonic Cleaner
- Elmasonic S 100H (Model 1002279-C)
- Capacity: 9.5L
- Functions: Timer, Sweep (2 frequencies), Degas

The beauty of the ultrasonic cleaner, is that you only need to have your item completely submerged in your cleaning solution (well at least the parts you want cleaned)

It will still clean effectively if you place a much taller container that protrudes above the ultrasonic cleaner main tank water level, and the water level in that container is much higher (above the tank)

I've used mine to remove calcium build up from shower heads, my Nespresso milk frother, electric toothbrush, sports watch, eyeglasses, tools, lots of customer knives (post polishing with compounds), and even my Tormek diamond grindstones.

For cleaning diamond grindstones, I just use a plastic container and water. Post ultrasonic cleaning, I run them on my T-8 with the water trough filled with the ACC-150 to "treat" (or coat) them, drip dry, and store. It works great on the coarse grindstone (DC-250), but the DE-250 usually needs a bit of brushing with an old toothbrush. No corrosion so far after 3 cleaning sessions.