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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.

As for using those cleaners with knives, I think one would have to create some kind of holder to keep the blade immersed, but clear of the walls and floor of the tank. I'm thinking electrical wires to support the handle and spine.

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.

"Wow, the scores you mention before using the USC are impressive. Like 80 without stropping. Thanks for the answers, and you got me wondering what a suitable USC would be and what it costs... I've been looking around and saw some 6 liters dual transducer 40kHZ cleaners around 250 EUR."

From personal experience, go for the largest capacity ultrasonic cleaner you can reasonably afford. I guarantee you'll be throwing a lot of other items in it once you've experienced what it can do.

If you're able to inspect the blade post ultrasonic cleaning with a microscope, and the scratch pattern remains unchanged (or the cavitation has created markings shallower than the existing scratch pattern)... I think you have a winning combination 👍🏻

On my day-to-day knives, when they need it, after a couple passes on the DF-200 and a few more on the strop, they are as sharp as ever.

What I do with my personal knives, is whenever they start to feel dull, I start them on the leather wheel first. (I use a knife jig and not freehand) Only if they still feel dull after honing do I sharpen them on my DF-250. Most of the time I get by with just the leather wheel only.

The worse I get are chips from careless use.

One knife from a chef had a crack between the handle and blade because he had been using it to "slap-flatten" meat. The handle points to one direction, and the blade in another.

One home cook was using a cheap meat cleaver to chop through beef and pork bones. The blade was not only chipped (>5mm chips), but also warped.

A professional Michelin star restaurant chef was "sharpening" his $200+ Japanese knife with a 3000 grit whetstone and a honing rod. His "skills" made the middle section of the blade significantly thinner.

Another home cook had been sharpening her Chinese cleaver on a soap bar shaped whetstone, creating a concave blade.

A butcher just kept thinning his blade on a rounded whetstone, so there was no secondary bevel at all, and the blade kept flexing during sharpening.

A home cook allowed his Japanese knife to corrode so badly, that after corrosion removal, the blade was slightly thicker than aluminium foil.



I should start charging more for my services (or start slapping people in the face)

I believe the 10 degree angle is from the jig that holds the scissors. If you look at it from the side, you'll notice that the clamps and base are not completely parallel.

On a side note, I had recently sharpened a pair of hairdressing scissors. They were some Japanese brand with that clamshell-shaped blade profile.

All I knew was that the hairdresser had set it aside because it had gotten dull, and it cost her about $200 for that tiny pair of scissors (barely 15cm in length)

I scrutinised it under my digital microscope, looking for areas with a consistent scratch pattern (to know how it was sharpened) Then I just pressed the inner side of each blade against the side of my SJ-250 for about 2-3 minutes, cleaned it up and reassembled it.

She said it was as sharp as brand new, but was not using it as frequently as before. (It was a shop rental/leasing issue, not the scissor sharpness)

From my limited personal experience running my own sharpening business...

If it's the first time your knives are meeting the T8, save yourself time and start at 220/360 grit. Reprofile the entire edge and work your way upwards to your 1200 grit (LA-220 inclusive)

When they start to feel dull again, start with the LA-220 first, before you decide if you want to break out the grindstones for (re)sharpening.

He laughed and replied that his contacts could get the knives ( I think they were Victorinox) cheaper than the sharpening (which I doubt).

The argument for getting something "cheaper" only makes sense if it's a like-for-like comparison. Like maybe getting the same model Zwilling chef knife at a lower price from another vendor.

If there's someone else using the Tormek and producing the exact same results as me, I'd openly tell the customer to go for whoever is cheaper.

But the most bizarre still has to be the customer who had been doing a hatchet job on his own knife and ground it out of shape with his own honing rod and rolling sharpener. (The knife belly was basically gone and became a straight line)

He handed it to me for sharpening and I re-ground the entire blade back to its original shape, reprofiled and sharpened it to below 200 BESS (from 700+) And still he felt compelled to sharpen it some more to "make it sharper" the very next day I returned it to him (after only one day of use).

Lessons learnt during the brief time of my new knife sharpening business... Let me share the hilarity.


If the knife shows any signs of customer sharpening, it'll 100% need to be reprofiled.

Customers buy knives based on how they feel, and decide how to use them later. (I get to see a lot of bizarre damage)

If anyone brings me multiple knives of the exact same design, from the same household, I know they'll destroy all the knives I've sharpened within a week.

Professional chefs often have no idea how to sharpen their own knives.

All my customers who spoke about high carbon steel, have no idea what it is.

There are customers who do years of damage to their knives, and want it remedied within an hour.

The most common remark about my business is "Why sharpen knives? Just buy cheap ones and throw them away"

Customers lie to me about their knife usage, like how people lie to their doctors.

Every whetstone a customer has shown me was shaped like a used bar of soap.

There are customers who bring dull knives to me (700+ BESS), I sharpen it to below 200 BESS, and they'll still sharpen it after I return it to them. (One customer actually said he did that to make it sharper. Yes, the same method that he dulled his knives with, he used to make my sharpening "sharper")



I often ponder how these things still happen in the year 2025.

For my sharpening setup (T8), I use mainly diamond grindstones. I typically use the DC-250 (360G) for first time customers to reprofile the edge, sharpen with the DF-250 (600G), then refine the edge with my DE-250 (1200G)

That being said, my context is different from yours as I typically sharpen individual customer knives, and I have emphasis on the "wow" factor to increase repeat orders.

If you've already done the heavy lifting of reprofiling all their knives with your T4, and will be the only person sharpening their knives, then I personally recommend the DF-200 (600G) diamond stone as having the most bang for your buck in keeping their knives functionally sharp.

Additionally, I've used the 600G diamond grindstone to reprofile blades, but it does take a much longer time (compared to the 360G) If you don't foresee yourself sharpening individual customer knives like me in the near future, I'd say the DF-200 would suit your needs for your current context.