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#11

General Tormek Questions / Re: moving to the stone grader

Last post by tgbto - March 16, 2026, 05:08:53 PM

As mentioned in the TT-50 topic, I believe the stone grader actually brings the stone out-of-true faster (which then requires truing).

Hmmm... I wonder what leads you to this belief?

Well, the "short" answer is : the stone grader has no reason to be held parallel to the USB. And there is no reason for the pressure applied by any hand to be equal to whatever is required to keep the stone true (or bring it closer to true) at any moment in time.

To elaborate a bit, having a human press down on the stone grader with the wheel turning is inherently an **instable** process, as whatever defects will be amplified instead of smoothed:
If the wheel has a low spot, the tool will follow the shape of the wheel and the pressure will increase when the surface of the wheel starts to rise right after the low spot. Conversely, the pressure will drop slightly shortly after the beginning of the low spot and shortly after the end of the low spot. The result will be to dig a bit into the stone at the lowest point, and grind a bit less around the high spots.

The delay in response between the cause and the effect is a perfect way to create oscillations (so called Pilot induced oscillations are an endless source of ... "interesting" situations in aviation or otherwise). Mixing oscillations and instability will not result in a nice result.

The fact that the tool is held by both hands compounds the previous phenomena by introducing variations not only along the circumference of the wheel but also between the internal and external shoulders of the wheel surface at any given point along its circumference.

This is not unique to the stone grader : if used in an uncontrolled fashion, the diamond plates may also create such undesirable effects, although holding them in the SE jig reduces the sideways variations. For a process to bring the stone closer to true (or at least no farther), you have to dampen the oscillations and bring the result closer to whatever "true" means, in this case : any point of the surface of the stone is at the same distance from the USB. The TT tool is well suited for that, the more recent version being less prone to oscillations.

I often use a diamond plate with the far end resting over a second USB, so I can both control the height precisely and grind the high spots first. Whatever flex remains in the setup (or non-parallelism between both USBs) is still a source of out-of-trueness, but it is still better overall.

Oh, and I agree 100% that sharpening brings the stone out-of-true. It does so because the edges being ground are never parallel to the USB, and they are often narrower than the wheel. I'm sure every Tormek user notices some slight variation of the noise or the water flow, that gets repeated with every turn of the wheel. That's a sure sign we're creating low spots.
Still, the steel edges are usually softer than the stone - for obvious reasons - whereas the stone grader is harder. So the latter is very good at rounding out the shoulders of the wheel, but also at bringing it out of true.

#12

General Tormek Questions / Re: moving to the stone grader

Last post by Herman Trivilino - March 15, 2026, 07:21:42 PM

As mentioned in the TT-50 topic, I believe the stone grader actually brings the stone out-of-true faster (which then requires truing).

Hmmm... I wonder what leads you to this belief?

It's quite possible that you're right. It could also be true that the act of sharpening brings the stone out of true. Certainly something must be causing it to happen, since we know for sure that it does get out of true.

Again, I go to my automotive disc brake analogy. Just as the brake pads, and to a lesser extent the rotors, are designed to wear, so is the grindstone. Using it makes it wear. Things like using the stone grader, using the truing tool, or even the very act of sharpening a tool itself, will make the make the grindstone wear faster, so will driving your automobile make the brake pads and rotors wear faster.

This is part of the design of these things. It's how they function. It costs money to operate these devices because of this wear.

#13

Knife Sharpening / Re: 3D printed pre USB setup

Last post by RichColvin - March 15, 2026, 04:57:06 PM

How do you envision these being used?

#14

Knife Sharpening / some subtle information about ...

Last post by Ken S - March 15, 2026, 01:35:10 AM

This video features two knife experts using a Tormek. Oneof them is Thomas Ericksson, grandson of one of the founders of Morakniv.

https://youtu.be/iYsgxerFKHk?si=fDHKgjQ8N_4QRb_W

Ken

#15

Knife Sharpening / 3D printed pre USB setup

Last post by Nik3 - March 14, 2026, 12:40:56 PM

Good day gentleman and ladies!

After getting back to sharpening again after my first kids (twins)

I started thinking.
3D printed pre USB setup, anybody tried it?

I have my first test now for the fvb with standard project distance 130-140-150 and DPS at 15. For the Tormek leather wheel.

Please come with critic so we can evolve together!

Best regards
Niklas

#16

General Tormek Questions / Re: expanded TT-50 thoughts

Last post by Herman Trivilino - March 14, 2026, 04:10:31 AM

I'm not sure the truing tool restores the "cutting efficiency" of the stone.

I guess it depends on what you mean by efficiency. A freshly-trued stone definitely cuts steel more aggressively. I wouldn't sharpen a good knife on a freshly-trued stone. It removes too much steel from the knife blade. I would find my dullest chisel, lawn mower blade, or other tool to sharpen on a freshly-trued stone. In fact, I often keep a dull tool handy to be sharpened immediately after truing.

Ken is absolutely right about truing often and lightly. Not only will it give you better results, it's more economical. Because an out-of-round grindstone will very quickly get more and more out of round as you use it and you will have to remove a lot of material to get it round again. A grindstone will last longer if you keep it from getting out of round by truing it often.

It's kinda like brake pads and rotors. Putting new pads on a rotor with a rough surface will make the pads wear faster. It's more economical to machine the rotors when replacing the pads.

#17

General Tormek Questions / Re: SJ Wheel wheels rant

Last post by Herman Trivilino - March 14, 2026, 03:46:49 AM

Well, jeez. Not sure how I missed this reply.

If I ever have the chance to award a "Popular Mechanics Home Workshop Practical Sharpener" award, you would be the recipient.

High praise indeed! Thank you Ken.

My memory is fuzzy. Was I the person who offered you the loan of my SJ-250?

Ken

Yes, indeed. It was you.

#18

General Tormek Questions / Re: expanded TT-50 thoughts

Last post by Ken S - March 13, 2026, 07:12:55 PM

TGB,

Your points are well taken. It may surprise you; however, I agree with you. In my own sharpening, I use a set of three DMT diamond cards. Each is epoxied onto a piece of steel 2" x 8" x 1/16". This was a piece of 2' steel from my local hardware store cut into thirds. These are placed into older square edge jig (s).

I fully credit Wootz for conceiving the idea o using diamond plates to keep grinding wheels true and graded. I consider my minor modification a small improvement. Wootz' premature passing was tragic in many ways. Who knows what concepts Wootz would have developed with a longer life.
believe both truing and grading are developing concepts. I do not believe either Wootz' concept or my modification will prove to be the end all.

I often do not know the experience level of the members involved. Some members, like you, are obviously more skilled than the majority of the membership. I suspect most members are still using the stone grader, many using it very infrequently. For some, I believe these suggestions might be a step up in their technique. I encourage more advanced posts like yours. It will help us all grow.

Ken

#19

General Tormek Questions / Re: moving to the stone grader

Last post by tgbto - March 13, 2026, 10:30:49 AM

As mentioned in the TT-50 topic, I believe the stone grader actually brings the stone out-of-true faster (which then requires truing). So it seems to me its effect is somehow contrary to the truing tool (except in its ability to coarsen the grit, albeit very temporarily).

I highly recommend using the truing tool with care, and diamond plates to adjust the grit of the SG stone, as mentioned in numerous topics on this forum and as demonstrated by the late Wootz on YouTube here and here.

#20

General Tormek Questions / Re: expanded TT-50 thoughts

Last post by tgbto - March 13, 2026, 10:23:36 AM

I'm not sure the truing tool restores the "cutting efficiency" of the stone. It's not as if the SG won't sharpen anymore if not trued for a long time. It will probably not sharpen squarely, and might create low spots on knives or planer blades and such.

The stone is more aggressive after the truing tool is used because of the temporary low grit, but that will quickly settle back to the standard average SG-250 grit. The truing tool ensures the surface of the wheel is parallel to the usb, with a constant diameter.

Sharpening technique, as well as the kind of tool getting sharpened, will have an impact on how the stone wears down, and how its geometry is impacted in the process. It will therefore require more or less frequent truing, but not because the abrasives cut less efficiently.

So I don't think it's a matter of what the average cutting efficiency is, but rather how close the wheel is to its optimal shape. Too high a pressure will exacerbate high spots and low spots, narrow tools will quickly create ridges on the stone. The sharpeners' skill (in keeping pressure optimal, using the full width of the stone, keeping tools square with the wheel, etc.) will increase the time in between two truing sessions.

Also, careful use of a diamond plate in the SE jig will keep the stone parallel to the USB for longer periods, and skill or the use of two USBs will reduce the risk of low spots.
In my experience, the use of the grading tool degrades the shape of the wheel quickly, requiring much more frequent truing. This is because it is very hard to keep it parallel to the USB (after all, why would your hands be parallel to the USB ?), and it is used roughly at constant pressure, which will tend to dig into the already low spots.

When I sharpen knives only and use diamond plates once in a while to temporarily change the grit of the SG, I barely feel the need to true at all. This increases the lifetime of the SG in the long run.