Thread: Definition of Hardness in Water stones & Sigma Power Stones

I received the first part of my Sigma Power Stones that I ordered from Tool From Japan. I have posted my first impression in my blog here.

Ta TS. Sounds good.

The 8000 is JIS rating I take it, so about 1 micron?

I posted Stu a query about stones for lapping of plane blades, 120g Sigma or 1000g Bester. Here's his reply

The Sigma #120 is a very aggressive stone that should be used for grinding out chips in the edge more than anything. It is one of, if not the hardest of the coarse stones, but they really are not designed for flattening. They will do it, but I sure wouldn't want to be grinding out the resulting surface. These things scare me, just taking them out of the box to inspect them for cracks and chips, they really do bite.

The Bester #1000 is one of the best stones for maintenance work, where the blade needs to have it's geometry restored to a usable condition. Reshaping bevels and minor flattening. While it is fast, hard and an amazing stone, if the back is not already reasonably flat, you might be there a while.

For something like a manufactured plane blade that should already be close, the Bester is ideal to taking out the grinding marks. For something that needs serious work, then I highly recommend using another method, be it loose grit on a lapping plate, sandpaper on a flat surface or a diamond plate.

The newer plane blades such as Lee Valley, Lie-Nielsen and Hock, et al, the Bester may not even be required for the back, but with use, yes it will be required.

I usually get maybe 3-5 touch ups from a fine stone before I go to a medium stone such as the Bester, and at that point I will re-establish the bevel geometry and give the back a few swipes to make sure it's not getting out of kilter.

In your case, I assume the A2 blades are one of the above, and the HSS are either Mujinfang or some blades that Helmut has organized, then I'd have to say the Bester will be most useful.

I hate trying to 'sell up' anyone or anything, but in your case, it's best course.

FWIW my two Hocks have had to be lapped; a number of Veritas blades were flat or v. close to it.

I have a DMT Duo coarse/fine but that's had a good deal of work and I plan now to keep it just for flattening other stones.

I would assume that is rated with JIS.

According to the JIS (Japanese Industrial Standard) rating an 8000 grit stone has a between 1.5 to 0.9 micron's abrasive particles. Examining the micro-bevel, I could see sections of very uniform, mirrored like regions. However spaced at regular intervals the bevel exhibited deeper furrows. This irregularity can be accounted by the known variance in grit size within a single stone.

Regarding the 120 grit Sigma stone, I took a chisels that was in a very poor state, and gave it a small work out (80 strokes) trying to flatten the back (which it did). Lets just say, that its like having a belt sander in a stone. It was like flattening the back on 40 grit paper that never looses its initial aggression. I would not recommend it for flattening anything close to flat. I intend to use mine as a flatten stone.

Sounds good Helmut.

I've ordered a Sigma 8000 on the basis of your blog report, and a Bester 1000.

Originally Posted by rsser

Sounds good Helmut.

I've ordered a Sigma 8000 on the basis of your blog report, and a Bester 1000.

me and my big keyboard. I am sure that you will be impressed. I look forward to seeing what your experience with them are.

No need to do a 'doh'! That was a very precise report. Thanks again for the link.

And it's good to have Stu's advice. He knows whereof he speaks. Along with Neil and you; that makes us fortunate readers.

Thanks TS. A good read and looking forward to your further review.

On mirror vs misty finish, I'm a misty man now. All the deep scratches have to be gone, but I like a finish that sparkles rather than gleams.

That circular action is the way I learned to sharpen (the western way), but now work straight up and down the full length of the stone gradually working the width of the stone and rotating ends to more evenly distribute the wear pattern. Instead of one deeper depressions in the middle of the stone, this gives (for me anyway) two shallower longer parallel wear areas along along the stone. These require less stone to be removed to restore flatness and lengthens the life of the stone.

Ern, thanks for copying us in on Stu's reply on waterstones for lapping. I have a Sigma #120 for major rehab jobs, but must admit that I rarely use it... a bit agricultural, and in fact prefer the King #300 for less demanding rehab work and the belt sander for anything really serious.

Will be very interested to hear how you find the Bester #1000. I'm thinking of getting one myself to replace one of my #1000s (an old King that is quite aggressive, but as we all know quite soft and high maintenance, which I have passed onto one of my sons as part of their kitchen knife sharpening starter kit).

Hope you both enjoy your Sigma #8000s

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How do you use the belt sander Neil?

I can see the advantages in speed but hesitate to try it.

As for back flattening to minimise stone hollowing, I've just come across an article by Charlesworth that's v. instructive. TS and Neil, PM me your email address if you'd like a scan.

Ern if the Charlsworth article is the one of waterstones by Fine Woodworking magazine. Then I already have it.

If you search long and hard, their are so many articles on water stones, and many contradict the other.

One common way to flatten a stone is to stick some abrasive to a lapping plate and then rubbing it back and forth. Which works however it has a problem.

Because all our bodies are asymmetrical in motion the stone will be flat but it is very easy to make the stone un-parallel. This then becomes a problem because as you sharpen you will need to push the blade more on one side, to compensate for the slope in the stone.

The article is titled 'Avoiding Hollow Waterstones' and was first published in the Furniture and Cabinet Making magazine. Republished in a UK Guild of Master Craftsmen collection titled A Guide to Hand Tools and Methods.

Yeah, it's a finicky business.

Ern - I have sent you a PM with my email address.

The 1000 bester and 2000 Sigma came today.

I will do a full review on the weekend.

Both stones are significantly harder then the 8000 grit Sigma power stone. The 2000 being the hardest of the three. You can really feel the resistance 1000 Bester and the 2000 Sigma stones give when you try to flatten them. In comparison the 8000 Sigma feels soft.

Both the 1000 Bester and the 2000 Sigma where not absolutely flat, either having high spots along one corner edge. I was able to flatten the 1000 Bester with ease but the 2000 Sigma is very hard, and it will take some time to level it off.

Both stones produce very little muddy slurry however they go grey very quickly, meaning that they remove metal quickly. I soaked each stone for about 3 minutes, that is all it took for the bubbles to stop.

Stu was kind enough to throw in a very handy water bottle with a curved straw, that comes to a point at the nozzle. It makes adding water to the stones a breeze. Flattening the 1000 Bester and the 2000 Sigma is non issue as neither stone seems to wear to any great extent, during use.

I redid two blades on a combination of the 1000 Bester, the 2000 Sigma and the 8000 Sigma. The finish (Uniformity of scratch patter) I was able to get from these three is significantly better then what I can get from a 800, 1200, and 6000 grit sets King of waterstones.

The only thing I will add is that the jump from the 2000 Sigma to the 8000 Sigma may seem like a big leap however the 2000 Sigma performs well above what you would expect from a 2000 grit stone and the 8000 grit Sigma Power had no problem removing all of the deeper marks left by the pervious stone.

In my time I have used a few sharpening systems, scary sharp, diamond plates, diamond pastes and king water stones. I am confident in claiming that these Bester and Sigma ceramic water stones have given me by far the best edge, I have ever had.

In my review I will use three Lie-Nielsen bench plane blades. I will finish one using a combinations of King's, another on using Diamond plates and the the third using the Bester and Sigma ceramic stones. While it will not be a comparison of stone grits it will serve to illustrate the difference between the three systems.

Originally Posted by rsser

How do you use the belt sander Neil?

With great care! .....:said with tongue in cheek:

Actually it's easier than you might think. I wouldn't use it for flattening the back of blades as the platen under the belt is just not flat/firm enough, but for restoring the bevel on blades that have a bad nick or need a new geometry it's very effective. Start with the finest belt grit you have (can't remember what mine is) and go cautiously until you get the feel of how rapidly each grit size removes the steel......AND, no need to say, work with the belt running away from the edge. Perhaps start with an old blade you don't care about...

PM sent with email address for Charlesworth article, thanks.

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Thanks TS for your initial review of the Bester and Sigma.

Yes, the 1000 and 2000 are much harder than the 8000, but you shouldn't have to work the 8000 that much as it's more of a polishing stone. My preference is to go to a 4000 or 6000 before the 8000. I find the jump from 2000 to 8000 leaves too much sharpening, and not just polishing work, still to be done on the 8000.

But people vary in their preferences.

Looking forward to hearing more on your Bester 1000.

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