beyond grading

[Ken S]

This week I discovered a new you tube by Knife Grinders about grading the grinding wheels. While diamond and CBN wheels have the advantage in longevity and maintaining a constant diameter, having the ability to alter the grain size is where the "Original" wheels really shine. I believe Tormek introduced the stone grader when they switched from the natural Gotland stones to the present man made aluminum oxide SG Super Grind wheels. The new SG wheels cut more quickly, but left a finish which was not quite as fine. The stone grader allowed the Tormek user to obtain both the faster cutting and smoother finish. It has been a fundamental part of Tormek technique ever since.

Here is a link to the you tube:

https://youtu.be/141hD1d1zj0

Wootz of Knife Grinders has used diamond cards for several years to dress and grade his conventional grinding wheels. This you tube demonstrates his latest thinking, a substantial leap forward. By using three inexpensive grits of diamond cards, he is able to safely and effectively grade all three conventional grinding wheels, (SG, SB, and SJ).
This was especially interesting to me, as I have found the stone grader less suited to the SB and SJ wheels than to the SG, for which it was designed. By using the 80 grit diamond card, he is able to effectively grade the SB to 220 grit. With the 1000 grit diamond card, he can grade the SB to around 600 grit. In the past, I have only been able to grade the SB to coarse by using the TT-50 truing tool. This is effective, but removes more stone.

The three grits allow the SG to be graded coarse, fine, and with the 1000 grit card, even finer. Wootz estimates 1500 grit.

The 1000 grit card is gentler with the SJ than the fine side of the stone grader. He recommends cleaning the SJ with a rubberized abrasive.

Parts of this technique have been previously discussed on the forum. Wootz makes no inventor claims, although he certainly deserves to be recognized as a prominent early pioneer.

As there are are more than three grits available, other possibilities may yet be explored.

I recommend this you tube. I have watched it three times already and am continuing to learn from it.

Ken

[Buckm]

I have purchased the Square Jig a #400 / #1000 / #80 grit diamond plate. Also an extra SG-200 as a dedicated 220 and will try and get the other SG-200 to be a 1500. If the results of the 1500 look like the microscope images on the video I would imagine the fine lines would not be so prevalent, before any leather honing.

[Ken S]

Bryen,

Don't forget to make your final passes with very light pressure to lighten the scratch pattern.

Good luck and keep us posted.

Ken

[John_B]

With the 1000 grit diamond card, he can grade the SB to around 600 grit. In the past, I have only been able to grade the SB to coarse by using the TT-50 truing tool. This is effective, but removes more stone.

The three grits allow the SG to be graded coarse, fine, and with the 1000 grit card, even finer. Wootz estimates 1500 grit.

Ken

This is confusing, is it 600 or 1500 with 1000 grit diamond card?

[Ken S]

John,

The 1000 grit diamond plate grades the SB blackstone to about 600 grit.
The same 1000 grit diamond plate can grade the SG to almost 1500 grit. This difference is because the SB is made of silicon carbide and the SG is made of aluminum oxide.

This is all covered in the linked video. (approx. 3:40 to 5:30)

Ken

[Buckm]

Ken
  The Graded SG-200 with the #400 and then the #1000. Made the bevel much smoother! You can feel the difference, + smaller wire edge, easier and quicker to polish to finish! Im not sure how long the metal 400/1000 will last but so far so good!

Bryen

[Ken S]

Well done, Bryen.

I think of stone graders as long term consumibles, like grinding wheels or brake parts. Also like brake pRts, I suspect they will last longer with experience.

Ken

[bisonbladesharpening]

Found a 150 and 400 on Prime for $17.50 us.  Lowes has a 7" x 3" Tie plate in the lumber section for $1.98 that fits
perfectly behind them and in the square edge jig.  Can't wait to play.
Best Wishes, Tim

[sharpening_weasel]

Hello all,

I recently watched the same video, and was wondering if a silicon carbide sanding belt backed by a flat plate of some kind in the square edge jig would work as well. The sandpaper is on the way, and I'll write an update once it gets here. I think this method, if it works, may be more economical while at the same time providing high quality material, and a greater range of grit sizes.

Cheers from mud city.

PS

There are a bunch of different options, ranging from ceramic, silicon carbide, zirconia, and aluminum oxide. I'm going with the silicon carbide, but I'd be curious if any of you think another option would work better.

[sharpening_weasel]

PS
There are a bunch of different options, ranging from ceramic, silicon carbide, aluminum oxide, zirconia, and aluminum oxide. I'm going with the silicon carbide, but I'd be curious if any of you think another option would work better.

[Ken S]

Jesse,

Interesting thought. Let's imagine a bit. (Caveat: I have no supporting factual evidence from Tormek supporting these musings; they just seem logical to me.)

Years ago, Tormek was using Gotland natural stone for the grinding wheels. They produced a fine surface, but were slow cutting. The new aluminum oxide (SG) manmade wheels nut faster, but did not leave as smooth a surface. The stone grader lets the SG work as the faster cutting stone (graded coarse) and as a finer finish stone (graded fine).

Looking at the silicon carbide stone grader, it looks similar to a typical two grit sharpening stone of the period. It would be a logical choice, a readily available, suitable product. Diamond and CBN were not used as commonly back then. I would think that almost any abrasive harder than the grinding wheel would work, depending on the binder.
Some abrasives would work better than others.

The introduction of the SB blackstone and the SJ Japanese grinding wheels added new sets of variables. I think we have a lot to learn and encourage experimentation and discussion.

Ken

[See Y Not]

After watching the video, I couldn't wait to try it out.  So I ordered a few diamond plates on ebay.  They were $6+ each.

1st question) Do you guys buy the cheap plates or the quality kind?

2nd question) How long to they last?  Cheap and quality

The ones I bought didn't last very long.  Think I got a poorly made 600 grit plate, because it was smoother than a baby's butt after a couple of sessions on the stone wheel.  The 1000 & 1200 lasted maybe between 4 to 6 uses.  The quality plates I've seen are somewhere between $40 - $60.  Don't know if they are worth it since I just bought a couple of CBN wheels, and they do not need to be graded.

[tgbto]

I see very inconsistent performance from the cheap ones. I have a cheap plain coarse one (#120) and a cheap #1000 with a hexagon pattern that hold very well (50+ uses).

A cheap 1200 didn't even last one use. I tend to think that 2 quality ones should be a wiser investment. I guess it once again boils down to buying good oats.