The mystery of SB-250

[Sharpco]

Tormek says...
"It does not offer faster steel removal on ordinary carbon steel than the Tormek Original Grindstone."

But Steve says...
"I have been using the Black wheel for several years now on my market machine, but have the original SG wheel on my teaching machine. My technique is freehand 90% of the time.  I do not grade the wheel but let it retain its natural state. I move on to non-Tormek finer wheels for the honing and stropping stages. I find that the SB wheel cuts 25 to 50% faster than the SG wheel and lasts half again as long. Most knives sharpen in 1 or 2 passes on the SB, 3 is rare. 2 and 3 are the norm on the SG and 4 is not that uncommon, 5 is rare. I was replacing SG wheels every year, SBs last a year and a half. The SB is definitely worth the premium for a knife sharpener, IMHO."(https://forum.tormek.com/index.php?topic=2541.msg13188#msg13188)


People's opinions about the SB's grinding speed are not consistent. Why?

I think that pressure and grinding direction can be variables.

What's your opinion?

[Ken S]

Interesting topic, Sharpco.

My opinion of the SB-250 blackstone is still being formed. Factoring in very strongly is the fact that people like Steve and Magnus Sundqvist use it very successfully. That alone is enough to convince me that it is a good stone.

My own experience with the blackstone has been frustrating. I need to spend a quiet sharpening session just working with the SB starting out with very light pressure, barely touching the grindstone and gradually add pressure. I have come to believe that very light pressure is the key to success with the blackstone. During earlier attempts with it, it glazed very quickly and stopped cutting. There was one positive side effect to this frustration; I became very skilled with the TT-50 truing tool. While I generally prefer multiple very light passes with it, I became comfortable making deep cuts. I also learned that it was faster to mount the TT-50 on a separate support bar and interchange them. I consider this work a dismal failure.

I am convinced that the problem lies with my technique. That is not excess humility or Tormek worship. If experts like Steve and Magnus like it, I look inward for the problem.

I also lay some of the fault on Tormek. In my opinion, Tormek has not updated its training to include the blackstone or the Japanese wheel. Like most of us, my primary training resource was Jeff Farris' well done videos. I remember Jeff lifting the side of the Tormek off the bench holding the chisel handle to show that the Tormek motor had plenty of power. We were encouraged to use heavy grinding pressure. That works well with the SG regular aluminum oxide grinding wheel. It will quickly glaze the blackstone. The last time I checked, the handbook had only a paragraph for the SB and SJ together. Video coverage has also been sparce.

We need to unlearn our SG mindset with the SB. Tormek has a fine studio now for making videos. In my opinion, an in depth video covering the SB (and the SJ) is long overdue.

Ken

[RichColvin]

Sharpco,

When my SG stone finally got too small, I replaced it with an SB a 2 or 3 years ago.  My reasoning is that I sharpen a lot of turning tools, most of which are high speed steel (I woodturn as a hobby).  The SB stone works superbly for that.

But, I'm expanding my pursuits into wood carving more, and those tools are generally high carbon steel.

The SB is now at 210mm, so I just ordered a new SG stone.   I think using the SG stone when the SB isn't warranted will be the best approach.  Will let you know in a year or so ...

Rich

[Ken S]

Rich, I think you are wise to order the SG while there is still useful life in your SB. That will let you choose the stone best suited to the job at hand. I don't understand why people wait until a grinding wheel is fully worn down if they plan to replace it with another kind of wheel. Like for like makes sense, but not different, It limits your options.

Sharpco, I would like to clarify Steve's statement. I asked Steve if he felt the Tormek could handle the entire sharpening process. He replied that it could. The reason he uses non Tormek products for finishing is for speed. In his case, at the farmers market, he would average a hundred knives in a Saturday morning. For a typical Tormek user, like me, who sharpens considerably fewer knives at a more relaxed pace, the Tormek can easily handle the entire process.

I would note that one of the reasons Steve's technique has worked so well for him is that he has focused his attention on becoming very skilled. I see that focus in you,also. Keep up the good work.

Ken

[Sharpco]

I also lay some of the fault on Tormek. In my opinion, Tormek has not updated its training to include the blackstone or the Japanese wheel. Like most of us, my primary training resource was Jeff Farris' well done videos. I remember Jeff lifting the side of the Tormek off the bench holding the chisel handle to show that the Tormek motor had plenty of power. We were encouraged to use heavy grinding pressure. That works well with the SG regular aluminum oxide grinding wheel. It will quickly glaze the blackstone. The last time I checked, the handbook had only a paragraph for the SB and SJ together. Video coverage has also been sparce.

We need to unlearn our SG mindset with the SB. Tormek has a fine studio now for making videos. In my opinion, an in depth video covering the SB (and the SJ) is long overdue.

Ken

I agree.
Tormek offers a great handbook, but I think there is a lot to add.

[Sharpco]

Sharpco,

When my SG stone finally got too small, I replaced it with an SB a 2 or 3 years ago.  My reasoning is that I sharpen a lot of turning tools, most of which are high speed steel (I woodturn as a hobby).  The SB stone works superbly for that.

But, I'm expanding my pursuits into wood carving more, and those tools are generally high carbon steel.

The SB is now at 210mm, so I just ordered a new SG stone.   I think using the SG stone when the SB isn't warranted will be the best approach.  Will let you know in a year or so ...

Rich

Rich.

I also have SB, but now I am using SG mainly.

[Ken S]

I have several editions of the handbook. It is a valuable resource. I like to trace the history of the Tormek and Tormek history. I consult it often.

The present handbook is essentially the same as Torgny Jansson, the inventor and founder, wrote years ago. Additions have been made to include the present jigs and accessories. What I find lacking are descriptions of technique modifications which have evolved over the years. What I would like to see a major rewrite which would include all of Torgny's original writings. In a different font or color, I would like to see all the advances in technique included. I would not want to lose Torgny's words. He is the spirit of the Tormek, however, Tormek has not stood still in products or techniques.

This would add to the length of the handbook, which is already too long for those with short attention spans. I would like to see a quick start guide for them.

Ken

[Elden]

   You believe in asking largely, Ken!      Is that similar to Psalms 81:10, ... open thy mouth wide and I will fill it?

[Ken S]

I do. I expect a lot from Tormek because they are a great company. I fully realize that they are a very small company, however, they have a knowledgeable staff, good connections (with experts) and a very nice newly built studio. Why not ask big?

Ken

[wootz]

The silicon carbide SB is much harder and denser compared to the aluminium oxide SG, and therefore longer wearing stone - all volume sharpeners prefer it for the longer life span.
However, you won't be able to grade SB as fine as you can SG, and for this reason when Steve and me and others use the coarse SB for setting edges and shaping bevels, we need a 2nd fine stone, either a finely graded SG or aftermarket Japanese #800 or CBN #1000

[Sharpco]

The silicon carbide SB is much harder and denser compared to the aluminium oxide SG, and therefore longer wearing stone - all volume sharpeners prefer it for the longer life span.
However, you won't be able to grade SB as fine as you can SG, and for this reason when Steve and me and others use the coarse SB for setting edges and shaping bevels, we need a 2nd fine stone, either a finely graded SG or aftermarket Japanese #800 or CBN #1000

thank God. I can give up the fine grade of SB, so that does not matter.

However, there is some opinion that the grinding speed of SB decreases faster than SG. Stig told me that strong pressure is the cause of it, do you agree?

[Ken S]

My standard cutting test of harder steel is to place a 5/16" square metal lathe bit in the square edge jig. I set it to grind a thirty degree bevel. Then I grind continually with firm pressure for five minutes. The reigning champion is the 46 grit Norton 3X wheel. The runner up is the 3X 80 grit. Both the 80 and 180 grit CBN wheels performed well. I tested these later, and may have used lighter pressure. The SG gave a respectable, but not steller performance, better than I expected for a wheel designed for carbon steel. The SB blackstone came in last. I can say that, in my experience, the blackstone does not perform well with heavy pressure. It glazes over and stops cutting.

Stig has told me my problem is using too much pressure. I believe him, and plan to redo the test with light pressure. In fact, I need to devote an entire sharpening session to the blackstone. I have not spent enough time working with it to really get to know it. In addition to learning about the effects of lighter pressure, I need to spend enough time using the stone grader with it to really know its effect on the stone.

I think you are slightly misinterpreting Steve. For his working set up, he does prefer the blackstone, for its longevity and speed. In the past, he used the SG enough to wear out at least eight wheels, which he uses as tent weights! His teaching Tormek set up in his shop, uses the SG. I do not know his thoughts on using the stone grader with the blackstone graded fine. I do know that he felt that using the stone grader was too time consuming for the high volume of knives and scissors he had to complete in a short time period. If Steve had been working in a slower work environment, I don't know if he would have added the extra equipment (and cost).

At this point, I must say that there are several questions that I can not answer regarding the blackstone. I can say that it does not work with high pressure. I hope other users will post. I begin with the premise that I do not believe Tormek would sell a product that they had not extensively tested and found to work. I have faith in Tormek. I have also read too many frustrated posts which have mirrored my poor results with the blackstone. Tormek needs a better product education with the blackstone. A well done five minute video on the website devoted to using the blackstone would solve many problems.

Ken

[Sharpco]

My standard cutting test of harder steel is to place a 5/16" square metal lathe bit in the square edge jig. I set it to grind a thirty degree bevel. Then I grind continually with firm pressure for five minutes. The reigning champion is the 46 grit Norton 3X wheel. The runner up is the 3X 80 grit. Both the 80 and 180 grit CBN wheels performed well. I tested these later, and may have used lighter pressure. The SG gave a respectable, but not steller performance, better than I expected for a wheel designed for carbon steel. The SB blackstone came in last. I can say that, in my experience, the blackstone does not perform well with heavy pressure. It glazes over and stops cutting.

Stig has told me my problem is using too much pressure. I believe him, and plan to redo the test with light pressure. In fact, I need to devote an entire sharpening session to the blackstone. I have not spent enough time working with it to really get to know it. In addition to learning about the effects of lighter pressure, I need to spend enough time using the stone grader with it to really know its effect on the stone.

I think you are slightly misinterpreting Steve. For his working set up, he does prefer the blackstone, for its longevity and speed. In the past, he used the SG enough to wear out at least eight wheels, which he uses as tent weights! His teaching Tormek set up in his shop, uses the SG. I do not know his thoughts on using the stone grader with the blackstone graded fine. I do know that he felt that using the stone grader was too time consuming for the high volume of knives and scissors he had to complete in a short time period. If Steve had been working in a slower work environment, I don't know if he would have added the extra equipment (and cost).

At this point, I must say that there are several questions that I can not answer regarding the blackstone. I can say that it does not work with high pressure. I hope other users will post. I begin with the premise that I do not believe Tormek would sell a product that they had not extensively tested and found to work. I have faith in Tormek. I have also read too many frustrated posts which have mirrored my poor results with the blackstone. Tormek needs a better product education with the blackstone. A well done five minute video on the website devoted to using the blackstone would solve many problems.

Ken

I think I heard enough opinions and facts. So then, I have to test the Blackstone myself.

Thank you for your comment, Ken.

[Ken S]

Sharpco,

I have learned a lot from other forum members and online research, as well as books. That said, sometimes there is no substitute for actual hands on work. Knowledge earned from your own work runs deep.

Please keep us posted. There is much to learn about the blackstone.

Enjoy the journey.

Ken

[kwakster]

Try using your SB-250 stone with some Blue Wonder detergent in the water basin (but don't use too much of it as then foam will start to build up)
From what i have found it will prevent the stone from clogging/glazing much better & longer than using only water.