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Tormek SG-250 results
#1
Hello Forum.....Its been a while....

When Tormek brought out their new Diamond Wheels, I got the bug again to invest my spare time into Learning, Reading, Researching how to produce Sharp and Keen Edges. 

I am still a beginner. Probably less than 200 knives/scissors under my belt. I can now comfortably take a dull knife, and make it less dull!

I want to do better. But more importantly, I want to quantify my results, so this week I hope to order my PT-50 ( A or B) ( But probably A).

I was also going to get a SJ-250...but after reading many posts here, for less money I can get a bench grinder and Paper Wheels, but feel I need to master the First Grind on my Tormek, before spending another cent ( beyond my PT50).

So here is my question:

What sort of sharpness does a skilled sharpener get right off the Tormek SG-250 and Leather wheel as supplied??? I guess I am looking for a target result to hopefully achieve in the near future...

Yes...I know it depends on the blade, so I am thinking just a commercial grade of stainless kitchen knife (RC 52-54?)

Thank you for your input in advance,

Sam
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#2
Hi Mr. Sam and welcome to the forum.
 
You ask good questions and your decision to not spend more $$$ before figuring out what’s up is wise one. Your Tormek with the standard wheel is plenty capable of producing very sharp edges.  IMHO, the SJ is only for experienced sharpeners who are looking to produce a very specific result.  I now sharpen on a Kalamazoo 1SM belt grinder, but I have a Tormek and have sharpened many blades with it.
 
I think you will be amazed at how much you can learn by getting the PT50B.  The most important thing to understand about it is that it works, is extremely accurate and can tell you a lot about what’s going on at the edge. When, and you will, see variation in sharpness readings along the edge it’s because there is still burr in some areas or the edge is not completely sharpened.  It’s an amazingly accurate instrument.  You can trust the information it provides.
 
Burr removal is far more difficult to understand and takes more practice than simply getting the edge sharp.  If your goal is a polished edge burr removal is not that difficult, but if you pine after a toothy edge like I do, burr removal requires a good understanding and some practice.  There is a lot of information about it here in postings on the Exchange.
 
Your PT50B will provide a lot of good feedback but I would also recommend you also get at least a 10X loupe or a USB microscope to examine your edges.  An edge tester and a microscope are an invaluable combination for learning about sharpening and burr removal.
 
http://bessex.com/forum/showthread.php?t...24#pid3824
 
To answer your question, with the Tormek, I would shoot for around a 150 sharpness reading.  You can get sharper but that does not necessarily mean better.  The thing to understand is that these super sharp edges are extremely thin, and that includes a 150 edge.  Anything sharper is so thin it bends (rolls) so easily that it will lose sharpness very quickly even when treated most grandmotherly during normal use.  150 is not that difficult to get with the Tormek and the standard wheel. 
 
Hope that helps, and looking FW to your results and questions.  There are a lot of experienced folks here more than willing to assist if we can.
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#3
Welcome, Sam.

Grepper's advice is very solid. Before he went over to the dark side of the force with his Kallie, he was one of the most innovative, stalwart Tormek users. We still love him, and pray continually that he will repent and return.

Enough good natured kidding. I have the orignal PT-50. I have been very satisfied with it. However, if I was starting from scratch, I would opt for the PT-50A. I have no doubt that the B would more than do everything I might need. I have a hobby interest in precision measurement. Sometimes the overkill hobbiest in me outweighs the thrifty, practical realist. I would rather drive a practical car, which will wear out, and have a top of the line tool, which will last longer than I do.

Back to the Tormek and the SG-250. For those of you who may not know, I believe "SG" refers to SuperGrind. (250 is the wheel diameter in millimeters.) The original Tormek grinding wheels were natural stone, mined from a Swedish island.
The SG stones are manmade aluminum oxide. They are faster cutting and more coarse than the original stones. I think the original use of the stone grader was to allow the SG stones to utilize their inherent faster cutting and also to be graded finer, like the natural stones.

Orthodox Tormek technique, 220 and 1000 grit from using the stone grader with the SG, ignores two other subtle controls. First, the stone grader can produce more than two grits. On a practical basis, there is also a middle grit, called “600”. This is essentially a medium grit somewhere between 220 and 1000. Related to this, I have found that using the stone grader fine side for longer than the recommended time produces a smoother finish.

The second factor is grinding pressure. At my request, Grepper, our USB microscope guru, made some edge photos showing the effect of using light grinding pressure with the final passes. I was impressed with the difference.

The third factor is using the leather honing wheel with the knife controlled by the jig and support bar. Most of us, myself included, are not really experienced enough with freehand honing to make it work well.

All of this is my sttempt to make the case that I believe very few Tormek users really get the maximum finesse with the SG-250. I use and like the new diamond wheels. They definitely cut faster. I am not convinced that they will produce sharper edges. They also transform a $600 sharpening machine into a $1500 machine. For that difference, my practical side is willing to make a few extra passes.

The SJ 4000 grit Japanese wheel will deliver bragging rights for a highly polished edge. My typical kitchen knives seem plenty sharp with a carefully used SG.

Keep posting!

Ken
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#4
Thank you Gentlemen!!!

Am I correct that a Bess Score of 150 is about out of the box factory score in many cases?.....I guess I was hoping that something better than factory was easily acheiveable.....
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#5
Sam,
Here is the official chart. BESS 150 is noticeably sharper than factory new for fine cutlery.

http://www.edgeonup.com/eou_new_2016_008.htm

Ken
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#6
I agree that BESS 150 is sharper than factory new and that it can be routinely achieved with just the SG250 stone and the leather wheel.  This last summer I did a stint as a knife sharpener at a couple small, local farmers markets.  I used the SB250 and SG250 stones and the leather wheel and was not satisfied with a knife suitable for delivery to a customer unless it was under 200 BESS.  At home where time was not an issue, I was able to routinely get edges in the 90 - 130 BESS range.  

Rick
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#7
New, out of the box knives vary wildly in sharpness.  There is absolutely no standard or expectation there.  This is true for cutlery and other types of knives as well.  I think there is some consistency with within brands/models, but other than that there is little if any consistency. 

As an example, check out this subwoofer knife review:

"The TM1's factory edge has an average BESS 'C' sharpness of 342. "
http://bessex.com/forum/showthread.php?t...46#pid4346

or this one:

"The Sliverax's factory edge has an average BESS 'C' sharpness of 186.
http://bessex.com/forum/showthread.php?t...31#pid4031


I think 150 is a good general sharpness.  The thing to understand though is that if you take a freshly sharpened 150 edge and chop some potatoes the sharpness will probably be 200 or greater.  It does not take long.  Try it yourself.  Sharpen a blade, test the sharpness and then chop some carrots and onions. Then check the sharpness again.  I think you will be surprised.  

In fact if you sharpen a blade and just let it sit overnight, it will be duller the next day... by up to 40 points!  You don't even have to cut anything.  Check this out:

http://bessex.com/forum/showthread.php?t...84#pid3684

I'm not saying that for some purposes such as gently slicing sashimi or experimenting with cell splicing that you might not wish a sharper edge.  A 100 edge glides through a kumquat and feels magical.  The only problem is that cool feeling is very ephemeral and probably not worth the extra effort for general use cutlery.  Umm... that's just IMHO.

A 100 edge, or even a 150 edge is very thin and rolls quickly.  Especially if it is a polished edge, it will soon start to ride on the skin of tomato or broccoli or onion, etc.  I think 150 is a good balance.  It's really sharp and at least has some durability.  Again, that's just my opinion and you may very well feel differently and like some other level of sharpness.  The only way to really know is to experiment.
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