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Have you measured the edge angle on it?  From what I've seen from Ontario in the past it would not surprise me were the edge angle on the order of 30 Degrees Per Side.  This is about twice as obtuse as it really needs to be in order to have a relatively durable edge for wood cutting.  I'd bring that down to at least 17 DPS, personally.

Hi Rich.  It would free up both hands to position the blade flat before starting the wheel lowering the risk of error in engaging the face to the wheel.

I might be wrong, but it seems to me like a very bad idea: the still wheel with no water running over it has a much higher friction coefficient than when it's already running. So there is a much higher risk for the blade to catch, messing up the blade and potentially injuring you.

I agree completely, seems like an unnecessary risk.

Can you try rotating the diamond cutter so a different part of it is exposed and doing the cutting?

For the shaft, can you use a micrometer and check the runout where the bushings contact it?

I would do both but I do not have a micrometer or even understand what you mean to check runout.  Another thought was that the washer which is just behind the large plastic hand tightened nut that snugs the honing wheel may have been loose.  I will tighten this and see if it matters.

I would try turning the diamond tip but do not have a metric wrench set and it doesn't fit any SAE allen wrenchs that I have so I assume metric.  The recommendation to replace the tip sounds strange because I can see plenty of visible diamonds and they are cutting.  The problem is the inconsistency of depth of cut.

I have run into an issue with this that is constant and cannot seem to overcome it.  I have a newer T8 machine that I have used somewhat heavily, I've gone through almost half the life of the SG-250 stone.  I have trued often with the TT-50 but now I cannot get a flat surface and have also ran into issues of the surface being cupped horizontally AND the surface on the outer side of the stone begins to chatter and cut chatter marks into the stone that look similar to an all terrain tire tread but they are very shallow.  I've tried coming from both sides of the wheel with the TT-50. 

A call to Customer Support lead me to believe I need a new TT-50 exchange tip but I don't believe this is what is causing it.  I noticed the tip has a slight tilt where it is not sitting perfectly level on the stone surface because I've always trued from the outside to inside of wheel.  The CS person told me that I should always go both ways and that this likely caused the tip to go out of flat.  I don't see why this would matter.  I also suspect I may have a problem with the nylon bearing/bushings as I went far longer than I should have without cleaning and regreasing the main shaft.

Anybody care to weigh in before I go play whack a mole with changing components and hoping it helps?

The SVM jig is much better if you want to pivot a knife with a big belly, assuming you have some kind of after market pivot add-on.  This could be addressed in an updated KJ-45 with an adjustable stop, which I would really love to see.

What is this pivot you speak of? 

I generally get around having to pivot blades just by clamping the jig further towards the handle or right at the handle and also angling the jig to match the curvature.  This way I generally get nice even bevel width just about all the way to tip in almost all cases.  Some really heavy bellies on short 4" under blades can be a real challenge though to get it clamped the ideal way.

I do professional sharpening and having both is a must, there's been plenty of knives coming my way that don't fit within the constraints of the KJ-45.  Chopping knives are thick and when they are full flat grind it is not compatible, which IMO is one of the biggest reasons to own a grinder like this in a home environment is reworking heavy/thick tools that would be a major work on stones.

I have been trying to sharpen a friend's Kershaw 1830 with 8Cr13MoV steel.
I have sharpening for several years with pretty good success (sub100 BESS as a consistent goal).
This knife is making me crazy.
I have set a 15deg bevel(30deg included) on a T8 with a CBN80.
I have been trying to raise a burr with a CBN160 wet,edge leading, and cannot.
I have reverted to the SG 250 (coarse) - to no avail.
Any advise would be a appreciated

Advice : DO NOT ever set out with the goal being raising a burr.  I know this is common dogma in sharpening, first raise a burr then remove.  I get it, I try to avoid forming a burr.  Get the apex thin to where it's slicing newsprint and then switch to the finishing stone or leather wheel and make a few light passes.  Drink a beer and celebrate life.  No burr necessary.

Unless I'm missing something I don't think it's possible to thin knives on the top of a Tormek grinding wheel : you would hollow grind it and would not be able to grind at a low enough angle if the knife is in a jig. The jig would bite into the stone.
Theoretically you could use the side of a diamond or CBN wheel but I think it would be extremely difficult, either free hand or using the MB 100(?), this would require a knife jig to hold the knife and it would still catch on the stone.
Someone else may be more enlightened than me and suggest a way to do it.
I just can't see how a Tormek can be used to thin knives.
Once I tried to flat grind a scandi knife on the side of a diamond wheel free hand. It was a disaster!

Actually this is exactly how many Japanese forged kitchen knives are shaped after forging but they generally use a larger radius wheel than the Tormek which will further reduce the hollow grinding.  I have done it and it works but take care to avoid the apex of you will take out big pieces.  Also rocking the blade a bit will effectively grind flat although there will be some inevitable high and low spots.  This can be cleaned up on 220 grit waterstones if needed to give perfect flat or convex.

You do get some of the "benefits" of a convex, for example a soft shoulder, bit of a convex shape, etc.  Of course there'll be some "defects" I said that before too... like you said a bit wavy, etc.

But then is it not better to just thin the knife by lowering the support bar one or two full turns before sharpening, get close enough to the edge and then sharpen at the desired bevel angle height ? That will soften the shoulders, result in a convexish shape, and be much faster and more consistent ?

This is a nice idea but it's liable to have the same tendency to inaccuracies on a different level.  I think if you really care about high precision then it's best to use bench stones to finish.  I've not found a way to rival the precision I can get cleaning up bevels by hand on stones.  When I did KJ-45 convex for a few knives I always finished on stones to get a nice shaped convex. 

So maybe there are weird things going on with your camera, but...

On pics 707 and 708, there are visible indents on the edge and on the black coating (I circled them in red). If they're visible on a low-res pic, they probably are quite obvious irl, and I think polishing would only increase the contrast.

I'd wager they come from the not-so-controlled up-down movement. The fact that it has to be there at all makes it extremely hard to have a smooth movement along the length of the edge. I'm sure you could get rid of those with a lot of practice, but still... If the process introduces an intrinsic weakness, maybe the tooling isn't adequate.

I have seen pixelation in photos uploaded to share online before which look exactly like those dips.  I don't believe the KJ-45 could make hard dips like that, it would likely be more liked rounded holes in the edge similar to half moons.

I have used the convex method with the KJ-45 and while your concerns are well warranted I do believe it's something that can be overcome with proper technique for the most part.  I certainly did not have that issue which the photo suggested.  What I did have was less than ideal blending in a few spots.

Based on what you're saying, a DF wheel should be more of a burden than a blessing (mandatory use of ACC, at least a DE wheel in addition, and still the SJ if you want to polish.

Also some spoon carving knives, but i guess those can't be sharpened with the Tormek.

You might want to look at this video with Wolfgang. I have never sharpened such a tool, and it might require a lot of practice. Wolfgang has a tendency to make complex things look easy thanks to his level of mastery and feeling. The SVM-00 in itself requires quite a bit of experience and training, so ...

Thank you so much for posting this link, I've never seen it. Looks possible but certainly not easy to me!
As for the wheel, I'm almost certain I'll get the normal version of the T-8, just seems more suited to my needs.

I would argue that it's perfectly suited to what you intend to sharpen with it.  Your results will come far more from your skill and understanding of sharpening fundamentals than what you are using for wheels. 

If you are mainly sharpening carving tools then I would definitely agree that a 4000 grit wheel is going to serve you best as a finishing step.  There is no need for diamond wheel considering your tools.

If your main interest was buying the T-8 Black because of the 50 year warranty, well I'd say that's not going to be a factor for most people at all.  If you're a professional sharpener then may be a big deal.

If you are really set on getting a refined edge along the lines of the 4000 wheel, then adding a stone like the Sun Tiger 800 after the SG-250 would be highly recommended as an intermediate step.  The 4000 cuts very slowly and loads very quickly so does not grind quickly.  As others have mentioned you can simply grade the SG-250 on the fine side of the stone grader to get a similar finish on the edge to help make the jump to 4000 wheel. 

Otherwise you'll be at it a long time trying to remove deep scratches from the SG-250.  If you don't mind having scratches mixed in the surface with the polish then you don't technically need any stone between but this would serve to remove the scratches only prior to 4000.  If you are only interested in actually polishing the apex and do not care about looks, then jumping to the 4000 wheel using micro-bevel is best.

Also, Sun Tiger does offer 4000 grit stone as well but it's not a direct replacement for the Tormek 4000 from what I can tell.  It is in fact much cheaper but that may or may not mean it is of lower quality as it does come from a well respected Japanese stone manufacturer (Matsunaga) which produces the King Deluxe line of stones which are just about the industry standard for Japanese waterstones.

One thing that hasn't been mentioned which is worth noting is the difference in how plated abrasives like the Diamond wheels cut compared to bonded abrasives in the stone wheels.  There is a single layer of diamond plating which means they will cut far more coarse than a wheel of the same grit that is produced as a traditional stone that is bonded like the SG-250.  They are also MUCH easier to damage with errors of too much pressure, angle, etc.

In short, the type of minutia we are discussing only becomes relevant when you are chasing an ideal edge.

Pretty much. Sure edge retention - again it depends. Some blades such as scissors and to a certain extend vegetable knives require a level of tooth to function as intended. Whilst other edges such as on a scrub plane can be left at coarse and function perfectly well. (Scrub planes are all brute force and ignorance and the say in the classics.)

In the case of say paring chisels you want a nice keen edge and that warrants more attention to detail and so you would probably spend more time chasing a better edge.

So yes it all depends. I am a hobbyist but I end up sharpening for friends and family as well. But for me it is the speed and function of the system. I don't see sharpening as an end in itself. For me it is in order to get more pleasure  out of the making functional objects or producing functional tools rather than the actual process of sharpening. It is almost amusing to see how slowly the stone can cut when it is used with light contact pressures and not resurfaced properly once you recut the surface for comparison.

Certainly, edge retention is important but if I spend an extra 15 minutes per tool only to get an extra 5 minutes of use there is not much point. So for me it is a trade off and it boils down to a time/result equation. Getting back to the original question, this is where the science cones in. It will inform my approach to sharpening to get the the most out of my sharpening system with as little expenditure as practical.

This is not to decry those for whom the experience of sharpening is an end in itself. I see the joy in refining an edge to get the lowest BESS score and the prettiest edge. However my needs are more pragmatic.

If time is an important metric then using loaded/glazed stones is never advised.  I recut my wheel far more than most people would likely that use the machine, using the truing tool, because time is extremely important to me.  Using the truing tool makes recutting the surface makes the grinding action enormously more effective at removing metal quickly and that is most of the reason for even using a grinder compared to a benchstone. 

One thing I have discovered over my life is that sharpening is simple yet complicated. Sometimes over complicated. If you want sharp all you need is two flat surfaces meeting at a line. However, when you throw in grit, abrasives, the behaviour of your sharpening grains, the behaviour of the material being sharpened, the geometry of the edge it can escalate quickly.

My observation is that we can overcomplicate and overthink. Sure the science is interesting and can feed into practice to improve our technique but when you look at professional sharpeners such as knife sharpening businesses or professional woodworkers they want in and out in the quickest time whilst getting good results.

Example. I bought a jointer plane Wednesday and the iron was non too smart. The edge was chipped and the bevel was not a bevel. It took me 15 minutes for a perfect edge. Ten minutes on the DC to re-establish the bevel, 30 seconds on the DF to remove the old scratches then 30 seconds on the DE to polish. Finally about 30 seconds to a minute to hone to remove the burr. It then took perfect shavings. It will take less than 5 minutes to re-sharpen and that I think is the point. I use the Tormek (and I have wanted one for a long time) to quickly re-establish sharp without any faffing around. I now have that. It took some time to establish my process and I am yet to become as confortable with the drill jig and the turning tool kit (I need more practice there) but chisels plane blades an knives are now a cinch, super easy, barely an inconvenience.

In short, the type of minutia we are discussing only becomes relevant when you are chasing an ideal edge.  If you're happy with good enough then this is simply not relevant to your interests.  Many have very low expectations of edge retention and don't even know how the sharpening process weighs heavily in that end point.  For 99 out of 100, good enough is MORE than good enough. 

Hello,
this is my first post here, glad i found this forum.
I want to buy a T-8 and think about getting the black 50th anniversary edition with the df-250 diamond wheel. I do realize that the standard SG-250 is a more versatile stone, but I'm still tempted by the 50 year warranty, the composite honing wheel and the diamond stone in the black edition.
My question is:
if I want a really refined surface on my tools and knives, would i need to get a DE-250 as a follow up to the DF, or could i directly go from DF-250 to the SJ-250, which is around 4000grit?
Any input would be much appreciated.
Cheers-Simon

If you're new to the Tormek I would suggest starting on the SG-250 as it will be much more forgiving of mistakes which are inevitable and actually it's a great stone to work on for most common steels.  The downside is you'll have to a true it often to recut the surface to keep it cutting aggressively and flat/precise surface.

Follow up stone all depends on what you are sharpening and what you are using that tool for exactly.  Even just saying it will sharpen knives means little as you can do different types of cutting, etc.  Using a 4000 grit stone after the diamond stone could either increase or decrease actual performance.  If you're primarily push cutting (no slicing motion or draw but cut like a chisel) then you'll be best served with 4K.