Replacing SB 250. To sparkle or not to sparkle? That is the question.

[Rob]

Morning Folks (well it is in England anyway).

Despite the title, this is a serious question.

My trusty black friend, the SB250 has finally run out of diameter and has reached the stage where I have to remove the honing wheel for anything long.  I've just had a frenzy of knife sharpening and that was the final nail in the proverbial coffin.  it's still OK for gouges for turning because they're largely ground from up above in the elliptical jig and dont foul on the honing wheel.  But as for anything else, particularly chefs knives, alas, too small.  I think it was down to about 190 from memory so really has served me well and I think I bought it in 2015 so its pushing 5 years.

So I've done a round robin to see whats new because I have been a little distracted of late and not been on the tools anywhere near as much as I would have liked.  All comes of that pesky distraction - having to work for a living.  Boo.  Hiss.

Whats popped out of my research is of course the advent of the "girls best friend" diamonds!  They weren't really a thing last time I looked, now it seems, they really are.

Now I dont take the replacement of my SB250 lightly because it's been a versatile friend, primarily to my wood turning which has become the dominant form of my woodworking but also to the outlying fray of other edge tools I have need to sharpen.  That includes all the usual suspects ie scissors, kitchen knives, plane irons and chisels and the odd set of secateurs (felco of course).  So the replacement has to be every bit as "game" as it's redundant original.

They're also, a fair sized investment for a consumable so the value must be there.

I could of course simply replace the SB with another but that would be to betray the opportunity that innovation brings and that doesn't sit well with me.

So, I dont have the knowledge to make this decision on my own.  I thought, who/where should I turn to for expert advice and guidance and of course, add to that, warmth, friendship and camaraderie.....and of course......I visited my local tool shop!   No....stop it.....I came here.  Didn't give it a seconds thought.  I knew you guys would know the answer.

What I haven't done is trawl through umpteen posts on here to "mine" the answer and for that I apologise.  But perhaps a good enough starting point to engage your very useful minds is to say that my current thinking is to opt for the 1200 grit very fine diamond wheel.  My understanding is it's never going to need dressing (so that's one in the eye for the SB....no more need to worry about gouges furrowing the stone, requiring endless redressing with the truing tool).  Allied to the last, it will never lose it's shape and therefore will remain geometrically accurate to the universal tool rest?

Those seem to me to be the fundamental differences between this medium and a friable one like the grey or black stones.  in short, it never changes shape through the action of grinding.  Is this absolutely 100% true for HSS turning gouges with, swept back wings and quite pointy tips like 3/8" bowl gouges?  I ask this because those suckers really really really do grind quite the trench in the SB over a relatively short space of time.  So not just the diamonds themselves (which I appreciate are about the hardest substance known to man) but the underlying wheel itself would have to phenomenally resistant to avoid this happening in the future.  Are we certain this is the case?  Do we have precedent from any wood turners that use HSS gouges in the elliptical grinding jig?  This is definitely my greatest concern because I guess once, it's dented in any way, it's more or less useless since you cant dress or true it.

The other can be packaged in the general versatility category i.e. I do need this to perform widely once we're beyond high speed steel turning tools.  So my next priority would be the global knives in my kitchen.  I'm a reasonably accomplished chef and not only cook for my family on a daily basis but have wont to throw the odd dinner party where I will prepare more esoteric dishes of the moment.  This is a chore if the knives are blunt and a joy if sharp.  So this application is also really important.  Add to that the usual cornucopia of other assorted tools including scissors and my needs are met.

The grit question is the next big one then.  9 times out of 10 I'll be coming to the Tormek with a known edge and therefore only require sharpening, not shaping.  Is my thinking correct on this........the friable stones, when graded with the fine side of the stone grader, end up at 1000 grit right?  The finest diamond stone is 1200 grit?  So by buying the 1200 grit, I'm more or less just polishing the existing bevel?

The fundamental question for me, with respect to grit size is......will the 1200 be just a bit too fine and leave me grinding for ages if I dont set the angle accurately enough?  is it forgiving enough to remove enough metal to still give an edge if I'm out by a degree or three? 

I'm not big on fiddling and messing so I dont want to waste my life having to be uber careful setting the jigs all the time.  On the other hand, I dont want a medium so course that the edge isn't fine enough.  it's this balance between setup time and edge quality that's got me agonising between the 600 and the 1200 grit diamond stone choices.  I'm pretty clear I dont want the course one though as that seems to be more in the "ding removal" camp.

So that's my dilemma folks, that's what I would humbly ask that you bring your excellent minds to bear on and help me make the decision.  it boils down to this I think:

Should I replace the SB 250 with an SB250 or the 600 or the 1200 grit diamond stone?  But more importantly, why?

Your input, as always, is appreciated.

All the best
Rob

[Ken S]

Rob,

You ask excellent questions. (I would expect nothing else from you.) Unfortunately, Tormek, my primary source, has not released much information. Tormek had experts doing year long testing before the diamond wheels were released.I don't know how many testers were involved, only that Glenn Lucas and Nick Agar were part of the group.

I am convinced that Tormek has gathered a lot of knowledge about these wheels. I do not know why this knowledge has not been disseminated among users and potential buyers.

From my limited experience with the diamond wheels:

Diamond cuts differently than "the traditional wheels". It's not just about grit size. Diamond wheels just keep cutting. I found that although the DC coarse wheel was not a speedster, it gave me good feedback that it was cutting and did not slow down. I was reshaping a skew to Lacer grind. The DC did the heavy grinding. Next up was the DF and finally the DE. All three were noticeably different. With that in mind, coupled with what Glenn Lucas, a production bowl turner, writing bout using the DE in his blog, I think the DE-250 would serve you well for maintaining the sharpness of your tools which were already shaped as you wanted them.

Tormek, to its credit, makes no "diamonds are forever" claims. Looking at wheel prices, if a diamond wheel lasts twice as long as a traditional wheel, you are money ahead. I have no doubt that, if used carefully with ACC solution and light pressure, diamond wheels will prove cost effective. I think you might eventually want a second grit.

If you ever decide to Brexit and move to the formerly colonies, I would gladly lend you mine for a good trial.

Keep us posted; I value your thoughts.

Ken

[Rob]

Many thanks Ken.

I might have a gander at Glenn's BLOG actually.  Like you I really rate him so his input will be worth reading especially considering he was an official prototype tester for Tormek.  I might even drop him an e mail as I have an account with him.

But your recommendation of the finest of the three sounds reasonable too.  I appreciate your input, many thanks :-)

Best
Rob

[Rob]

Right....I've gone and bought another SB today.

I guess on balance I wasn't inclined to accept the risk of the diamond stone given it was nearly a hundred bucks more and as we're all agreed, scant detailed information about it's performance and longevity.  it seemed a bit too much of a shot in the dark.

So I've opted for known security and safety over blind innovative optimism :-)

[Ken S]

Rob,
Your reasoning is perfectly understandable. Your SB has worn down because it has worked for you. Actual past service is a valuable indicator.
Keep us posted!
Ken

[RichColvin]

Rob,

I replaced my SB-250 with another one.  I looked at the diamond wheels, and here's what I determined:  https://forum.tormek.com/index.php?topic=3805.0

But, I must add that I'm thinking about moving to the new Turner's Edge gouges from Robust.  And, if this is indeed the case :

To make Turner's Edge gouges, we start with premium high-speed steel (M2).  After machining, the tools are heat treated to 64 Rockwell C.  The hardened tools then go through the Nitriding process, increasing cutting edge hardness to 1880 Vickers (75+ Rockwell C).
  - http://www.turnrobust.com/product/turners-edge/

I may have to move to diamond wheels to sharpen those tools.  That is a pretty hard steel!

Kind regards,
Rich

[Jan]

Rich, you are correct. The M2 steel contains some 6% of tungsten and some 2% of vanadium. Both the tungsten and vanadium carbides are as hard as or even harder than the silicon carbide abrasive in the SB stone. The diamond wheel will cut the both mentioned carbides without any difficulties.

Jan

[Rob]

Those gouges do sound awesome but I simply dont put enough hours in at the lathe to warrant moving away from HSS.  I suspect my current crop of gouges will outlive me so other priorities will doubtless claim my disposable income first :-)

[RichColvin]

Rob,

I'd love to get feedback on them.

Kind regards
Rich

[Rob]

Rob,

I replaced my SB-250 with another one.  I looked at the diamond wheels, and here's what I determined:  https://forum.tormek.com/index.php?topic=3805.0

But, I must add that I'm thinking about moving to the new Turner's Edge gouges from Robust.  And, if this is indeed the case :

To make Turner's Edge gouges, we start with premium high-speed steel (M2).  After machining, the tools are heat treated to 64 Rockwell C.  The hardened tools then go through the Nitriding process, increasing cutting edge hardness to 1880 Vickers (75+ Rockwell C).
  - http://www.turnrobust.com/product/turners-edge/

I may have to move to diamond wheels to sharpen those tools.  That is a pretty hard steel!

Kind regards,
Rich

Very interesting.  I didn't actually read that thread before I made my decision but I guess I've pretty much arrived at the same conclusion with a lot less research :-)  My only use of Tungsten category hardness is for very small bits that attach to deep hollowing tools and I sharpen those on a linisher style sharpening system which works really well.  I also haven't explored the Norton wheels at all and my guess is they would be a lot less pricey.  I've upgraded to a CBN wheel on an Oregon compound angle chainsaw sharpener I bought last year because the turning club I'm with often harvest our own wood.  Whats really nice is not having to dress and not having to adjust because wheels dont change shape.  On balance, I also shape with the linisher as I long ago recognised the Tormek's real forte is in sharpening not shaping.  Feeds n speeds springs to mind!  So I guess the reality is I just have no pressing need for diamond on either a shaping level or M2 or carbide level.  But you never know.....I might :-)

[Ken S]

Rob,

For the many years that I worked in my home photo darkroom, I wrestled with whether or not I should gear up to be able to make 16x20" prints. Surprisingly, logic carried the day and I never made the investment in bigger prints. The business side would never have supported prints that large. Also, artistically, I have always preferred smaller prints, 8x10" or (usually) smaller. You set a wise example by setting up your turning tools and grinding wheels for your actual real world needs.

Such wisdom is rare in someone your age. 

Ken (aka "the old guy")

[Rob]

It's a peculiarly male trait isn't it?  We go into a "shop".  Doesn't matter if it's fishing kit or a chandlery for boating related stuff, a decent knife shop or indeed woodturning.  The fact is we of the male species seem to have a near primal urge to consume vast quantities of shiny things :-)

We (I know I do) frequently then post rationalise the purchase on some flimsy pretext that we might "grow into it over time" and have genuine need for whatever the esoteric function is :-)

It's usually either money or my wife that bring me back to reality in this flirtation with the "devil of temptation".

I made that mistake with a Harley Davidson heritage Softail Classic in 1999 and I still have her sat in my garage to this day.....with a staggering 2.6K miles on the clock!!!  (I bow my head in shame) :-)

[blackhawk]

I purchased a DF-250 (Fine) stone just a few weeks ago.  So far, I have only sharpened bowl gouges and scrapers with it.  The diamond will sharpen aggressively at first just as the instructions mention.  I am just now at the point where the diamonds have started to settle in and grind consistently.  In my opinion, the DE-250 would be way too fine.  I'm second guessing a little that maybe I should have bought the DC-250.  All the woodturners that I know using 1750rpm bench grinders use no finer than a 180 grit CBN wheel.  The main thing that I like about the diamond wheel is that glazing of the stone is eliminated.