CBN for Tormek

Discussion in 'Woodturning Discussion Forum' started by Bill Boehme, Sep 14, 2017.

  1. Bill Boehme

    Bill Boehme Administrator Staff Member

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    The grinding wheel on my Tormek is wearing down close to the minimum diameter and instead of getting a new standard grinding wheel I was considering the idea of getting a CBN wheel. The thing that had been preventing me from going ahead was that the available grits in a 10" wheel would mean settling for an edge that wasn't much better than what I could get by putting a CBN wheel on my dry grinder.

    I was aware of the new higher grit CBN wheels that Woodturners Wonders had so while at SWAT last month I stopped by their booth and talked to Ken Rizza. He recommended the 600 grit wheel and invited me to see what I thought about the grind using a Tormek-like set up that he had in the booth. To me the results looked a lot like results on the Tormek wheel ... after roughing it up with the coarse side of the stone grader ... not what I wanted.

    I told Ken that I wanted to run the wheel in water, but he recommended against doing that. I'll probably do it anyway since I don't like the nuisance of cleaning up the metal dust on my work bench. I understand the concern of corrosion due to dissimilar metals in contact so it will be important to not leave the wheel sitting in water when not in use.

    I was leaning towards the 1200 grit wheel, but after more discussion decided to go with a 1000 grit wheel. After getting home I found that getting the old stone off was going to be a challenge. Even though I had updated it with a stainless steel shaft, there was a lot of rust that had frozen the wheel to the shaft. I finally was able to remove the wheel from the shaft after removing them together and using Vice Grips and a dead blow hammer along with a generous soaking of Aero Kroil, WD-40, and whatever else I thought might work. After cleaning up the shaft I saw a lot of pitting which seemed surprising for a shaft that was supposed to be stainless steel.

    I ordered a new shaft and bushings, but my progress is temporarily stalled due to back surgery. After I get back up to speed, I'll resume my evaluation.

    I have heard other turners say that the Tormek is too slow. As a hobby turner I turn at a leisurely pace, but even so, I don't see much difference in sharpening time between using a dry grinder and the Tormek other than the time it takes to sharpen a skew chisel. Anyway, I found this short Glenn Lucas video showing how slow the Tormek is when sharpening a bowl gouge: https://www.instagram.com/p/BNeh0SjBihY/
     
  2. odie

    odie

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    Well, I believe you, Bill......and, the short video from Glen Lucas was appropriate. I don't have a Tormek, but since I do all my honing by hand, I can relate to the hypothesis of it being quick. In both cases, we're basically discussing truing up an edge that's been previously ground, but needs the very tip of the edge re-sharpened. It's quick, if it's done precisely......and THAT point is what it seems many turners are not comprehending. :(

    -----odie-----
     
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  3. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Some people like a more sawtooth like edge but I feel like that limits the final surface quality. Sometimes surface quality isn't as important when surface texturing will be done later. It's hard to make quantitative comparisons, but I believe that a smooth honed edge cuts longer than one that isn't.

    I have sharpened tools on a dry grinder with CBN wheels and am impressed by the edge quality compared to sharpening with a matrix wheel.

    I'm a little apprehensive about the results that I'll get with the CBN wheel. Even though it is 1000 grit, the surface feels rather rough compared to the standard Tormek wheel. I've heard Reed and others say that there is a break-in period for CBN wheels so I'm hoping that is true. Who knows, I may eventually decide to go back to using a Tormek stone.
     
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  4. odie

    odie

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    When you do do this, Bill.......I'm interested in hearing your findings. What are you planning to do with the upper surface of the flute on gouges?......you can't use the CBN wheel there. As you know, I've been using a round diamond hone there, and have been very happy with the results I've been having with it. If it weren't for the expense involved, I'd love to experiment with a 1000gt very slow dry wheel, in conjunction with hand honing the upper surface........:)

    -----odie-----

    edit: Agree fully that a fine edge is much more effective in producing a higher surface quality than the "sawtooth" that some turners seem to favor. The only advantage I see with it, is it's quicker to grind, without any further maintenance, and then return to your work. (.....but it's not necessarily quicker to true up an edge when the setup is in tune with that purpose, and done correctly.)

    --o--
     
    Last edited: Sep 14, 2017
  5. john lucas

    john lucas

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    Bill I find that my CBN 180 cuts just as fast as my 120 grit Aluminum oxide wheel or probably faster. I will go out in the shop in few minutes and grind a tool on it. Then I will go to my belt sander and find out what grit on the belt seems to match the quality of the CBN. That should be interesting. My on personal opinion, a well sharpened edge cuts cleaner and faster than a saw tooth edge. Now in all fairness I'm not roughing out a hundred bowls a week but it seems to work for Glen Lucas. I have been seriously thinking about changing my Tormek to the 1000 grit CBN. I never use the courser grit on the Tormek. I use the grading stone to sort of clean the wheel but not to purposely down grade the grit.
    As far as quick sharpening. If you don't let it get dull it doesn't take any longer to sharpen on my Tormek than it does my grinder unless I need to take a lot of metal off. Ideally I don't let my tools get that dull. The only thing that takes time right now is to fill the water each morning and empty it at night. That is why I'm looking at the CBN. No water. You get very little dust when you are just cleaning up the edge on 1000 grit.
    I would buy one sooner but I need new tires for the van and my 6 month insurance payment will be due shortly.
     
  6. robo hippy

    robo hippy

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    I wouldn't run it in water. If dust is your concern, some thing I have been doing lately to try to combat that is to put some Trend lapping fluid on the bevel before I sharpen. This does keep the dust down at least a little, and keeps the wheel cleaner. My main problem with loading up on the wheel is from turning sloppy wet wood and a bunch of gunk gets on the wheel. The lapping fluid keeps the loading to a minimum, which really isn't much of a problem, probably just looks better...

    The only concern I have with the really fine grit wheels is loading. Dave Schweitzer at D Way, and the Cutter Master/ Toycen or what ever up in Canada both expressed concerns about any thing over 600 grit tends to load up even if you are sharpening hardened metals on them. My first impression of the 600 grit wheel was exactly that, even before I heard it 'could' be a problem. With my 600 grit wheel, I continually make sure to put the lapping fluid on all bevels before I sharpen. In my latest sharpening video, I show where I take the Trend bottle, pop off the tilt/pop up lid off, double over a pipe cleaner leaving a finger ring in the middle and twist the ends together. This fits into the hole easily and gives just the right amount of fluid on the tool.

    robo hippy
     
  7. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I have an Alan Lacer diamond slipstone that is supposed to have a grit of 600 although after several years of use it feels more like 1000 grit. The radius on one edge very closely matches the flute of ⅝" bowl gouges and the small radius on the other edge is good for honing the flute of ⅜" bowl gouges.
     
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  8. john lucas

    john lucas

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    Bill I ran a test today. I sharpened a gouge on my 180 grit CBN and then tried several sanding belts. The grind looks very much like the grind I get from a new 180 grit belt. I have a worn 220 belt that definitely gives a finer finish. A new 320 grit belt cut faster but gave a finish appearance of my worn 220 grit belt. I remember when I took a class with Frank Sudol he used a 400 grit belt that he said was worn and cut like a 600. I was not good at sharpening in those days and had one heck of a time getting an edge on that "600" grit belt. I then sharpened one half of my spindle roughing gouge on the Tormek wheel. It's supposed to be 1000 grit but the finish still has lines and doesn't look all that much finer than the 320 grit belt gave me. Could be because I haven't used my grading stone lately. I've wondered if you wear away the finer grits with repeated sharpening and get a cut that is courser. Maybe if I remember tomorrow I'll grade it and try again.
     
  9. RichColvin

    RichColvin

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    Bill,

    There is a great review of CBN wheels on the Tormek forum. Here's the link :

    https://www.tormek.com/forum/index.php?topic=3252.0

    If you stay with the stone, I recommend the SB grindstone over the SG. The SB is much better with HSS, and I use mine often.

    Kind regards,
    Rich
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Just the opposite. The stone will get smoother and grind like 1000 grit.

    Thanks, I followed the evaluation of CBN wheels on the Tormek forum, but they were using coarser grit CBN steel wheels from D-Way. There's another thread where one of the members evaluated a higher grit (350 grit I think). Thanks for the recommendation on the blackstone wheel. I had been considering it for a number of years.
     
  11. Zach LaPerriere

    Zach LaPerriere

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    Now this conversation is getting really interesting! I agree that a fine edge cuts much cleaner than a sawtooth edge.

    Over the last couple of years I've gone for the two extremes in sharpening...I do all my roughing with a 60 grit CBN wheel (it was 80 until fairly recently, but the 60 is a bit faster for shaping the secondary non-rubbing bevel) and all of my finish work is sharpened at 800.

    Robo is right that the finer grits load up. I'm not a production turner, around 150 bowls a year, and the 800 grit is holding in there after a year—though it's about time to soak and clean again. Previously I sharpened for a year or so at 1000 with one of Ken's wheels, though I switched to Dave's 800 wheel after the 1000 seemed to be staying a little loaded. It's possible I just didn't clean the 1000 well enough. I've never used a lapping oil, though it seems prudent.

    Because I use on Michaelsen grind, I only ever sharpen around a 1/16" of bevel with the finer grits, so the gouge only gets a light pass on the 800. I could see where a full bevel at higher grits would load fairly fast.

    I'd really like to see more research and/or compare notes on getting wheel unloaded. Dave suggested soaking then scrubbing with a strong soap that would break down the wood resins that might be causing some of the loading.
     
  12. john lucas

    john lucas

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    We need to lump this in with the CBN wheel cleaning post that just came up. Very interesting.
     
  13. Mike Johnson

    Mike Johnson

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    Novozymes produces a large number of enzymes used in every industrial, commercial and retail product
    on the market today. They produce custom engineered enzymes that will break down just about any
    material needing to be cleaned from a surface. Dish detergents have small amounts of specific enzymes
    used for the task, they make a number of concentrated products that are used in other industries that may
    speed up the process for cleaning grinding wheels.
     
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  14. robo hippy

    robo hippy

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    My fine wheels 'appear' to have some loading, but they still cut fine. More experimenting needed.

    I guess one interesting thing for me is that my 6+ year old 180 grit wheel leaves a very polished surface, especially when compared to a new 180 grit wheel, though I really don't notice a difference in how they cut...

    robo hippy
     
  15. Zach LaPerriere

    Zach LaPerriere

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    I thought to share an experiment that probably doesn't need repeating! Regarding the difference in burrs created by a CBN wheel, I thought I'd try sharpening with the wheel going in reverse. So I sharpened a handful of 1/2 and 3/8" gouges on the backside of the grinder, which of course means that the wheel was spinning up, rather than down and toward the cutting edge.

    The sharpening created a burr that at the end was long and could be broken off when I looked up close. Under a 20 power microscope the edges looked similar once this burr had been broken off.

    When cutting wood I found that the reverse ground tool appeared to be as sharp as the normal grind for the first half inch or so of cutting then the edge went to pot. I went through a dozen or so reverse sharpening before I completely gave up.

    EDIT: I only tried with 800 grit, so this could skew the results, and I only tried with one a fingernail grind somewhere around 50 degrees.
     
    Last edited: Sep 17, 2017
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  16. robo hippy

    robo hippy

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    Interesting Zach.... I know Jimmy Clewes prefers a reverse/up side down sharpened scraper burr for his clean up cuts. I would think that the burr would fall off quickly than the tool would cut as normal rather than be more blunt...

    robo hippy
     
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  17. john lucas

    john lucas

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    Interesting Zach. I have a belt sander and have been playing with sharpening on it to see what the advantages and disadvantages are. I have the belt running up so essentially in reverse. I don't notice a bit of difference in how the edge holds up. What I have notices is that when I use the 320 belt instead of 180 it holds an edge longer. On my bowl gouges not so noticeable but on my spindle roughing gouge on dry wood it's noticeably longer.
     
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  18. Zach LaPerriere

    Zach LaPerriere

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    @robo hippy @john lucas I forgot to mention that my little experiment was on my 800 grit wheel.

    The results surprised me, too. But on the other hand, when sharpening knives, everyone I know suggests either sharpening in circles or sharpening toward the edge, especially at the higher grits.

    Why the edge failed on the gouge so fast defies any explanation I can come up with.

    John, that's pretty interesting that the 320 belt hold an edge longer than 180. I can't say for certain, but I'll echo what Robo and others have said that a finer grit CBN edge doesn't last as long as a courser grit. There's just so much to learn.
     
  19. Raul McCai

    Raul McCai

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    Stainless steel is not what it's cracked up to be. Leaving aside the dozens of grades of stainless some magnetic - some not, Some weldable - some not, some can be heat treated - some not. Different SST tolerates different kinds of acids - yadda yadda yadda. One thing is a constant. Stainless Steel is only Stainless because of the Chrome Oxide layer on the surface that results from Chromium migrating (yah - swimming like a fish through the metal) to the surface and interacting with the O2 in the air. Then it becomes Chrome Oxide. When it's underwater in an Oxygen deprived solution the Passive Oxide layer can become depleted and corrosion can set in. That's why one doesn't use SST screws for boat-building. Low O2 in a bay or estuary will cause the SST to rust. Now Inconel is altogether different. But no one sells shafting in Inconel.

    All that said. I've always wondered something about CBN wheels:
    How Long do they last?
     
  20. terry q

    terry q

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    I bought the 10" Grizzly wet grinder took the wheel off and replaced my Tormek stone. I then put a 600 CBN on the Griz. The Griz turns a little faster than the Tormek. Grizzly stone is 1200 grit.
     

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