CBN Grinding Wheels

[robo hippy]

I originally wrote this for Woodturning Design, but right after I submitted it, they folded. It was too long for the AAW Magazine, and I couldn't edit it down far enough for them, so I am posting it on my web site. About 4,000 words. It covers every question I have seen asked on the turning forums.

http://www.robohippy.net/featured-article/

robo hippy

 

[john lucas]

Excellent Reed. Wish it had been published. Well worth a read especially if you are thinking of buying a CBN. I certainly love mine and will probably gat another one sometime with a different grit.

 

[Terry Vaughan]

Thanks from me too, very useful. There are always more questions though. Can you say how good an edge they put on gouges and skew chisels, compared to a Tormek or a standard high speed wheel?

Also, I have some tipped tools with HSS brazed onto mild steel. I take it that the brazing metal and mild steel would not be good for a CBN wheel, or at least the loaded metal particles coming down on the edge would prevent the HSS from sharpening well?

Terry

 

[robo hippy]

Terry, I can't really compare to the Tormek and clones or standard wheels as it has been so long since I have used them. For sure, the edge comes out way more polished, especially once the wheel gets broken in. I would say the edge is finer than what you can get from standard wheels. The Tormek, is pretty close. The thing is that every one wants a different grit. Some like the 60 grit standard wheels because 'a more serrated edge cuts better', while others want 'a more polished edge because there are less serrations to wear down and the edge cuts cleaner and lasts longer'. I also am not much of a skew user, but would think that if you hone your skews, then you would still hone them off the CBN wheels. I don't know if it would be as necessary if you used the 400 grit CBN wheels that Optigrind now carries.

As far as brazed on tips, I have one tool, the Big Ugly, and it is tantung which is silver soldered onto cold rolled bar stock 5/16 thick. I do try to take it to a standard wheel to grind off the cold rolled before I touch up the burr, but if I don't, it doesn't seem to bother the wheel much. I can hear and feel a bump/tick when the softer metal loads up, but a few seconds with a standard scraper removes it all. The tantung seems to pull off most of it as I am sharpening that part too.

robo hippy

 

[john lucas]

I can tell you. It's l about grit size. Not necessarily the wheel material. The Tormec wheel if you use the fine side of the wheel grading stone is supposed to be about 1000 grit. I'm not so sure a out that because I use a 600 grit sanding belt the metal looks more polished to me. However it is a more polished edge than my 180 grit CBN. A 320 grit sanding belt makes a more polished edge than the 180 grit wheel. The 180 grit CBN its as fast as my 120 grit white aluminum oxide wheel and leaves a finer edge than the 120 I think but can't really prove it that an edge that is more polished (meaning finer grit) will hold that edge longer. I e been sharpening my spindle roughing gouge on the 120 wheel and 320 sanding belt alternative for the last year and I am pretty sure I'm correct in my statement but don't really know how to run a true test to find out
There are so many things that affect how cleanly wood is cut that grit size is only one part. Your technique a d how acute the edge is as well as what angle you approach the wood with that edge.
The biggest advantage of CBN wheels are the fact they run true ,stay flat and don't change size. That allows you to sharpen more consistently

 

[Bill Boehme]

I have a Tormek that I bought about 16 years ago and have been using it to sharpen turning tools for 11 years. I took some tools over to a friend who has a grinder with D-Way CBN wheels. My main interest was putting an edge on the large Alan Lacer Slab-O-Steel Skew (ALSOSS). The Tormek is great, but sharpening skew chisels is a slow-go on the Tormek because of the large bevel area. Other tools sharpen just fine on the Tormek. Anyway, I was able to very quickly put a really nice edge on the ALSOSS that was essentially the same as the standard grind on the Tormek. After using the CBN wheel to put a very nice edge on the skew, I was able to use the Tormek to to touch up the edge to surgical-scalpel sharpness, but really it isn't necessary except for things like delicate finials and other frou-frou.

For most tools, the standard grind is what I generally do on the Tormek so I would say that CBN wheels are just about equal to it. With skew chisels I usually use the stone grader to refine the grind and then follow that with a light honing on the leather wheel. I didn't try sharpening a scraper on the CBN wheel, but I still prefer using the Tormek and then put a bur on the scraper using an oval burnishing tool designed for putting a bur on cabinet scrapers. That type of bur is very sharp and strong.

 

[Jerry Rhoads]

Great Article Robo,
really like the looks of the ROBO REST
Thanks for posting

Jerry

 

[Terry Vaughan]

Thanks to all
Terry

 

[Bill Boehme]

Other than my appreciation for your time and effort spent, I have only one other comment about your very well done article, Reed. You stated that you did not notice any appreciable difference in sharpening performance between using a two-pole (3600 RPM) or a four-pole (1800 RPM) grinder motor. Other than speed, the main difference between the two types of motors is torque ripple. The torque ripple in a four-pole motor is much less than it is in a two-pole motor. This can contribute to vibration. However, I suspect that having two large CBN "flywheels" does a lot to dampen the effects of torque ripple.

 

[robo hippy]

Well Bill, you have me scratching my head. It was a while back when I wrote this. I remember saying that I didn't notice any difference in how the different brands of wheels cut. I do remember stating that I didn't think there was much difference between high speed grinders and slow speed grinders. It is easy to understand that higher speeds can make a huge difference in how much wobble there is. This would be very noticeable with standard wheels, but I would expect it to be very minimal with the CBN wheels. Main reason is that they come spin balanced and bubble balances, so they will run a lot truer than standard wheels.

robo hippy

 

[Hu Lowery]

Thank You!

I originally wrote this for Woodturning Design, but right after I submitted it, they folded. It was too long for the AAW Magazine, and I couldn't edit it down far enough for them, so I am posting it on my web site. About 4,000 words. It covers every question I have seen asked on the turning forums.

http://www.robohippy.net/featured-article/

robo hippy

Reed,

An excellent article! I'm still not sure I understand what I need to know about CBN wheels but I am sure I am confused at a much higher level now.

Hu

 

[Bill Boehme]

Reed,

An excellent article! I'm still not sure I understand what I need to know about CBN wheels but I am sure I am confused at a much higher level now.

Hu

What you need to know is is that you need to get a pry bar and force open your wallet.

 

[john lucas]

Bill I used to have a wallet that had a velcro closure. I was buying something once and when at the cash register I opened the wallet with that typical Velcro sound. the lady smiled and said it's been so long since he spent any money he had to tear his wallet open.

 

[Gary Chapman]

Bill I used to have a wallet that had a velcro closure. I was buying something once and when at the cash register I opened the wallet with that typical Velcro sound. the lady smiled and said it's been so long since he spent any money he had to tear his wallet open.

John,
My set up for grinding is the one-way gough and the flat schew or scraper set-up. Shouldent both wheels be similar in grinding grit? Now both my white Norton wheels are 100 grit. What are recommendations on that set-up. One company has a sale on two CBN wheels for $289-Does a 80 grit and a 180 grit wheel sound right for my set-up? Thanks for your help. Gary

 

[Bill Boehme]

... Shouldent both wheels be similar in grinding grit? Now both my white Norton wheels are 100 grit.

Why would you want both wheels to be the same grit? If I were getting two CBN wheels, I would get an 80 and a 160 or 400.

 

[Clifton C]

So I'm thinking the same thing as Gary. Why not two the same? Right now I'm using two 60-grit AO (K-V) wheels and am considering going to two 80-grit CBN wheels. One side is set up for scrapers and free handing and the other for bowl and spindle gouges. I know I'll pull the trigger, right now I'm in the rationalization mode.

I have a spare grinder for making and shaping tools so the CBN wheels would be for sharpening only.
60-grit? I know, but I can get a finish off the tool that even 800-grit sanding film muddies up...

cc

 

[robo hippy]

If you are only going to get one grit, then get one 180 grit wheel, then keep an 80 or coarser grit wheel on the other side. Main reason, for me any way, if I want to change a profile, on either a scraper or gouge, 180 grit is pretty slow. I also keep a standard wheel on one of my 'other' grinders for when I am taking off some non hardened metal. It saves cleaning up the CBN wheel. Another reason to have both an 80 and 180 is that I prefer the burr on my scrapers from the 80 grit wheel. The 180 CBN wheel does make a good burr, but for the roughing and shear scraping I do, I still prefer the 80.

You probably don't need as many grinders as you do chucks though..... I do keep a wire wheel on one grinder. Comes in handy for when you want to clean off dried off gunk from some woods like madrone, or to take the build up off of your chucks and the McNaughton blades. They will take off a burr, but that also dulls the edge and you need to sharpen again.

robo hippy

 

[Clifton C]

robo,
My waffling is cause I’m trying to talk myself into going from a 60 grit to a 180 grit wheel.
AO and CBN aside, I think it would be too much of a shock to my system.
I don’t particularly like the 120 grit AO at the Woodcraft, it seems to load up fast, and, I don’t care for the edge it gives. I’m not sure what the hardness is, so that may be the issue, I use it cause it’s there.
For scraping, I hone off the grinder burr and raise my own, not good, bad or indifferent, it’s just what I like…My scraping is usually for small boxes, exotic wood or whatever is free. Bowls are mostly domestic hardwoods, and I’m a swept back bowl gouge user…
I have to admit, I hone my detail gouges…This is starting to sound like a 12 step program…
I’m a woodturner, but I can quit anytime…
Something I think you answered, but now I cannot find is the equivalency thing,
as in an XX AO wheel is approximately equal to an XX CBN wheel (After the break in period).
Any thoughts on that?

cc

 

[john lucas]

For a while I went the route of having the same wheels on both sides and having the platform on one side and V arm on the other. I rarely use scrapers anymore so I went with a 120 grit white wheel on one side for sharpening some of my carbon steel tools and the 180 CBN on the other. I typically hone off the burr and raise it by hand on my scrapers when I do use them.

 

[robo hippy]

For comparing grits, an 80 grit CBN wheel will take off metal faster than an 80 grit standard wheel. I have no idea why. Also, when broken in, the edge from a CBN wheel looks far more polished. Again, no idea why. Some turners prefer the coarse 60 grit wheels for their bowl gouges because 'a more serrated edge cuts better'. I always thought that was as much because they were free hand sharpeners as anything else, and if you don't have angles set perfectly, you waste time setting the angle, and then you spend more time grinding to get the bevel.

Preferences for scraper burrs is as varied as any other aspect of woodturning. I prefer the 80 grit CBN wheel burr to any I have tried. Mostly for those scrapers, I am using them for heavy roughing, and for shear scraping my bowls. Some woods will get an excellent surface from a shear scrape like madrone or myrtle, but big leaf maple does not do as well. I think this is mostly because of the wood characteristics. For exotic woods, especially if you are doing end grain boxes, you want some thing different. Several recommend that you hone off the burr for cocobolo. Some like the scraper to be sharpened up side down for a 'better' burr. Some like the burnished burr. For my work, a burnished burr is no real improvement that I can see. For some of the exotics, maybe a very gentle burnished burr. I do use a negative rake scraper and burr on end grain box lids and bottoms, but use a small scraper for a shear cut on the inside bottom. I have even burnished a burr on a negative rake scraper. So, maybe like all woodturning, ask 10 different turners the same question and you will get at least a dozen different answers.

John, what do you mostly use scrapers for?

robo hippy

 

[john lucas]

I use them mostly for shear scraping when needed. I use bevel rubbing cutting tools for most things and then will shear scrape with the bowl gouge that has a swept back grind if needed. Most of the time I can get a clean enough cut using gouges or Hunter tools that I don't need the scraper. Years ago I used to use a flat scraper to hollow out my mirrors thinking it was faster. Now I use a bowl gouge on it's side to do a push cut across the grain. That gets rid of the bulk then I do a regular push cut toward the center to clean up those small lines. It's just as fast and I don't have to reach for a second tool. Used to use a scraper for the final shaping and then shear scrape on finishing cuts. Guess I just got away from that after really concentrating on my cutting technique with bowl gouges.

 

[Hu Lowery]

I dearly hate grit all over me

What you need to know is is that you need to get a pry bar and force open your wallet.

Bill,

From time doing a lot of metal fabrication I hate grit all over me. I hate it more the longer I am away from it too. Makes the CBN have a lot of appeal but I don't have a clue what I really want although the 180 grit all around wheel seems like a fine place to start. I almost had myself talked into the wonder wheel with the radiused sides, side flat grind area, recess, yada, yada. Then I got to thinking, I only flat grind a little once in a blue moon and I'm not using a dovetail chuck, don't know that I ever will.

Slammed the sides of the wallet together after putting the credit card back that was starting to wilt a little from the heat anyway. I remembered back when I bought half a two car garage woodworking shop a couple three years ago there was one of the little one inch belt sanders in there. I don't think either my brother or I have staked a specific claim on it. I'm almost certain one inch belts are cheaper than CBN wheels, especially when I don't know which CBN wheels I want. A close call but I think the buy fever passed me by this time!

Hu

 

[robo hippy]

No worries Hu, there are always more things coming out....

robo hippy

 

[Pete Blair]

Cbn

Thanks again Robo. I already have a couple of these but always like to read/see what you produce. How in the heck do you ever find time to turn?

 

[john lucas]

Hu I have been playing with the 1" strip sander. You go through the finer belts really fast. They are cheap, about $3 or so but don't last very long. I haven't used the courser blue ceramic belts yet. They are designed to cut steel so may last a lot longer. I've been using mostly the 320 belt so far. A rough estimate is about 50 belts for the price of one CBN wheel. In the long run I think the CBN would pay for itself and that's just the 5 year warranty period. If it last longer you would save money over the sanding belts. On the plus side it's very fast to change grits and I use it for more than just sharpening.
The 180 CBN will remove metal surprisingly fast. I wanted to regrind a 3/8" scraper into a negative rake. Took a while but not rediculously long and that was a lot of steel to be removed. I would prefer doing that with about 60 grit but I didn't have it. for shaping a new tool occasionally or reshaping a gouge once in a while the 180 will do fine if you have some patience. If you reshape tools frequently I would buy a courser wheel.

 

[robo hippy]

Peter,
I only do one craft show a year now. Mostly I am retired, and make and sell more gadgets than I do bowls. I always wanted to be a coach, so I get to do more of that now. Most of this was filmed about 3 years ago. I had visions of a 3 disc set on bowl turning, and figured the logistics of putting it together would be a pain, requiring a lot of time, so I am putting it up on You Tube. Easier for me that way.

One interesting thing with my turning now is that I am focusing more on a near perfect surface on the inside of the bowl. I can take my time since I have more of it.

robo hippy

 

[Dave Delo]

Hu I have been playing with the 1" strip sander. You go through the finer belts really fast. They are cheap, about $3 or so but don't last very long. I haven't used the courser blue ceramic belts yet. They are designed to cut steel so may last a lot longer. I've been using mostly the 320 belt so far. A rough estimate is about 50 belts for the price of one CBN wheel. In the long run I think the CBN would pay for itself and that's just the 5 year warranty period. If it last longer you would save money over the sanding belts. On the plus side it's very fast to change grits and I use it for more than just sharpening.
The 180 CBN will remove metal surprisingly fast. I wanted to regrind a 3/8" scraper into a negative rake. Took a while but not rediculously long and that was a lot of steel to be removed. I would prefer doing that with about 60 grit but I didn't have it. for shaping a new tool occasionally or reshaping a gouge once in a while the 180 will do fine if you have some patience. If you reshape tools frequently I would buy a courser wheel.

Back about 6 months ago or so when I was looking to upgrade my sharpening set-up from grey 8" wheels, I thought quite a bit about using belts because I have a Shopsmith machine that I've dedicated to be a sanding station. Drum, belt and strip sander on one side of the headstock and straight & conical disks on the other side. Decided against that and went with 80 & 180 grit CBN wheels mostly to stay away from belt changing. However, I have reshaped a couple tools on the 80-grit wheel and they have turned out great, I would have liked to have done the job a bit faster. Nice timing on this thread because I've got a couple other "big-ugly" type scrapers I'd like to reshape. Just need to get a few courser grit belts.

 

[Hu Lowery]

a minor consideration

Hu I have been playing with the 1" strip sander. You go through the finer belts really fast. They are cheap, about $3 or so but don't last very long. I haven't used the courser blue ceramic belts yet. They are designed to cut steel so may last a lot longer. I've been using mostly the 320 belt so far. A rough estimate is about 50 belts for the price of one CBN wheel. In the long run I think the CBN would pay for itself and that's just the 5 year warranty period. If it last longer you would save money over the sanding belts. On the plus side it's very fast to change grits and I use it for more than just sharpening.
The 180 CBN will remove metal surprisingly fast. I wanted to regrind a 3/8" scraper into a negative rake. Took a while but not rediculously long and that was a lot of steel to be removed. I would prefer doing that with about 60 grit but I didn't have it. for shaping a new tool occasionally or reshaping a gouge once in a while the 180 will do fine if you have some patience. If you reshape tools frequently I would buy a courser wheel.

John,

A rainy day and I needed a day off anyway so I poked around looking at metals and sharpening threads today. Cindy Drozda started a thread awhile back and put a blog message on her website, both pointing out that the carbide particles in the A10 tools I am trying to acquire one of here and there are harder than the aluminum oxide in belts.

She believes that the aluminum oxide eats away the supporting metal but doesn't cut or sharpen the carbide. The carbide is left behind or knocked away by the grinder. This would invalidate any testing I did of grits of softer material to compare belts to CBN. I'm not sure she is correct and this is of course just my understanding of what she said. Even so, left me having to do some more thinking. It starts a sizzle going as brain cells fry but fortunately I have some Breyer's Butter Pecan coolant to address that problem.

Now I have to try to source belts that are harder than A10. sigh

Hu

 

[john lucas]

I don't know what she's talking about. don't mean to sound like I'm being down on her I respect her a lot. I just literally don't know what she's talking about. Need to ask her next time I see her. I have done a test on sharpening tool steels. I sharpened High carbon steel, High Speed Steel and Particle Metal steel. I ground them all to the same angle and sharpened them the best I could. All of them sharpen to the same high degree. I was trying to either verify or disprove the often stated fact that High Carbon steel would sharpen better than HSS. I also heard people saying that Particle Metal steel couldn't be sharpened to a high degree. Well what I found out was that all 3 steels could be sharpened to the same high degree. It could be that microscopically one can be better than the other. However in my test they all cut the same. I tried shaving hair. All take off hair easily. Cutting paper. They cut it like butter effortlessly. I tried a test that I use to test my carving tools. I cut end grain at an angle so it produces a pointed peak. A less than very sharp tool won't do that. All 3 of these did. I could not tell that one was sharper or less sharp than the others. I used sand paper up to 1500 grit and then stropped them using leather and green honing compound.
Now could the medium you use to sharpen it be a consideration. I think it is possible but probably because there may be different ways to evaluate the grain size. In other words a 180 grit sanding belt may not cut exactly the same as a 180 grit CBN wheel. Why I don't know. It is known that some abrasives are better at sharpening certain steels. However I haven't really been able to tell the difference. If it makes 2 edges come to a point then the scratch pattern produced by the grit is what matters. The finer the grit the sharper it gets if the metal can handle it. Older carbides such as router bits would not sharpen to a really keen point. The metals we use in turning tools will. Well as far as high quality gouges go. Can't talk about the new carbide tools because other than the Hunter tools I haven't tried sharpening them to the same degree. Hunter cutters are very sharp from the factory and cannot be sharpened. At least that's my experience and I tried a lot of different abrasives.
OK that's the long way around what I was trying to say. Which is pick a medium that works for you and learn to use it. It will give you a sharp edge. there are other reasons to pick one over the other such as cost, wear of the material, ease of use etc but all work. The trick to sharpening turning tools is to pick something that is easy so you do it often (but then you know that) And then pick a grit that gives you the edge you need.

 

[robo hippy]

Well, the Thompson tools are V 10 (10% vanadium) which is a particle metal rather than forged steel. Carbide is a different type of particle metal. There has been discussion by the metal heads that standard wheels will grind off/knock off the particles, but not shave tiny bits off of the particles like CBN does, if that makes any sense. This is supposedly why the CBN wheels will sharpen the powder metal better than a standard wheel.

robo hippy

 

[Hu Lowery]

reed is correct in his understanding I believe

I don't know what she's talking about. don't mean to sound like I'm being down on her I respect her a lot. I just literally don't know what she's talking about. Need to ask her next time I see her. I have done a test on sharpening tool steels. I sharpened High carbon steel, High Speed Steel and Particle Metal steel. I ground them all to the same angle and sharpened them the best I could. All of them sharpen to the same high degree. I was trying to either verify or disprove the often stated fact that High Carbon steel would sharpen better than HSS. I also heard people saying that Particle Metal steel couldn't be sharpened to a high degree. Well what I found out was that all 3 steels could be sharpened to the same high degree. It could be that microscopically one can be better than the other. However in my test they all cut the same. I tried shaving hair. All take off hair easily. Cutting paper. They cut it like butter effortlessly. I tried a test that I use to test my carving tools. I cut end grain at an angle so it produces a pointed peak. A less than very sharp tool won't do that. All 3 of these did. I could not tell that one was sharper or less sharp than the others. I used sand paper up to 1500 grit and then stropped them using leather and green honing compound.
Now could the medium you use to sharpen it be a consideration. I think it is possible but probably because there may be different ways to evaluate the grain size. In other words a 180 grit sanding belt may not cut exactly the same as a 180 grit CBN wheel. Why I don't know. It is known that some abrasives are better at sharpening certain steels. However I haven't really been able to tell the difference. If it makes 2 edges come to a point then the scratch pattern produced by the grit is what matters. The finer the grit the sharper it gets if the metal can handle it. Older carbides such as router bits would not sharpen to a really keen point. The metals we use in turning tools will. Well as far as high quality gouges go. Can't talk about the new carbide tools because other than the Hunter tools I haven't tried sharpening them to the same degree. Hunter cutters are very sharp from the factory and cannot be sharpened. At least that's my experience and I tried a lot of different abrasives.
OK that's the long way around what I was trying to say. Which is pick a medium that works for you and learn to use it. It will give you a sharp edge. there are other reasons to pick one over the other such as cost, wear of the material, ease of use etc but all work. The trick to sharpening turning tools is to pick something that is easy so you do it often (but then you know that) And then pick a grit that gives you the edge you need.

John,

Reed is correct in his understanding of what Cindy and others are saying I believe. After reading metallurgy for hours today I'm not sure there are harder particles remaining in a harder matrix which seems to be the belief of some. If they are indeed correct that there are harder particles of any significant size then while the softer grinding materials may put an edge on the particle metal steels they do it by tearing out the hardest part of the metal and sharpening the softer matrix that was holding these particles. Sharpening with a diamond hone cuts back to the harder stuff or the softer metal is quickly worn away when turning leaving a duller but stronger edge.

Convoluted language in the above paragraph because I am trying to convey my understanding of what others believe. I think the metals in the final stage may be more homogenous than some believe. This article I studied earlier today has been linked to in the past:

http://www.morewoodturningmagazine.com/reviews/Tool Wear Testing by Jim Staley.pdf

They found that V10 was very little superior to properly heat treated M2. They both finished at roughly 60-62 Rockwell too I believe. However, they found that V15 was about 2.5x better than either because the harder particles were both smaller and more evenly distributed. This would support the beliefs of Cindy and others.

Doug Thompson does not endorse V15 the last I knew believing it is too brittle as one reason he gives. It isn't offered but in one tool he makes that I could find and they are in very limited quantities. I suspect he has difficulty obtaining V15.

Just as a by the by, it would seem that V15 would sharpen better than V10 using aluminum oxide from what I gather.

When push comes to shove I think I will fool around with what I can sharpen with without spending much money. I have a couple of carbide tools I don't really care for but they are made by the people that made my hollower, one V10 that I have only honed so far, and one or two M2 tools.

That article seems to take two very similar criteria to add together but it looks like they still come to the proper results looking at the micro images. Good M2 and V10 seem about the same. M2 is often far softer best I recall and something between 40-45 Rockwell isn't going to compete with something at 62 Rockwell.

Some metals are tougher than others in ways that are difficult to measure. They are the same hardness but one resists cutting more when trying to machine and it also resists erosion from heat and pressure. Getting into some of the more involved areas of metallurgy are probably way past my abilities but numbers alone rarely tell the whole story. I doubt anyone using the particle steel tools will agree that M2 is just as good for example. Wish we could test some of the stuff V15 or higher too. Might get so brittle it can't stand the shock or it might be that the price gets to the point that we would have to put a small piece in a holder like carbide.

I don't know, read until it is all a blur today!

Hu

 

[robo hippy]

I would argue that there is a significant difference in edge wear between the V10 and standard M2 HSS. Yes, all M2 is not the same, but I am talking about the good stuff. While the rockwell hardness is pretty close, there are other things that come into play, and I can't specifically say what, but the V10 does keep an edge longer. I notice it on my scrapers as well, comparing Doug and Dave's tools to standard M2. I still want a fresh edge for finish cuts though.

robo hippy

 

[Hu Lowery]

I think we are in agreement there

I would argue that there is a significant difference in edge wear between the V10 and standard M2 HSS. Yes, all M2 is not the same, but I am talking about the good stuff. While the rockwell hardness is pretty close, there are other things that come into play, and I can't specifically say what, but the V10 does keep an edge longer. I notice it on my scrapers as well, comparing Doug and Dave's tools to standard M2. I still want a fresh edge for finish cuts though.

robo hippy

I think we are in full agreement, everything about a material doesn't show on paper. Bumped into that a good many times, sometimes to my benefit, sometimes not!

In my looking I found a pretty nice metal that is fairly moderately priced as such things go, PM-M4. This isn't the same beast as M4 at all. It is a powdered metal with good wear resistance, good toughness meaning it can stand a shock, poor red heat which we don't care about, and good grindability. Available from very small in 1/16" divisions too. Wouldn't be surprised if it was the mystery metal a few people don't want to name. Seems like the bee's knees. Wonder if somebody would grind up a stick of it for us?

I could easily spend more time playing with tooling than turning, kinda what happened to my pool cue shop. I spent more time cutting in the machine shop next door handling overflow work than I spent in my own shop!

Hu

 

[Bill Boehme]

robo,
My waffling is cause I’m trying to talk myself into going from a 60 grit to a 180 grit wheel.
AO and CBN aside, I think it would be too much of a shock to my system.
I don’t particularly like the 120 grit AO at the Woodcraft, it seems to load up fast, and, I don’t care for the edge it gives. I’m not sure what the hardness is, so that may be the issue, I use it cause it’s there.
For scraping, I hone off the grinder burr and raise my own, not good, bad or indifferent, it’s just what I like…My scraping is usually for small boxes, exotic wood or whatever is free. Bowls are mostly domestic hardwoods, and I’m a swept back bowl gouge user…
I have to admit, I hone my detail gouges…This is starting to sound like a 12 step program…
I’m a woodturner, but I can quit anytime…
Something I think you answered, but now I cannot find is the equivalency thing,
as in an XX AO wheel is approximately equal to an XX CBN wheel (After the break in period).
Any thoughts on that?

cc

You won't have any need for even the slightest bit of paradigm shifting when transitioning from using an 80 grit AO stone to using a 180 grit CBN wheel. It took me all of one tool sharpening to feel perfectly at home with CBN. You can't really compare AO grit sizes to CBN grit sizes because the cutting mechanism is so different that grit size comparison as a means of predicting sharpening performance becomes meaningless.

I don't like the Woodcraft 120 grit AO stone either ... it is way too hard. For best performance, it should have a hardness of J or K. Besides, a 120 grit AO stone is too fine for lathe tool sharpening if you want my opinion.

If you get only one CBN wheel, then get a 180 grit. That should give you the closest "equivalence" to 80 grit AO stone. An 80 grit CBN would be somewhat comparable to 43 grit AO.

 

[john lucas]

My understanding of why Doug doesn't sell the V15 was simply money. It is a lot more expensive than the V10 which of course means the tools would be more expensive. I haven't talked to him about that lately so there may be other reasons. I have a V15 skew that he made early on before deciding that he wouldn't use it. It is not brittle at all. Holds a great edge and will get as sharp as any tool I have. I started studying the Particle metal steels fairly early on because I had to photograph a factory here in Tennessee that makes particle metal parts for all sorts of industries. They can formulate it to have all sorts of capabilities. They can make it porous so it holds oil better is one example. They vanadium content is what gives it the toughness to hold an edge without chipping. The coolest thing about particle metal is it can be stamped into shape. The powder of various particles depending on the use of the part is poured into a mold and then stamped under high pressure into shape. Then it goes through a sintering process to melt the metal together. The factory where i photographed made gears for drills that were stamped within a .001" of accuracy and then one milling operation was performed to insert the bearing. This same part took 7 machining operations to make before this process came about.
Wish I had time to do serious testing but in reality I just want to turn and whatever tool does the job is fine with me. I've gone to mostly Thompson particle metal tools because they do the job. I will keep trying to learn more about sharpening because it's fun and I like a sharp edge.

 

[robo hippy]

Doug also commented that the V10 was difficult to work with, and the V15 was even more difficult to work with. Really hard on the cutters and abrasives. I did get one sample from Serious tools of a 'very hard' metal, which could have been V15. It was nice, but I didn't like the flute design at all. For scrapers (the Big Ugly), the best metal I have found is tangung which is a cast metal, and stellite which is what the cutting tips on the Woodcut coring system are made from. I can turn for half a day without having to refresh the burr. The tangtung is difficult to find as they make most of it for small cutters as in 1/8 inch square. The stellite comes from up in Canada. Silver soldered onto bar stock with a thick solder tape. Still trying to figure that one out.

robo hippy

 

[Hu Lowery]

still rambling through metal sites

Too cold to go outside, still looking at metals.

Where I can get prices without requesting a quote and dealing with salespeople CPM-15V is 67% higher priced than CPM-10V. It also offers almost twice the wearability so 15V is actually cheaper over the life of the tool. When it comes to shaping or sharpening the alloys, both fall around 30-35% of the machinability of 1% carbon steel which I assume is mild steel. The people that make it say to use CBN or a special ceramic aluminum oxide to shape or sharpen it. I couldn't find the SG wheels to fit standard bench grinders, perhaps a seven inch wheel, no real information. However, using any of the more common aluminum oxides flattens the grit on the wheel or belt and is not the preferred method of sharpening 10V or 15V per the maker.

I haven't looked for other sources but a bit of trivia or maybe something useful to someone that frequents gun shows and such, stellite is used for some machine gun barrels. I think it gives about fifteen times the life of a standard barrel at about fifteen times the cost. A wash in terms of life but saves a lot of labor and of course the barrel doesn't fail in combat. One barrel would be a lifetime supply of stellite, might cut with a water cutter but I don't know.

It is interesting to explore all of this, I even found the steps of how CPM is made. In the end I think the KISS rule applies for me though and quality M-2 may indeed be better than the 10V with the sharpening equipment I have. I think I will still buy CPM when I can, when I get enough tools I'll have to upgrade to CBN wheels!

Hu

 

[john lucas]

I've been sharpening my 10v and 15V on the same wheels I did for years up until I got the CBN. Works fine for me. I just touched up my bowl gouge on my older White Aluminum Oxide wheel simple because I had the V arm there from my last session. I was too lazy to change it over. It worked just fine. I'm currently packing to move so everything is in disarray which is why it was easier to just sharpen it than change things over. I still have 2 projects to somehow get done before I have to pack the lathe and grinder. One day I did a test using my Tormek with the standard wheel, my belt sander with Klingspor Gold belts and my CBN wheel to sharpen my V15 skew. I could not tell the difference except the Tormek was slower (Duh it's a really slow speed grinder) I do hone afterwords to get it really sharp so the difference in grit size of the 3 was a non issue.

 

[hockenbery]

It is interesting to explore all of this, I even found the steps of how CPM is made. In the end I think the KISS rule applies for me though and quality M-2 may indeed be better than the 10V with the sharpening equipment I have. I think I will still buy CPM when I can, when I get enough tools I'll have to upgrade to CBN wheels! Hu

Hu

I have mostly m2 tools and three Thompson gouges. They all sharpen fine on my Norton 3x wheels.

I used a CBN wheel this summer for a few days and was impressed by how smooth it felt under the tool.
Almost like a frictionless sharpening if that is possible. I also think if I had mostly v10 tools the CBN would be on the shopping list.

I also do not see a longevity advantage to the edge holding of the v10 tools.
I sharpen when I start, sharpen when I'm doing finish cuts. So I'm sharpening a sharper tool when it is v10.
If I used tools until they were an unusable dull I would probably see more difference with the v10.

If it stays cold long enough you can teach us more stuff
Thanks for the research,
Al

 

[robo hippy]

In my search to find out how to make an inside S curved bowl rest at 15 degree angle die, I found this method of cutting:

http://en.wikipedia.org/wiki/Electrical_discharge_machining

Really interesting. I think it is like the laser cutting or water jet cutting. Not great for any production stuff unless the material is very thin, less than 1/2 inch or so. It has been around longer than I have.

robo hippy