How do you like your CBN (Cubic Boron Nitride) grinding wheel?

How do you like your CBN (Cubic Boron Nitride) grinding wheel? They sound too good to be true but reading about them makes me believe they're legit and I think I will get one. Traditionall uses to grind cams/crankshafts, etc.
How do you like yours?
Benefits over alox and others: 1. dissipate heat very well, comparable to a wetstone 2. no dressing required, stay straight/true 3. no dust 4. won't come apart 5. last much longer
Downsides: 1. I don't know, you tell me
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I've got 2 80 & 180 grit. Use them for sharpening HSS turning tools. No dust from the wheels, but I do get steel dust from grinding. Everything that I have read advises not to use them for non hardened steel. Tools don't get hot unless you really push them into the wheels (which you shouldn't do with any wheel). They cut quick, and don't need to be trued. Which means that I can mark my sharpening jig for different grinds (spindle gouge or bowl gouge) and switch back and forth accurately, maintaing the correct grinding angle. The grit is electro plated to a steel disk, so no worries about it coming apart. I took the guards off of my grinder, so that I could mount 1 1/2" wide wheels. They will outlast me. They run much truer than any stone wheel that I ever had. They are expensive, but worth it. The price does vary, so shop before you order,
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On Saturday, December 27, 2014 1:09:58 PM UTC-8, Electric Comet wrote:

Diamond wheels are chemically unstable in contact with hot ferrous alloys (hot iron dissolves carbon). So, cubic boron nitride (Borazon) is often used instead. It's close to diamond in hardness, and about twice as expensive per gram if you buy the grit. It's a manmade material, like silicon carbide.
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On 12/27/2014 9:48 PM, whit3rd wrote:

So in researching the issue. It seems that the home machinist group shares this concept.
But in looking at a German company that makes both, diamond and cbn. They do not mention any problems with diamond, but do not metion in it the use of HSS. On the other hand CBN is metioned, and it must be kept cool so as not to crack or weaken the edge of HSS tools. So I am assuming CBN to be the preferred tool for HSS. But I do know that many CNC machines use diamond to grind carbide.
     The decisive difference between diamond and CBN:
Diamond
Diamond is pure carbon and the hardest of all known materials. Due to its hardness, diamond has become increasingly important for machining in state-of-the-art technology. Today synthetic diamond grit is the material preferably used in abrasive engineering practice. The starting substance is carbon in the form of graphite. The synthesis occurs after extreme pressures and temperatures are applied. Due to its fine crystalline structure and the resulting properties, e.g. maximum abrasion resistance and edge-holding quality, diamond is superior to all other abrading media. Diamond belongs to the “super hard” group of cutting materials.
Diamond is restricted by its thermal load capacity if subjected to temperatures exceeding 700°C, e.g. when grinding steel materials
Applications
Materials that can readily be machined with diamond tools include: welded and thermal sprayed alloys, electrocarbons, precious and semiprecious stones, ferrite, fireproof materials, glass-fiber and carbon-fiber reinforced plastics, glass, graphite, semiconductor materials, hard metal, ceramics, natural and artificial stones, oxide ceramics, porcelain and quartz. In exceptional cases cast steel and gray cast iron can also be machined with diamond tools.
CBN (cubic boron nitride)
CBN is a 100% synthetic product which is the second hardest abrading medium after diamond. Due to its chemical-physical properties, CBN is primarily used to process hard-to-machine steels with a high alloy content and/or hardness. The CBN abrasive grain is manufactured using virtually the same synthesis technique as for synthetic diamond abrasive grain. The starting substance for CBN is hexagonal boron nitride. Like diamond, CBN belongs to the “super hard” group of cutting materials.
Application
CBN can withstand temperatures of up to 1300°C and has a slight tendency to react chemically to metals. Due to its fine crystalline structure and the resulting properties, e.g. a high abrasion resistance and edge-holding quality, it offers advantages in comparison to conventional abrading media, especially for grinding hard-to-machine and hardened steels >55HRC, e.g. HSS or chrome alloyed steels. Lowering the temperature during grinding prevents changes in the structure of the material edge zone, and therefore grinding cracks and soft skin formation. High accuracy regarding dimension, shape and concentricity as well as long tool life can thus be achieved using CBN grinding tools.
--
Jeff

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On 12/27/2014 4:08 PM, Electric Comet wrote:

add to 4, so you don't need a guard.
So you can use the edge to create unique profiles. There are sharp edged and rounded edged wheels.
I still think, if you going for this, you might as well go for diamond. But this is a good alternative at a good price point.
--
Jeff

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On Sat, 27 Dec 2014 20:54:07 -0500

The only downside is higher price but it pays for itself due to long life and the upsides outweigh that downside. Which really isn't a downside.
Good to hear first-hand experience. I think I will go with the 180 grit.
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On 2014-12-28 19:39:43 +0000, Electric Comet said:

We've had a CBN for some years now, we were taking a class via the local woodturning club and D-Way Tools provided the grinder (the owner is a member). The DW came back from sharpening her tool as said "as soon as we can afford it, we are getting one:
Dave (D-Way Tools) figures for even a production Pro turner, a CBN wheel is a life-time buy.
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On Sun, 28 Dec 2014 11:51:55 -0500

Which also means a wider wheel can be used.

Some wheels also have grinding surface on the side of the wheel. So you have two surfaces to grind against.

No, diamond is not comparable for this use. I read that the other elements in steel cause problems with diamond wheels. I believe this fact is what inspired GE to create CBN grinding surfaces.
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On 2014-12-28 19:49:26 +0000, Electric Comet said:

Diamond sux for HSS or HCS, the carbon from the diamond can (and does) modify the carbon content of the tool and you end up with a steel with the wrong carbon content
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On 12/28/2014 10:04 PM, Ralph E Lindberg wrote:

I have never heard that before. I'll double check that.
I know heat changes the steel, you can change the grain size and stability, but I had not heard that diamond would change the carbon content. I didn't think they were exchaning chemical make up, as the diamond cut with minimal heat.
--
Jeff

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On Sun, 28 Dec 2014 19:04:11 -0800

Seems to be the other way around. The tool modifies the diamond wheel and now you have a ineffective diamond wheel and that hurts.
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On 12/29/2014 12:46 PM, Electric Comet wrote:

That's true about soft metals ruining diamond and cbn wheels. But hard metals should just cut and that's it.
--
Jeff

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On Tue, 30 Dec 2014 12:08:28 -0500

The CBN wheels I've looked at seem to have enough metal to dissipate the heat and keep cool. Unless too much force is applied. The other posts and sites say that the wheels stay cool and I read that they stay as cool as a wet wheel.

Does this fact contradict? Or does this follow? What do cnc machines use? Tungsten carbide? You mean metal-work cnc?
I noticed that Laguna has a CNC wood lathe and now I wonder what they use for the cutting tool.
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On 1/1/2015 12:11 PM, Electric Comet wrote:

I saw a video from one of the magazines that showed how Jesada (shitty company) prepares it's carbide router bits (for wood working). They use cnc diamond grinding in their machines. Using coolant of course. All high speed grinding and cutting operations use coolant to keep the tool from burning up and the cutter from destroying itself.
--
Jeff

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Some more info I came across:
CBN Coating CBN stands for Cubic Boron Nitride, an abrasive grain that's nearly as hard as diamond but much better suited for sharpening hardened steel. Sharpening on diamond wheels produces heat, and from around 170°C causes a chemical reaction between the diamond grain and the steel alloys which destroys the diamond grain. CBN, on the other hand, only reacts at above 400°C, and is only destroyed at 700°C and above.
http://www.mehr-als-werkzeug.de/product/704846/OptiGrind-CBN-Grinding-Wheel -Grit--150-x-20-mm.htm
139€ including VAT
Don't know the exchange rate to usd
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On 1/10/15, 10:05 AM, Electric Comet wrote:

Similar @ $94 (watch out for any line wrap) http://www.use-enco.com/CGI/INSRIT?PMAKA91-5716&PMPXNO 2558&PARTPG=INLMK32
-BR

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