CBN intermediate report

[Ken S]

My CBN testing is nearing completion. Enough time has passed that I want to post an intermediate report.

I would compare using CBN wheels with the Tormek to having a trailer hitch on a truck or SUV. For someone who actually pulls a trailer, the hitch is essential. For those of us who might like to someday need a trailer, a hitch is an expensive, but convenient means to hold a cute ornamental propeller or add some swagger to our step at the parking lot of the local McDonald's.

With CBN, it is a major stress reducer for a turner reshaping one of his gouges or skews. I would place it on the essential list for frequent reshapers and certainly for planer blade resharpeners. In both cases I would follow up with a conventional Tormek wheel and leather honing wheel for final polishing. With CBN, you get to that point more quickly with a lot less stress.

Using the combination of the Tormek and CBN wheels lets you use the strengths of both. I purchased the Tormek to handle the heavy lifting part of sharpening my chisels and plane blades. It does this very well; the Tormek SG is still my wheel of choice for this work. For sharpening kitchen knives at home or routine sharpening of turning tools, I see no need for another wheel. I like the cool, dust and spark free Tormek which proceeds at an efficient pace and still allows me full control.

What the Tormek SG wheel does in this use, the CBN wheel does for heavier grinding of harder steels. With high carbon chisels, the SG and CBN are evenly matched for speed. For sharpening just dull high speed steel tools, the SG does a respectable job. For anything heavier, like reshaping a turning tool or sharpening a planer blade with nicks, it's no contest. The CBN shines.

My standard test for grinding wheels using harder steel is to place a new metal lathe bit in a square edge jig set for a 25° bevel and grind for five minutes. In this test, the180 grit CBN wheel and the 220 grit Tormek wheel seem to start out cutting about the same. The difference occurs during the cutting process. By the end if the fuve minutes, the CBN wheel is still cutting as well. The SG has slowed down considerably. This should be no surprise. The SG is designed for carbon steel, like chisels and plane blades. It will work with harder steels, but is no match for the CBN, which is designed for harder steels. On the other hand, softer steel would clog a CBN wheel.

At this point, I am convinced the CBN wheels work well with the Tormek, either dry or wet (with Honerite Gold). Dave Sweitzer has generously offered to provide me with 360 and 600 grit wheels (presently for the T4 in eight inch diameter). My further tests will include these grits. I will keep you posted.

Ken

[bobl]

looking forward to more results Ken.
Keep on Grinding Sir.

[grepper]

Thanks, Ken, for providing these CBN wheel reviews!  I'll be looking forward to your 360 and 600 grit results.  I'm curious as to what you think of a knife sharpened with the 600 grit wheel and a good honing.

Also, say thanks to Dave Sweitzer for magnanimously lending you the wheels for review. 

[Ken S]

Thanks, Grepper. I will keep everyone posted and let Dave know we appreciate his generous help.

Ken

[Rob]

My CBN testing is nearing completion. Enough time has passed that I want to post an intermediate report.

I would compare using CBN wheels with the Tormek to having a trailer hitch on a truck or SUV. For someone who actually pulls a trailer, the hitch is essential. For those of us who might like to someday need a trailer, a hitch is an expensive, but convenient means to hold a cute ornamental propeller or add some swagger to our step at the parking lot of the local McDonald's.

With CBN, it is a major stress reducer for a turner reshaping one of his gouges or skews. I would place it on the essential list for frequent reshapers and certainly for planer blade resharpeners. In both cases I would follow up with a conventional Tormek wheel and leather honing wheel for final polishing. With CBN, you get to that point more quickly with a lot less stress.

Using the combination of the Tormek and CBN wheels lets you use the strengths of both. I purchased the Tormek to handle the heavy lifting part of sharpening my chisels and plane blades. It does this very well; the Tormek SG is still my wheel of choice for this work. For sharpening kitchen knives at home or routine sharpening of turning tools, I see no need for another wheel. I like the cool, dust and spark free Tormek which proceeds at an efficient pace and still allows me full control.

What the Tormek SG wheel does in this use, the CBN wheel does for heavier grinding of harder steels. With high carbon chisels, the SG and CBN are evenly matched for speed. For sharpening just dull high speed steel tools, the SG does a respectable job. For anything heavier, like reshaping a turning tool or sharpening a planer blade with nicks, it's no contest. The CBN shines.

My standard test for grinding wheels using harder steel is to place a new metal lathe bit in a square edge jig set for a 25° bevel and grind for five minutes. In this test, the180 grit CBN wheel and the 220 grit Tormek wheel seem to start out cutting about the same. The difference occurs during the cutting process. By the end if the fuve minutes, the CBN wheel is still cutting as well. The SG has slowed down considerably. This should be no surprise. The SG is designed for carbon steel, like chisels and plane blades. It will work with harder steels, but is no match for the CBN, which is designed for harder steels. On the other hand, softer steel would clog a CBN wheel.

At this point, I am convinced the CBN wheels work well with the Tormek, either dry or wet (with Honerite Gold). Dave Sweitzer has generously offered to provide me with 360 and 600 grit wheels (presently for the T4 in eight inch diameter). My further tests will include these grits. I will keep you posted.

Ken

Interesting Ken,

and I'm right to assume that a CBN wheel needs no dressing ever?  Ie it never loses its shape? Also does it perform well being doused in the water trough ie can you safely grind wet with it?  Lastly, if you do smear some sort of honing compound on it, how does it respond to that...does it clog it and then need cleaning?  Is there any concern about rust after a wet session with it or is it free from steel so immune?

[Ken S]

Rob,

CBN does not need dressing. If it gets clogged from grinding soft steel, the standard cure is just to grind some hardened steel.

I have heard a few stories about a hollow wearing in the middle. This seems to be unusual, and in the case I know about, the vendor replaced the defective wheel.

CBN wheels cut much more coarsely and then settle down to their intended grit.

I have used them wet and dry. When I use them wet, I use the standard dilution (1:25) of Honerite Gold to water. Honerite Gold, made in the UK, is a liquid which prevents rust. My tests indicate it works well. The solution goes into the water trough. It is liquid and does not clog anything. As a precaution, when I am through sharpening, I wipe the wheel and bushing with oil before hanging it up. (I don't normally store any grinding wheels mounted on the Tormek.

CBN also works very well dry. A magnet can clean up the steel grindings. I suspect most users will prefer to use them dry.

The 80 and 180 grit wheels are designed for turners.They make the Tormek a reshaping machine. I have thought about you and your planer blade frustrations. I think either the 80 or 180 CBN wheel would solve your problems, removing the nicks.I would finish up with a finer Tormek wheel, giving you the best of both worlds.

I will post more soon.

Ken

[Rob]

Thanks Ken

I rather thought you might have had my shaping challenges in mind.  But as you say, particularly with the 80 grit wheel, I can see me having another session with the planar blade jig because there is a hidden benefit.  Not only is the cbn grit far more abrasive (and therefore more efficient at grinding into ultra hard steels like my planar blades) but because it doesn't lose it's shape my jig settings can be maintained.  One of the problems I had when attempting the planar blades with the SB was the only means of getting it to cut the metal was to grade it with the diamond truing tool.  You know how abrasive it becomes after a truing session as it exposes all the new rough surface like no other method.  That procedure got it cutting for a short while before it glazed but in the process of re-truing it it would subtly reduce the wheel diameter which would, in turn, throw out the jig settings (which have to be quite fine for the planar jig).  With a wheel that doesn't require dressing, that problem will never occur.

So you have given me hope my friend :-)

Of course we will conveniently forget to mention that the cost of a cbn wheel would probably pay for 4 or 5 professional sharpening services on my planar blades which may last me a lifetime!!  But the saving justification is the shaping of HSS gouges....nice work fella....you've handled all my objections before I can even ask them :-)

[Ken S]

Rob,

I have actually had you in mind for quite some time, going way back to my work using the Norton 3X wheels with the Tormek. One 3X wheel, either the 46 or 80 grit, and some fiddling with plastic pipe could solve your reshaping problems for around $50 US. True, the CBN wheels cost more, however, they are wider, more convenient and work better. Whereas a turner who did only minir reshaping might get by with either the Tormek wheel or the 3X, the more frequent reshaper would definitely appreciate CBN.

I think a CBN wheel would be a good second wheel for a Tormek turner. Like you, I have found the SB cuts very well immediaely after retruing. And, also like you, I have not figured out how to get past the glazing. I have not encountered glazing with CBN.

I prefer the feel and finer edge of the SG for high carbon tools. For a non turner, there is little need to go beyond the SG. I know one woodworker who actually finishes his planer blades with the SJ 4000 grit wheel. He works to a very high standard. He is also unconcerned with production timetables.

Rob, I look forward to "seeing you on the other side" (our new forum reprogram on Monday).

Ken