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What grit CBN?

John Hicks

John Hicks

Joined
Jan 23, 2020
Messages
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Location
Shingletown CA
I usually use a Sorby proedge for all my sharpening. About a year ago, I bought a Rikon 1hp slow speed grinder and the wolverine setup. I tried it with the original white wheels, but could not get them balanced. About 4 months ago I bit the bullet and got two cbn wheels from wood turners wonders. One wide 180 grit; and one radius 350 grit. I found the 350 heats up metal pretty quick, and does not really put a burr on scrapers. The 180 seems to be a better choice for general purpose. What grit wheel is good for putting a burr on scrapers?
I'm finding the proedge to be more to my liking for general sharpening. On that machine, I use a 120 grit ceramic belt, and a trizac belt (600 grit) for touching up gouges.
I have all hss tools, one v10 gouge, a few m2 cryo tools, and a mess of m42.
 
I have found Robo Hippy's advice to burnish the burr to be spot on, as I get a better burr that lasts longer. Otherwise, I believe my 180 wheel makes a better burr than my 320.
 
I use 80 grit CBN for scrapers and 180 grit for my Thompson gouges. I have tried higher grits and while they may get the gouges a little sharper I have found that the 180 grit gives me the longest cutting time between sharpening. So most of the other grinders have 180 grit CBNs. I do keep 1 wheel on one grinder with a stone for rough shaping.
 
I use the 180 grit 98% of the time. I do have 320, 600, and 1000. I don't think there is much of a step up in edge sharpness from the 180 to the 320. There is a pretty significant one from 180 to 600. The 1000 grit needs more experimenting, but I do like it for my skews, and yes, I do actually use them some times. Even with a 1000 grit wheel, you need to polish/strop the burr off, it makes a huge difference.

As for burrs on scrapers, I still use the 180 grit most of the time. Some times with my dedicated shear scrapers, I will use the 600 grit wheel for that burr, and some times I will burnish the grinder burr off, then raise another up on it. The burnished burr is superior to the grinder burr. It isn't always necessary though. For 'difficult' woods, yes. For most woods, no.

I do have one set of the radius edge wheels and don't care for them. If I did a lot of hollow forms, then I could use them more.

robo hippy
 
I also use the John Jordan jig to sharpen hollowing cutter bits. It requires that you remove the bit from the hollowing bar first. The John Jordan hollowing bars hold the bit with a set screw, so it's pretty easy to remove.

I believe the radiused wheels are more useful for hollowing tools, like the Trent Bosch bars or the David Ellsworth bars, where the bit is held in the hollowing bar with CA glue, making it more of a hassle to remove. A radiused wheel works better for sharpening the bits while they are still in the hollowing bar.
 
The radius edge was a Dave Ellsworth idea. Since I do almost no hollow forms, I can't really remember how I sharpen them, other than kind of freehand on the platform. About a 70 degree bevel angle.

robo hippy
 
I finally got the 1 HP Rikon ordered and will use the wheels that comes on it until you all can make up my mind which CBNs and jig to use...;). I know I want to make some boxes, hollow forms. Up to now, I have resisted buying any carbide tools, have chosen to hone my chisels and chisel skills. It appears the carbide tools are for the most part used for hollowing and I'm kinda leaning toward the cupped Hunter carbide tools so big square wheels should work for me.
It looks like the 180 grit wheel is used the most by everyone. So my thoughts are one 180 grit CBN and one good aluminum oxide on the Rikon. I have for many years used paper wheels on an old Dayton to hone knives that I put a burr on with a 1" wide 320 grit belt sander. This also works with my chisels. I've been experimenting with an extra wheel, reshaping it for the inside edges of fluted gouges.
I've heard several comments about cracked, unbalanced Rikon wheels so was wondering if I need to purchase a different aluminum oxide wheel for shaping and what grit that should be. Then there is wheel dressing needed for that wheel, Thanks again, much appreciate everyone's wisdom and experience...
 

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The servicability of the Rikon wheels appears to be a matter of luck. I've had good ones, though they've been replaced by CBN. They can certainly do the job, and have been doing so for lots of turners for a long time. A $15 T-handle diamond dresser works fine for most needs. There are ways to deal with any wobble in the stone wheels, if you find some in yours, almost always. But no need to worry about the wheels until you get some. Then if you find you have some, drop the forum members a note and you'll get a half dozen recommended solutions.
 
Thanks for the info Dean, and though the different solutions given are sometimes confusing and conflicting, one of those solutions fits my situation to the tee, I guess it then makes me one of those that believe that...
 
When Rikon came out with that 1/2 HP slow speed grinder it was at a time when it was nigh impossible to find a slow speed so I bought one. Out of the box this thing ran absolutely true, had never had that happen before. I put 2 1" CBN wheels on it and although it took a few seconds to get going it took about 13 minutes to quit turning after it was shut off. I put one of those white wheels from that Rikon on another grinder in the shop to have one roughing in stone and it has been running for 4 or 5 years now without a problem and the other from that grinder is new in a drawer.
 
Well that's good news, maybe mine will arrive in good shape. I debated the 1/2 HP but as my luck runs the start windings or capacitor would burn up five years and a day after I bought it...
 
I have 2 of the 1 hp Rikon grinders. For the money, they are a good grinder. The first one had wheels so far out of true that I wouldn't give them to some one I didn't like. I did take the rubber feet off so I could bolt it down to plywood for mobility. The base needed 1/8 inch ground off of one leg to get it to sit flat. The second one, maybe 2 years later had wheels that ran fairly true, and the base was flat. I also removed the lamp that came with it because it wasn't bright enough, and didn't reach to where it was needed. Same with the tool rests that came with the grinder....

You don't really 'need' more than the 180 grit CBN wheel. Me, I have to experiment..... If you don't want buy a second CBN wheel, then I would keep a coarse, like 36 grit wheel handy for shaping. As for honing, or stropping, I really like my Tormek for that. A piece of leather will work with some polishing compound on it. Even some MDF with the honing compound would work for the skew. I generally don't have much luck with the diamond cards or stones. Some of the honing pastes can go up to 16000 grit.

robo hippy
 
I'm going to start our with one CBN and one stone, may go to the second CBN. Paper wheel hones work as good as leather, I've been honing knives with a paper wheel for years and actually shaped one to fit inside all of the chisel flutes. Put a little rouge on the spinning wheel, couple of passes and you have a razor edge. You can see yourself in the metal next to the edge. I just can't justify the cost of a Tormek or even a knock-off when I've already got the paper wheel setup.
 
For the CBN wheels, I really recommend the self-aligning washers that Woodturners Wonders sells, sometimes included in the purchase of the wheels. It takes all of the guesswork out of balancing, not that CBN wheels need a lot of balancing.
Nevertheless, they really do the trick!
 
I have 7 CBN wheels on 4 different grinders and every one runs perfectly true with the washers that came with the grinders.
 
Have 4 WW CBNs, 60, 180, 350 and 600.
60 for reshaping (that one BITES!)
180 for scrapers and minor adjustments
350 for resharpening gouges
600 for knives and flatwork tools.

If only one, go for 180
If two, then 180 and 350/400.
 
Lars Hansen said:
Have 4 WW CBNs, 60, 180, 350 and 600.
60 for reshaping (that one BITES!)
180 for scrapers and minor adjustments
350 for resharpening gouges
600 for knives and flatwork tools.

If only one, go for 180
If two, then 180 and 350/400.
Click to expand...
Same here Lars - and I agree. the 180 is the one that gets much more use than all the others.
 
Tom De Winter said:
I have the 1/2 HP Rikon with a 600 (that I use all the time) and a 180 that I seldom use.
It is slow to spin up but giving it a spin by hand before hitting the switch helps and lessons the starting current.
Click to expand...
I too have the 1/2 HP slow speed Rikon with a 350 (that I use most of the time) and an 80 (used for mostly reshaping). Like Tom said, it is a tad slow to spin up but, once I turn it on, I usually just leave it running until I'm done with the project. It makes it all the more convenient to just pop over to grinder that's beside me and put fresh edge on my gouge. It helps me fight the urge to push my gouges further than I should before resharpening.
 
I use a 1HP Rikon grinder fitted w/ self-aligning washers, 180 and 600 grit mega square wheels. I use the 600 for gouges and the coarser 180 for scrapers, NRS, and skews. I simply went w/ Ken's Rizza's recommended grits and have been very pleased. I have swapped back and forth between the wheels for gouges but settled on this. I typically hone my NRS after removing any burr left after using it some following sharpening on the grinder upside down.

I am considering a coarse grit CBN wheel for shaping tools. 60 or 80 grit for that?

Also, what grit do you guys like best for HSS hollowing bits?
 
I bought the 180 and the 350 grit. I find the 350 is too high of a grit for general use. I should have gotten an 80 instead. I went back to the sorby proedge for sharpening, as it is easier to use anyway.
 
If I have serious shaping to do, I have a Jet belt sander with a 34 grit belt on it. Dave Schweitzer used to have a 10 inch Jet high speed grinder with a 60 grit on it for shaping his tools. Don't know if I would consider one for my shop or not. Just a bit too coarse for anything but shaping. I really do like the 600 grit when I need it for punky woods.

robo hippy
 
Hope you guys don't mind a different question concerning CBN wheels. I'm ready to order my first CBN wheel, but need one more bit of information. I have already made up my mind to buy the 180 grit wheel. I see some of you guys have a 1" wide wheel and some have purchased something called the Mega square wheel that I think is 1 1/2" wide. I have also pretty well made up my mind to buy the Vector Fixture for the Michelson Grind. My question is can you do the complete rotation needed on a 1" wide wheel or does one find themselves occasionally falling off the edge therefore the 1 1/2" is needed? I have not used any sharpening jig and don't even know if you can fall off the edge, just letting my mind explore all possible issues. Appreciate your help...by the way, I do have vibration in one or both Rikon wheels on the new grinder, kind of strange, it spins up smooth but when it is winding down I guess it has more time at each RPM so whatever speed the vibration is at it's worst, it shows up then.
 
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I think that the only reason some make the 1 inch wheels is that they are worried about liability issue with the wheel guards off. Main safety issue with the CBN wheels is inhaling metal dust, and yes, it will float around the shop like the wood dust does. I will never go back to 1 inch wheels. Main reason is that I have never run off the edge of a 1 1/2 inch wide wheel. Hate those grooves in the wings of my gouges.... Probably a very minor issue with platform sharpening, which is what I do, but more of an issue with the jigs...

robo hippy
 
I have 1" wheels as I wanted to keep the mass as low as possible for the 1/2 hp grinder I have. About once every 3-5 turning sessions, I'll fail to pay adequate attention and slip off the edge once. Nothing disastrous happens.
 
Bought my wheels at WW for the same reason as Dean. Much less mass for my rather weak grinder motors. Worked with steel wheels for 6 years first, but the alu ones work just as well.
Wouldn't miss the full width of the MegaSquares, though!
 
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