180 CBN Wheel - Would go higher grit

[David Metzman]

I recently got my first cbn wheel. it is 180 grit. It really takes the metal off. I think I would go with a higher number next time for turning tools if I was only getting one. Not sure if it mellows out after a bit.

On sharpening gouges and other sharp turning tools, do most people just go to the grinding wheel each time and that is it? In my case the new 180 CBN. Or 1) do you do some finishing afterwards? Do you touch up the sharpness by some other method before going to the wheel? Thanks

searches on the forum - I had only see the search box at the top of the page (that takes you to google). Just noticed the little search drop down in the upper middle right of the page - that should be more useful.

[Steve Schlumpf]

David, I have had my 180 grit CBN wheel since 2011 and can tell you that when you first start using it, it is aggressive. It will smooth out over a few months of using it and you will find that 180 is plenty smooth enough. I am sure everyone has their own way of doing things when it comes to sharpening - I just go to the grinder, touch up the edge, then go straight back to turning. I can see honing if you are making final cuts on a finial or something delicate but for the most part, the edge I get right off the CBN wheel works great as is.

[Reed Gray]

I never realized how much difference there is between a well broken in CBN wheel and a new one till last month. The old wheels were at least 6+ years old. I had my main grinder in a crate on the way to the Symposium in KC, and bought out the other grinder which had a new 80 and 180 grit wheel. It really surprised me how much faster the new wheels cut. I didn't like the edge from the 80 grit wheel at all, though it cut. With the old wheels, I couldn't tell much difference between the 80 and 180. On the old wheels, the edge is much more polished. How fast they break in depends on how much you use them. For me, when I was doing production turning, it was a matter of about 3 months, but I think the process goes on for a year or so before it pretty much comes to a stand still. The 180 grit edge is fine for about 90% of the turning you will ever do. No idea how the 320, or 400 grit wheels do. I do have a 600 and 1000 grit wheel, and they are great for fine finish cuts, but lousy for roughing edges because they go dull so quickly. Sharpen your scrapers on the 180 a number of times, that will help, and the burr from the 180 grit wheel is excellent for shear scraping and heavy bowl roughing.

robo hippy

[John K Jordan]

On sharpening gouges and other sharp turning tools, do most people just go to the grinding wheel each time and that is it? In my case the new 180 CBN. Or 1) do you do some finishing afterwards? Do you touch up the sharpness by some other method before going to the wheel?...

David,

My experience, with the understanding that most of my turning is spindles and fairly small things, almost always dry wood, and often hard exotics. I only rarely turn green wood bowls and hollow forms - those needs may be quite different.

My CBN wheels are 600 grit, 220 grit, and 80 grit on 1/2 speed bench grinders. I also use a 1200 grit 10" wheel on my Tormek.

On the bench grinders:
- 600 grit is perfect for hand-held sharpening of my skews, scrapers, parting tools, bedan, and bowl gouges,
- 220 grit is good for most shaping
- I use the 80 grit only occasionally, for reshaping heavy tools, especially scrapers - the least useful but it cuts very fast!

On the Tormek I had a 600 grit but it didn't give me the fine edge I wanted for my spindle gouges. The 1200 grit is much closer. I want my spindle gouges with razor edges, honed and preferably polished.

I do not use a tool with a burr from grinding. After sharpening I hone ALL gouges, scrapers, skews on either the rotating leather wheels on the Tormek or a leather strop, both having some Tormek honing compound applied. I use the wheels on both sides of the edge, inside and outside the gouges. This knocks off any burr or fine wire edge and gently polishes the cutting edge. For spindle gouges and skews for small work in hard, fine-grained wood (cocobolo, ebony, etc.) I like to spend more time on the honing wheel which gives nearly a mirror polish on the edge resulting in an extremely smooth surface. For scrapers, I don't use the ground burr but turn up a cutting burr with a carbide burnisher.

If I had just one CBN wheel it would probably be a 220 grit, sharp enough for most scrapers and other tools for general turning. The edge directly from a 220 wheel is works fine for bowl gouges for turning green bowls.

As Reed mentions, all these CBN wheels get less aggressive with use. I get the feeling the coarser wheels "break in" more than the fine wheels. I didn't notice much difference on the 600 grit after a lot of use. But I don't get much turning time so from Sir Reed's experience it might take a long time before I see a difference.

JKJ

[David Metzman]

Thanks for the very useful info - David

[Richard Dooling]

I've had my 180 grit for some months and it is much less aggressive than when new.

I use a very fine diamond hone between trips to the wheel. Just as with a chisel or plane iron, a hollow grind gives two points to register the hone against the cutting edge and the heel. I often use the slot in my bandsaw table to steady the tool while honing.

[Steve Mellott]

I only use the 180 grit wheel. If you are only sharpening (and not reshaping), you only need to touch the tool to the wheel 2-4 times. With this light touch, there is no need to grind away a lot of the tool.

[David M Peters]

I have two CBN wheels, 80 and 220 (4-in-1 from Mr. Rizza). I'm very happy with this combination, the 220 leaves a nice surface and isn't slow to cut at all. I deviated from the usual 80/180 combo just to give a (theoretically) finer grind.

However if you get into the habit of hand-honing while turning I don't think the exact grit of your wheel matters much anyway! I bet there was a lot less analysis paralysis back when everyone simply used gray 80-grit wheels :-)

[John K Jordan]

R

I... bet there was a lot less analysis paralysis back when everyone simply used gray 80-grit wheels :-)

Ha, there was probably just as much but with a different slant!

Some dodn't sharpen on 80 grot wheels. I used finer Norton wheels on a std bench grinder at first then quickly went to a Tormek. The type of turning might be a major factor. Since I liked to turn smaller things from mostly hard, fine grained exotics the edge from the grinder was important on my skews and spindle gouges. The best edge was nearly a mirror polish (just like a carving gouge). Any scratches on the tool are transferred to the wood so a polished edge could make cuts (on small work) that needed no sanding or often just 800 or maybe 600. When turning larger bowls, especially green, the edge was not nearly as important and right off an 80 grit wheel was fine.

I do hone and strop most tools on leather with a compound added, and hone between sharpenings with the blue extra fine Eze-lap diamond paddle hones.

I resisted going to CBN for a long time after it seemed all the better turners had switched but finally broke down. For me, CBN has simplified sharpening by eliminating the balancing and dressing and making much finer grit wheels available. I think I mentioned earlier that I replaced the water wheel on the Tormek with a 1200 grit CBN. With all the jigs and rests available today professional-level sharpening has never been more accessable. I'd hate to go back!

JKJ