2nd CBN grit? 1st is 180.

[Brian Kent]

I currently have an 8" D-Way CBN - 180 grit on my 6" grinder.

If I upgrade this summer to the Rikon 1hp 8" slow-speed, then I can add a second CBN wheel.
I am set up for gouges with the Wolverine setup on one side and the platform on the other for scrapers.
I do not like to switch them, so the 2nd wheel will always be for the platform / scraper side.

So my question is: For scrapers would you recommend another 180 grit, an 80 grit, or one of the super-fines you have used.

[John Grace]

Brian...Look for the thread I started recently on WTR titled CBN Sourcing. It has some relevant information there to your question above. Also, I believe there's a thread here on Negative Rake Scrapers that touches on what you're asking as well. Not to speak for him, but Robo Hippy has done some experimenting on varying grits and I believe in one of his posts he states that at 600 grit, the burrs on his scrapers becomes too fragile. Apparently, he prefers the higher grits for high shear angle scraping but a lower grit for perpendicular scraping. Read the the threads for yourself in case I misrepresented anything but I believe that's the gist of it. THANKS...John

[Brian Kent]

Thank you John. That advice narrows my range. The second wheel for scrapers could be 80, 180, up to 320.

[Joe Bradshaw]

Brian, I have the 80 grit on one side for scrapers. The 180 is on the other side for gouges and parting tools.
Joe

[Roger Chandler]

Brian, I have 80 grit CBN on one side and 180 grit CBN on the other side of my grinder. I agree with Joe in his comments above that the 180 is great for gouges, parting tools, skews........the 80 grit I also use for shaping a profile and for most of my scrapers. The burr off the 80 grit on scrapers is pretty effective on smoothing any ripples left or helping with shear cuts to deal with tear out or tool marks.

I think there has been a lot of folks going too fine on CBN grits lately. One world famous turner[Raffan]mentioned at a demo I attended, that he has used 46 grit wheel for decades.....said it did a great job for him. Not sure what he uses lately now that CBN has taken hold, but I would think that the majority of users of CBN wheels likely go with 80 and 180 grits.......they will cover most anything. If one wants a finer edge, then honing comes into play .....on the skew especially.

I personally would not go over 220 grit, possibly 320 grit, if I were concerned about a really fine edge...once that 180 gets broken in, the edge and bevel are pretty polished as is, so not sure how much one helps themselves with anything over 220 grit.

[John K Jordan]

Brian, if you decide on a finer grit and are not in a hurry, I plan on selling or trading a practically new CBN wheel in a few weeks. I think it is 320 grit, I need to check. I decided to replace it with a 600 grit with square corners. I have the 600 in hand but unfortunately I won't have time to deal with listing the other one until after May 5. I plan to list it on the Classifieds at a good price.

I think this is it:
http://woodturnerswonders.com/collections/4-in-1-cbn-wheels/products/cbn-wheel

JKJ

[Reed Gray]

I just got back from a Saw Dust session up in Salem Oregon. Terry Gerros is the host, former president, and principal instigator behind the Oregon Woodturning Symposium. I took up my grinder with the 600 and 1000 grit wheels on it since the session was on gouges, and bowls. Terry had a nice soft piece of big leaf maple on his lathe to shape and show tool technique. I took a gouge that was sharpened on the 1000 grit wheel, took about a 1 inch long pass and had him look. After looking at the difference, he kept asking 'Are you sure you don't want to leave that grinder here?' It pretty much eliminated the tear out on the bowl. We have all tried to turn a piece that was 'too soft', and this fine edge really cleaned it up. I finally got to take my grinder home after he sharpened all of his tools on it.... 'I don't know if I should thank you for bringing this up today or not....'

So, what do you need??? Well for scraper burrs, there is no real difference in burr edges on scrapers for heavy roughing between the 80 or 180 grit wheels, and same for shear cuts on good sound wood, or wood with no or little figuring. The 600 grit, on both gouges and scrapes, well, the 1000 as well, leave edges that are excellent for fine finish cuts and cleaning up things on difficult woods, but not practical for heavy roughing as they just don't keep the edge as long as the coarser grits. I need to swap back and forth between 600 and 1000 a bunch of times to see if there is any significant difference in those edges for cleaner cuts. High shear angle still plays into the formula, but the edge from the wheel is another player in the game. I can't see that 220 grit would be better or not, and same with 320, and I haven't tried either of them out. Don't think I will. With the hand honing, I never saw enough improvement to consider it worth the effort. Perhaps I was doing it wrong. With these wheels, of the same grits as the hones, there is a big improvement. You could get away with an 180 and 600 if you are going for only 2.

We also tried some of that blue honing compound (can't remember the name, but for diamond hones) on one of Terry's wheels and it seems to have improved the cutting action. Now I have to get some of that....

robo hippy

[Prashun Patel]

resurrecting this thread. Thanks Brian. I am thinking the exact same question. Am going for an 80... Thanks guys!

[John Keeton]

Prashun, check this thread - https://sawmillcreek.org/showthread.php?260762-%94owed%94-to-JKJ-and-Reed

I am really impressed with the 600 wheel and glad I did not get the 80 grit like I thought about doing.

[John K Jordan]

Prashun, check this thread - https://sawmillcreek.org/showthread.php?260762-%94owed%94-to-JKJ-and-Reed

I am really impressed with the 600 wheel and glad I did not get the 80 grit like I thought about doing.

The 600 has turned out to be my favorite wheel for skews, bowl gouges, and scrapers. I do like the 80 grit for occasionally shaping or reshaping tools. Even the 80 grit took a while to remove large amounts of the 10V Thompson steel to shape a new 1-3/8" skew and these NRS, 80 to shape and 600 to sharpen:

377155

If starting over and had room for just one bench grinder I'd probably go with just the 80 and 600. But to be fair I rarely use the 80 compared to the 600. I suspect a coarse AlOx wheel would work fine for shaping and would be a lot cheaper. (If the conventional wheel was mounted on the same grinder as a CBN I suspect it would need to be balanced very well to keep slight vibration out of the CBN.)

JKJ

[Reed Gray]

I am at a point where I can not see how I got along with only one grinder. Some times I need to seriously shape new tools, or change profiles in some existing tools. For me, that requires a 36 grit belt on a 1 1/2 hp belt sander. 80 grit CBN is good for minor changes. 180 is my preferred wheel for 'general' use. 600 for fine finish cut edges. So is 1000... There seems to be no end to the vortex..

robo hippy

[John K Jordan]

... There seems to be no end to the vortex..


I am ashamed to admit I have a Tormek plus five bench grinders in the shop, some in another room, one in the garage at the house. This is after giving away two bench grinders in the last year or so. And I'm still looking for a second Tormek. Somebody stop me, please. What is the family going to DO with all this stuff when I kick the bucket?

377201

I'll have to try the 36 grit belt method.

JKJ

[Prashun Patel]

I was able to change my order from an 80 to a 600. I was originally going to put my flat tool rest on the 80 for scrapers, but I think I'll put varigrinds on the 180 and 600 and then keep the flat on the AOx wheel. Glad I found the thread.

Who am I kidding? I am sure I'll end up with that 80 and others over time anyway. :(

[David Delo]

I am ashamed to admit I have a Tormek plus five bench grinders in the shop, some in another room, one in the garage at the house. This is after giving away two bench grinders in the last year or so. And I'm still looking for a second Tormek. Somebody stop me, please. What is the family going to DO with all this stuff when I kick the bucket?

377201

I'll have to try the 36 grit belt method.

JKJ

John,

You have an extreme condition known as Reverse Mechanophobia.....................

Mechanophobia is the fear of machines. The phobia is often caused by traumatic experiences associated with
machines, like losing a finger or toe by a machine. Dangerous machines, such as shredder, grinder, and
chain saw, can cause injuries more easily and thus are more effective triggers of phobia.

Symptoms of mechanophobia include dizziness, increase in body temperature, rapid heartbeat, trembling,
panic attacks, and urge to flee. Mechanophobia can be treated by simply understanding the fears, especially
about the triggers, while learning new ways to cope with the fear.

[John K Jordan]

John,

You have an extreme condition known as Reverse Mechanophobia.....................

Mechanophobia is the fear of...
Symptoms of mechanophobia include...
Mechanophobia can be treated by ...


I think it might it's shopagoraphobia - fear of open space in the shop.
Or maybe inverse-ataxophobia.

You forgot to prescribe the treatment for the reverse mechana, er, what you said.
Oh, I know the treatment: add a wing on the shop. :)



JKJ