Finer CBN grits -- useful for lathe work?

[Dave Mount]

A year and a half ago I bought my first CBN wheel (180 grit) for sharpening lathe tools (Norton 80 grit blue wheels before), and 6 months ago I replaced my old POS Delta 8" grinder with the 1 hp Rikon half speed. What a difference! To anyone contemplating this upgrade, I cannot recommend it highly enough. Not everyone is fortunate enough to have the resources to do this, but if you can, do it, you will not regret it.

I originally bought the 180 grit as it seemed to be the "general purpose" single grit of choice. I have mostly Thompson tools, and right now I use tools right off the wheel for general wood removal, and for fine or finish work, I touch up the bevel with a diamond paddle hone and a swipe with a conical diamond hone on the flute side. I did some searching of the forum archives in regard to CBN grits and it seemed like early on in the CBN adoption phase (circa 2012) everyone was saying why would you need anything finer than 180 grit, but more recently there was more mention of using finer grits. With the smoothness and control the new grinder setup has, it seems to me like a finer grit could allow less steel removal and a finer edge, but then I've never used one.

Just trolling for thoughts on this, and if a finer grit is considered useful, which one to add to a 180 wheel -- 600?

Best,

Dave

[John K Jordan]

Dave,

I'm one who has written often about the finer grits. I've had a variety of grits and I use them for different purposes. That doesn't say I don't find a particular grit unsuitable for a particular use but I do find some more suitable.

My current wheels and previous wheels, 8" wheels on 1/2 speed grinders unless otherwise noted:
60 grit new today - wow does it remove the metal!
80 grit - used for 5 years for heavy shaping, still works but is showing the wear. I replaced it with the 60 grit today.
180 grit - used for a while but quit using it in favor of the 600. I removed little-used 180 and will probably give it away.
320 grit - gave a fairly smooth grind but frankly was too close in results to the 180 so I gave it to a children's turning program.
600 grit - my favorite for sharpening gouges, skews, and scrapers. I use it with both wolverine and Tormek jigs.
600 grit - 10" wheel on a very slow speed Tormek. Worked well but didn't make a smooth enough grind to suit me. I gave it away when I got the 1200 grit wheel.
1200 grit - 10" wheel on a very slow speed Tormek. I first used a 600 grit here but like the 1200 better. I use it for all of my spindle gouges, which I then hone to a polished edge. This lets me cut cleaner, especially on small spindles with hard woods. Some pieces don't need any sanding if my hand is steady enough that day. BTW, a fine wheel on a Tormek is an exercise in frustration for shaping a tool. It will work if you have enough extra years do dedicate.

As all most everything in turning, what you turn, how you work, and your skill level can make a difference. Some people mostly turn big, soft, green wood and are happy with a coarser grind on their bowl gouges. Some use the burr from the grinder on their scrapers and negative rake scrapers and are happy with a coarser wheel that leaves a significant burr. I prefer to turn smaller and sometimes more detailed things strictly from dry wood and preferably from hard, smooth-grained wood, the harder the better. I hone the grinder burr off all scrapers and use a burnisher to raise much smoother and longer-lasting burrs on scrapers, especially negative-rake scrapers.

Another thing, CBN wheels are made in aluminum or steel, different widths, with curved or square in profile with cornered edges, and with or without grit down the sides. I bought one with the radiused edges and didn't like it, however it would be useful to those who sharpen the bits of hollowing tools that can't be removed from the shaft. I buy only CBN wheels with cornered edges and with 1" of grit down the flat sides. This gives me more flexibility in grinding special tools. The last two wheels are Mega Square wheels with a full 1.5" width. I buy wheels from Ken Rizza at Woodturners Wonders because his prices are reasonable, he is fair and honest in his dealings, because he carries high-quallty aluminum wheels, because he carries the spherical washer sets which can eliminate certain problems, and because I bought my first wheels from him and have found no reason to change. (No affiliation, just a customer from off the street.)

BTW I use the diamond paddle hones (extra fine Ez Lap) and the conical hones exactly as you mention. I also use lapping/polishing compound rubbed on a piece of MDF to hole the very edge of my skew chisels to a razor sharp edge. If you don't use skews I strongly suggest learning them.

JKJ

A year and a half ago I bought my first CBN wheel (180 grit) for sharpening lathe tools (Norton 80 grit blue wheels before), and 6 months ago I replaced my old POS Delta 8" grinder with the 1 hp Rikon half speed. What a difference! To anyone contemplating this upgrade, I cannot recommend it highly enough. Not everyone is fortunate enough to have the resources to do this, but if you can, do it, you will not regret it.

I originally bought the 180 grit as it seemed to be the "general purpose" single grit of choice. I have mostly Thompson tools, and right now I use tools right off the wheel for general wood removal, and for fine or finish work, I touch up the bevel with a diamond paddle hone and a swipe with a conical diamond hone on the flute side. I did some searching of the forum archives in regard to CBN grits and it seemed like early on in the CBN adoption phase (circa 2012) everyone was saying why would you need anything finer than 180 grit, but more recently there was more mention of using finer grits. With the smoothness and control the new grinder setup has, it seems to me like a finer grit could allow less steel removal and a finer edge, but then I've never used one.

Just trolling for thoughts on this, and if a finer grit is considered useful, which one to add to a 180 wheel -- 600?

Best,

Dave

[roger wiegand]

I use a 180 grit wheel for sharpening, but hone with a 600 grit diamond slipstone dozens of times between sharpenings. I could use a finer wheel, but going to the grinder and fooling with the jigs would take longer and be more distracting from the turning than grabbing the slipstone out of my back pocket. It's not uncommon for me to turn much of the day without returning to the grinder.

Before my current addiction to honing I contemplated a second CBN wheel for quite a while. I ended up buying a second 180 grit wheel so that I could keep one set up with the Varigrind for my bowl gouge and the other with a platform for most everything else. I am thinking about adding another grinder some day with a much coarser wheel for reshaping tools as well as an AlOx wheel for sharpening softer steels (like my lawn mower blades).

The grind off the 180 wheel hones to a sharp edge with just a few strokes, so I haven't felt any need to go for a finer grit as a starting point.

[John K Jordan]

I use a 180 grit wheel for sharpening, but hone with a 600 grit diamond slipstone dozens of times between sharpenings. I could use a finer wheel, but going to the grinder and fooling with the jigs would take longer and be more distracting from the turning than grabbing the slipstone out of my back pocket. It's not uncommon for me to turn much of the day without returning to the grinder.

I notice a decrease in performance for delicate work the more times I hone a flat on spindle gouges and skew chisels. The flat changes the bevel angle of a hollow grind. But again, things in turning depend largely on what you turn and how. For the big bowl gouges it doesn't seem to make much difference. Almost anything will work.

For spindle gouges, to avoid the inefficiency of interrupting the turning to stop and setting up the Tormek jig I use another method. I keep six Thompson spindle gouges with identical grinds. When one gets dull I put it aside and put a new one in the handle and keep turning. When they are all dull I set up the jig once (takes about 30 seconds) and sharpen all six, just a few seconds for each successive gouge. I use a 1200 grit CBN wheel for the spindle gouges.

I keep multiple sharp skew chisels as well. I have a little jig I made to set the grinding platform to the perfect angle the first time and sharpen the skews by hand on a 600 grit CBN. This is very quick.

JKJ

[Reed Gray]

Well, some what different opinion than John's. I am primarily a bowl turner. For 90%+ of what I turn, the 180 is fine. For softer and more tear out prone woods, then I like the 600 grit edge, and I don't hone my gouges. For me, the 180 grit wheel leaves a more useful edge in that it cuts longer than the 600 grit edge before you need to go back to the wheel. I do have a 1000 grit wheel, which I need to use more. I prefer it for my skew chisels, and yes, I do actually use them once in a while. They still need to be taken to the honing wheel on my Tormek. I have tried the honing paddles on my bowl gouges, and on my skews and they just didn't seem to work as well as the 1000 grit wheel and then the trip to the Tormek. Life expectancy for the CBN wheels is in the 5 year range for production work. I also like the square edged wheels. I do have a set of the radius edge wheels. I don't have the side grind on my wheels, other than the 1000 grit wheel. I also agree with John about the 320 grit not being enough of a step up from the 180 to be worth the effort.

And Dave, I agree with going with the 1 hp grinder, or I have 2 Baldor grinders which are 3/4 hp, but have the same amount of power as the Rikon, but they cost what you can buy 3 of the Rikon grinders for. When I got my first 1 hp Rikon, first thing I did was remove the light they had on it, not bright enough, and it didn't reach to where it was needed. I took the rubber feet off so I could bolt it to plywood for ease of transportation. On my first one, I had to grind off 2 of the feet, cross corner from each other to get the grinder to sit flat, 1/16 off of each one. I got a second one about 2 years later and that base was fine right out of the box, but the light still came off. I did keep the grinder side part of the wheel guard on. I probably should have pounded the threaded screw holes flat so I wouldn't have had to ship the wheel farther off of the main body of the grinder.

robo hippy

[roger wiegand]

You make a good point John-- I have sometimes noticed that my skew did seem to work better after regrinding, I'm not experienced enough to have generated an Aha! moment from that sporadic observation, but now that you've said it I can see that it might be true, and will look for it.

The only thing better than having six identical gouges ready to go would be to have an apprentice sharpening them for you while you work. I'll need to push my sales up into the triple digits of dollars if I want to go that route! (related to the joke about the virus having put all the banjo players out of work, resulting in tens of dollars of damage to the economy)

[Steve Mathews]

I too would like to try one of the finer grit CBN wheels but have a problem finding a 600 grit with a 1" arbor. D-Way has them but they don't have the 1" flat along the sides. Anyone know of another good source for these?

[Steve Eure]

Steve, have you tried WoodTurners Wonders? They have a large selection of CBN wheels with all sorts of sizes. I don't know about the one inch arbor though. Wouldn't hurt to give them a call.

[Steve Mathews]

Steve, have you tried WoodTurners Wonders? They have a large selection of CBN wheels with all sorts of sizes. I don't know about the one inch arbor though. Wouldn't hurt to give them a call.

I sent a message to WoodTurners Wonders asking if a 1" is available but haven't received a response back yet. Their website only shows 5/8" and 3/4" arbor sizes.

[John K Jordan]

I sent a message to WoodTurners Wonders asking if a 1" is available but haven't received a response back yet. Their website only shows 5/8" and 3/4" arbor sizes.

Maybe call and ask to talk with Ken. Several times I've ordered wheels and honing plates he didn't advertise or carry and he had them made on special order for the same price. The only downside was I had to wait a few weeks but the older I get the more patience I seem to have.

If you call him tell him I said "hi" and the two mega square wheels are fantastic.

JKJ

[Reed Gray]

I am starting to wonder if I need another grinder and another set of wheels for that side grind option...

robo hippy

[Steve Mathews]

Maybe call and ask to talk with Ken. Several times I've ordered wheels and honing plates he didn't advertise or carry and he had them made on special order for the same price. The only downside was I had to wait a few weeks but the older I get the more patience I seem to have.

If you call him tell him I said "hi" and the two mega square wheels are fantastic.

JKJ

I called Ken this morning and ordered an 8" Mega Square CBN wheel in 600 grit. He will bore the hole out to 1" for the same price. I also passed along your message to him. My plan is to remove the 80 grit wheel now on one side of my grinder and store it for rough work only. The 180 grit wheel will remain for duty I'm not sure of yet. It'll be interesting to see how the 600 grit wheel performs.

[Dave Mount]

Please report back with your opinions of the 600.