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Some questions concerning CBN sharpening

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Forum topic by Jack Lewis posted 07-19-2017 07:23 PM 1446 views 0 times favorited 10 replies Add to Favorites Watch
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Jack Lewis

208 posts in 913 days


07-19-2017 07:23 PM

1. Is there any advantage to a grit finer than an 180 wheel?
2. Should a bowl gouge be sharpened with an 80 grit wheel to leave a burr?
3. If different grit wheels are used , is the final bevel required to be exactly the same as the first grind? My question here is; Can the sharpening jig be adjusted accurately enough when changing wheels?

Come on guys, share your thoughts and experiences.

-- "Now we are getting no where, thanks to me"


10 replies so far

View TheDane's profile

TheDane

5328 posts in 3498 days


#1 posted 07-19-2017 08:35 PM

1. Is there any advantage to a grit finer than an 180 wheel?
Not in my opinion. I have an 80-grit CBN for shaping and 180-grit CBN for sharpening.

2. Should a bowl gouge be sharpened with an 80 grit wheel to leave a burr?
Not necessary. If you put a burr on a bowl gouge, chances are it will get knocked off after a couple of cutting revolutions of the wood. I sharpen my gouges on the 180-grit wheel.

3. If different grit wheels are used , is the final bevel required to be exactly the same as the first grind? My question here is; Can the sharpening jig be adjusted accurately enough when changing wheels?
Not sure I completely understand the question. I use Raptor jigs (from Craft Supplies) on both the 80 and 180 wheels so my grinds are as close to identical as I can get them.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View Wildwood's profile

Wildwood

2186 posts in 1970 days


#2 posted 07-20-2017 01:59 PM

If watch D-way video’s says he cannot tell the difference between 80 or 120 grit cbn wheels he sells.

I have been using 80 grit AL wheels to sharpen/ resharpen my tools as long as can remember. Think an 80 grit cbn wheels will serve you well. I don’t worry about the burr like Jerry said only last a secon or two. Not sure where 80 grit falls on cbn wheels but most AL manufacturer classiy 80 grit as fine so would thing same for cbn wheels. My experience with 100 & 120 grit AL wheels took me longer to sharpen and tended to blue my tools.

Benefit of a jig is getting consistenacy at the grinder everytime. Big benefit of cbn wheels they don’t wear like AL oxide wheels so once you get your jig set you are good to go.

-- Bill

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WWhite

1 post in 145 days


#3 posted 07-20-2017 03:12 PM

My first post here, and I am certainly no expert regarding anything. I would like to add my experience with CBN wheels, however.

I used to ‘share’ a sharpening system with a friend. When the stone wheel shattered while he was using it, we decided to upgrade to CBN wheels.

I purchased a grinder and CBN wheels from Ken Rizza at Woodturnerswonders.com It was his recommendation that I purchase a 350 grit and 80 grit wheel. I must say I couldn’t be happier. Great product/great vendor.

I have the Raptor jigs and the One Way with the VariGrind. If (and that is a big “if”) I need to reshape a tool, I use the 80 grit wheel. All other sharpening uses the 350 grit wheel, and I can sharpen everything in my limited tool set of 10 tools in 10-15 minutes. As for touching a tool up, doing that on, for example, my large round scraper takes less than a minute on the 350 grit wheel and it is razor sharp.

Again, no expert; just a very satisfied user.

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GordonPrill

1 post in 432 days


#4 posted 08-12-2017 02:58 AM

My first cbn wheel was a 180 grit. I loved it compared to the AO wheel I was using. After about a year I wanted to see if I could achieve a better edge and save tool steel. I added a 320 grit wheel about 6 months ago and really like it. I get an edge just as sharp with 2 passes, and I feel I’m saving tool steel. I still use the 180 for roughing gouge and others and use the 320 for bowl and spindle gouges.

View Kelly's profile

Kelly

1821 posts in 2779 days


#5 posted 08-12-2017 04:32 AM

I have the 80 and 180 grit wheels. “Generally,” I only use the 80 for roughing in, then I go to the 180. That is so I eat less material than I would using the 80.

I should not that the problem of eating a lot of metal is less a problem for my system than all but a few here because my system is a four wheel pillow block system powered by a DC, variable speed motor, which I seldom crank up over a few hundred RPMs, since faster speeds aren’t necessary.

Essentially, having a finer wheel might be said to be akin to running at my lower speeds – less material removal. Of course, you, also, get a finer edge, which cannot hurt any.

As to the burr, I agree with Gerry, it would be gone after a few turns anyway. Often, I find myself cleaning off the burr, from the inside of the gouge using a diamond edge, to improve the cut. It seems to help me toward better edges.

View Bill7255's profile

Bill7255

412 posts in 2120 days


#6 posted 08-13-2017 12:27 AM

I just have the 180 grit. I bought mine several years ago and at the time I was told to only sharpen HSS or better as it would load up the wheel. Don’t know if that true, but I kept my white wheels for some of my homemade tools. I have the CBN on one side and white wheel on the other side and for shaping I use the 36 white wheel. The CBN wheel will be somewhat aggressive at first, but break in. I haven’t had the need to go to a higher grit.

-- Bill R

View bigJohninvegas's profile

bigJohninvegas

382 posts in 1297 days


#7 posted 08-21-2017 06:59 PM

Gerry is spot on. I still use a stone wheel for rough shaping, and a 180 cbn for finish work.
I too got my cbn from Ken Rizza at https://woodturnerswonders.com
I wish I had taken advantage of the two wheel special.

I have had the ongoing pleasure to learn from Jimmy Clewes.
And recently I have learned from him that a small 300 grit Machinist file will keep a tool sharp for a long time.
No need to go to the grinder every time you need to touch up an edge. I find myself using the cbn to sharpen, then the diamond file as the tool dulls. I will use the file 4 or 5 times easy, before returning to the cbn wheel. Gives me a great edge that last the same time as the wheel, takes less that a minute to do with no jig setup, and helps extend the life of the tool.
http://jimmyclewes.com/product/jimmy-clewes-james-barry-sharpening-woodturners-sharpening-kit/

Quick edit, while the machinist file does a good job, I may go back to the cbn for a touch up before making a finish cut on something delicate, or highly figured where it is prone to tear out.
And the only time I ever use the 80 grit wheel is to put a custom grind on a new tool. or maybe if I screw up and drop it, damage the cutting edge really bad. after that its always the 180 and the file.
Several here use the raptor jigs. they work well, and will give you a repetitive setup.

-- John

View Jim Jakosh's profile (online now)

Jim Jakosh

19768 posts in 2940 days


#8 posted 08-22-2017 12:23 AM

When I got hooked onto turning, my mentor told us to use 100 grit wheels and that is all I use. As for the last question, I use a fixture for holding the gouge that is not adjustable. My mentor also let us copy that sharpening jig and if I set the back block the same distance from the wheel on each wheel, the grind will be followed perfectly so I don’t waste any of the gouge steel with a change of contour. I really don’t like adjustable holding fixtures because a fixed one takes one variable out of the process.
Any time you vary the angle, the wheel grinds a different pattern and you may have to take off a lot to get it to grind to the edge. When I buy a new gouge, they seem to never be at my fingernail grind angle. I keep grinding them to match my contour and it stays like that forever more!

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View TheDane's profile

TheDane

5328 posts in 3498 days


#9 posted 08-22-2017 01:17 AM

My mentor also let us copy that sharpening jig …

Can you show us a picture of that jig?

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View Kelly's profile

Kelly

1821 posts in 2779 days


#10 posted 08-22-2017 01:31 AM

I, one hundred percent, agree with Jim on the issue of varying the angle. I have VERY EXPENSIVE knives and I take great care to avoid shifting the sharpening angle by even a degree, since failing to do so seems to put me back to where I started.

As to his mentor’s recommendations on wheel grits, I also agree, but only to the degree that there are a thousand roads that will get you to Rome, and this is one of them.

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