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CBN Advice?

Mark Hepburn

Mark Hepburn

Artist & Chef
Joined
Mar 26, 2014
Messages
1,622
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580
Location
Houma, Louisiana
So I have one of the Rikon slow speed grinders and currently it has a D-Way 180 CBN wheel and an 8" white AO wheel that's gotten a bit small and it's time to think about replacing it and I'm needing advice/opinions.

I only use the setup for my turning tools, and I'm wondering if I shouldn't put another CBN wheel on the other side, and if so, what grit, what profile, etc.

I use my Ellsworth grind gouges most of the time and have his jig, as well as a wolverine/vari grind and one of Robo's tools rests. The other tools I have are a few Thompson gouges, parting tool, detail gouges, smaller spindle gouges and some skews.

I'm leaning toward CBN just because of all the crud that the AO wheels throw off and because it maintains a fixed diameter, is balanced, isn't likely to blow off the grinder, and so on. But frankly I don't know if that's the wisest course so therefore, I'm asking. Will I, for some reason that I haven't anticipated, come to regret having another CBN wheel and should I go a different direction, and so on and so forth, etc. etc. etc.

Help a brother out, people!

Thanks,

Mark
 
Replace the AO with another.
Keep in mind that once you go all CBN, no more grinding of carbon steel tools or random items.
If you already have another grinder for random stuff.....well thats good.
I went all CBN and then found that I had to improvise for the things I would have ground without a second thought.
When the rikon's went on sale at woodcraft I bought one for utility work.
The CBN's don't throw dust, but do spray metal around the shop, especially if you have removed the shields.

Anyhow, my $.02
 
If money were no object,[SUP]1[/SUP] then I would definitely go for an 80 grit CBN wheel. Two good reasons are that you don't have the big mess caused by the aluminum oxide grit all over the shop as well as not having to contend with the hazardous superfine dust that hangs in the air forever. There is still the issue of metal particles, but I suspect that even that is reduced compared to using AO wheels so I would still continue to wear respiratory protection while sharpening.

I have been using Norton 3X wheels for several years and they are a huge improvement over the white wheels from the perspective of wear which also means that grit and dust are far less of a problem. However, they still throw out plenty of grit and dust. For a long time I have been thinking that I would wait until these 3X wheels were worn out before going to CBN, but lately I've been thinking that I really don't want to wait that long. And since I have now come to realize that money is no object[SUP]1[/SUP], there are no longer any obstacles to buying whatever I want... at least, in theory.

_________________________________________________________________________________________
[SUP]1[/SUP] Money certainly is no object if you don't have any. But, on the other hand, those who do have money are often heard saying that money is no object, so it is only logical to conclude that money is no object. QED
 
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Mark Wollschlager said:
Replace the AO with another.
Keep in mind that once you go all CBN, no more grinding of carbon steel tools or random items.
If you already have another grinder for random stuff.....well thats good.
I went all CBN and then found that I had to improvise for the things I would have ground without a second thought.
When the rikon's went on sale at woodcraft I bought one for utility work.
The CBN's don't throw dust, but do spray metal around the shop, especially if you have removed the shields.

Anyhow, my $.02
Click to expand...

Thanks Mark! That's one of the unintended consequences I was referring to. Maybe a 2nd grinder for a hundred bucks when they go on sale again. ..
 
I talked to one of the CBN providers and he said an occasional sharpening of Carbon steel tools won't hurt the CBN. Lots of use could clog it but if you follow it with sharpenings of HSS it usually cleans it. Can't say that's true of them all and I can't remember which guy gold me this. I plan to go to a course CBN wheel on one side once my White wheel gets too small.
 
So if I were to get the HF grinder to use for a while (and give to my son-in-law when I get a Baldor one day), and go CBN, what grit for the new wheel? And would a radius edge or one with side grind capability be something to consider?

One never knows where he will end up on the woodworking path, so I'm not sure that I'll never need those capabilities. I'm not an experienced user of the tool so dont' know if these are applications I should be actively considering. Given that the current cost of the wheels - including purchasing a HF grinder - is on par with what I paid for the first wheel, that's not too bad so I want to consider what I might need in the future for my turning tools.
 
I considered the fancy profiled wheel

Mark Hepburn said:
So if I were to get the HF grinder to use for a while (and give to my son-in-law when I get a Baldor one day), and go CBN, what grit for the new wheel? And would a radius edge or one with side grind capability be something to consider?

One never knows where he will end up on the woodworking path, so I'm not sure that I'll never need those capabilities. I'm not an experienced user of the tool so dont' know if these are applications I should be actively considering. Given that the current cost of the wheels - including purchasing a HF grinder - is on par with what I paid for the first wheel, that's not too bad so I want to consider what I might need in the future for my turning tools.
Click to expand...



Mark,

I considered the wheel with a radiused edge, side grinding capability, all kinds of features. Was all gung ho to get it. Then a little cyphering revealed that the part of the wheel that I use all of the time was only I think 3/4" wide. The radiused edges and such come at a cost. I have all kinds of sanders around and a few side grinders. I have an arbor to go in the lathe headstock. I can figure out a way to grind any occasional job and Robo's rest with or without some of the small cutter holders will let you sharpen small cutting inserts just fine. I decided I wanted the widest surface where I do way over 90% of my grinding and for the maybe 2-5% of unusual grinding I can always put something to use.

Another consideration is weight. The CBN wheels are all heavier than stone I believe but some are much heavier than others. So far I haven't read anywhere that the extra weight is really a plus in usage. Starting load on the motor has to be sharply increased with two heavy CBN wheels. This could be an issue with some of the lighter duty grinders.

My personal issue now is what grit to use solely for sharpening? Finer and finer grits are becoming available with the CBN wheels. Being a metal miser I want to take as little off as possible and I wind up honing my steel two or three times between sharpenings, seems like the finer the better on a wheel, . . . maybe. For my once in a blue moon reshaping I can always throw on an old white wheel or whatever I have laying around.

I don't know what your needs are but consider your personal needs, not somebody else's marketing. We have a lot of wheels on the market now and so far I haven't heard of any of them having issues. I think I want a wide flat eight inch wheel or two that is pretty light. Wouldn't mind the side grind feature but I wouldn't pay much extra or make many trade-offs to get it. Main thing comes to mind is I might do a better job of sharpening pencils with it.

Hu
 
I do have an article on my web site about CBN Wheels, and it also was in the issue 2 months ago in More Woodturning (Fred Holder sold it). I also put it up here some where, maybe 6 months ago. www.robohippy.net

Anyway, the short edition: You can grind softer steels on the CBN wheels, but they will load up. You generally can clean them off by sharpening a good heavy scraper on it. Dale Bonertz told a story about a turning friend of his who ruined a wheel by grinding the wrong type of steel on it, and totally loading it up. Packard Woodturning catalog has a 'cleaning' stick of hard aluminum oxide that can clean up a wheel as well. I did try cleaning mine up with a very hard wheel that I had, and it took the sludge off (my grinder is in the line of fire and I turn sloppy wet wood), and as near as I can tell, did nothing to reduce the cutting ability. All that being said, the old "an ounce of prevention is worth a pound of cure" is good advice. Once in a while won't hurt them, but don't make a habit of doing it all the time. Having a separate grinder for soft steel can be handy, and you don't need much for lawn mower blades. Bench chisels are fine on CBN wheels.

I don't have any use for the radius edges. I can see them being handy for the hollowing bits which are sharpened in a jig. It is easier to push it around the rounded edge than it is to pivot them out to the side, and I think it gives a better side grind. Other than that, I can see no use for it. I actually prefer the square edge. I prefer the 1 1/2 inch wide wheels. With the 1 inch wide wheels, I would from time to time, go off the edge when sharpening gouges, and put a big divot in the wings. Free hand or with jibs, no difference. I have never done that with the 1 1/2 inch wide wheels. The side grind part, well, I can't think of a single use for that. I asked Dave Schweitzer about that, and he said that the carvers liked it. Perhaps the only other thing is that now, Ken Rizza of Woodturning Wonders has aluminum hubbed wheels. They are much lighter than the steel hubs, which could add to the life of smaller grinders, like the 1/2 hp Rikon. If you are going to have 2 wheels, then both an 80 and 180 grit should do just about everything. CBN wheels are far better than any other type of wheel out there.

robo hippy
 
All the sharpening that I have ever done has been on flat face stones and I can't conceive of any valid reason for a radiused edge. I have heard some reasons that don't seem to hold water, at least not for me. Also, I'm with Hu when he said that a radiused wheel just means a narrower useful wheel.

As far as grit is concerned, some of my fellow WNT club members have 80 grit and 180 grit wheels on their grinders. If it were possible for grinders to have a third wheel then the new 400 grit seems to be a very nice choice for things like skews.

One nice thing about my grinder is that the shroud is large enough that I can leave the shroud on. It also has a built-in dust collection port.
 
Mark Hepburn said:
That is a great suggestion, Bill. Tha t would be the go to grinder for the miscellaneous junk tools. Nod for not much more than going to a movie...

Best of both worlds.
Click to expand...

BTW Mark,

I won't say that HF exaggerates a bit when it comes to horsepower, but just so that you know:

Voltage = 120
Current = 2 Amps
Typical efficiency of low cost two pole AC induction motor = 70% (on a good day, probably 60% if it is from HF)
Conversion from watts to horsepower: 1 HP = 746 watts

So, being extra generous to HF and assuming 70% efficiency, we have:

120 X 2 X .7 / 746 = .225 HP

So, tossing in a little more lagniappe for HF, we can say that the advertised half horse motor is, at best, a quarter horse. That is still good enough for lawnmower blades.
​

I wouldn't be too surprised if the Rikon grinder wasn't quite as powerful as stated either although better than the HF.

​
 
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I grind all kinds of things on my CBN wheels, screws, plate, I don't care too much, it's a grinder.

Maybe they are loading up, but I haven't noticed.

If you want to come up to Plano, I will give you an old Woodcraft 1700RPM grinder.

But I would go ahead and buy another CBN wheel, 80 grit for shaping and negative rake scrapers. As mentioned there are aluminum CBMs for the low torque grinders, but I haven't tried them.
 
The wide side grind is for skews. This will give you a flat grind for it which is much more user friendly than the hollow grind we get on the front of the wheel. Also some carving tools are better sharpened on a flat surface. Ken has a picture of using the side grind on a skew in some of his newsletters and probably on the website to show skew sharpening.
 
Gerald Lawrence said:
The wide side grind is for skews. This will give you a flat grind for it which is much more user friendly than the hollow grind we get on the front of the wheel. Also some carving tools are better sharpened on a flat surface. Ken has a picture of using the side grind on a skew in some of his newsletters and probably on the website to show skew sharpening.
Click to expand...

Didn't know who your Ken reference was so I did some Googling and finally found it (after getting sidetracked on some other Ken's and different sorts of CBN's).

Is this it? http://woodturnerswonders.com/collections/cbn-wheels

I noticed that Jeff Gilfor just put in a review for their Tormek wheel. That is something that I might be interested in.
 
Bill Boehme said:
Didn't know who your Ken reference was so I did some Googling and finally found it (after getting sidetracked on some other Ken's and different sorts of CBN's).

Is this it? http://woodturnerswonders.com/collections/cbn-wheels

I noticed that Jeff Gilfor just put in a review for their Tormek wheel. That is something that I might be interested in.
Click to expand...

Sorry I did not give the web site as he had been mentioned by Robo. Yes that is him and he will do club purchases and by getting enough (mixed order allowed) in total number of wheels the club can get the different lights and for a large order 13-20 wheels can get a free wheel. We got a Beacon Lamp and it give a good light.
 
The main tool I grind that loads the wheel a bit is my Big Ugly, which has a 1 by 3 inch piece of tantung silver soldered on to a piece of 1/4 by 1 inch cold rolled steel. You can feel and hear a bump or ticking when grinding. I tried some aluminum once, and it left a silver line around the wheel. Comes off easily with a big scraper.

robo hippy
 
Mark,

Before you buy a grinder from HF, check the reviews. I spent some time doing that yesterday and wasn't very impressed with their ¾ HP 8" grinder and the ½ HP 6" grinder wasn't a great deal better. It is interesting because it seemed like people either loved or hated the grinders. There were some comments that I saw in both the good and bad reviews: wimpy torque and flimsy tool rest. Since woodturners for the most part don't care about the toolrest that comes with the grinder and usually get an aftermarket rest that complaint doesn't matter much. Some of the comments about power indicated a problem with the start capacitor. One reviewer stated that he replaced the 12 μF capacitor with a 30 μF part and the grinder started and ran much better. Since the start capacitor has nothing to do with mechanical torque output once the motor is up to speed, it is likely that some of these grinders never get going fast enough for the centrifugal switch to disengage the start winding circuit. A couple reviews stated that the grinder was running so slow that they could be stopped just by grabbing the grinding wheel. Now, that is really weak (and maybe foolhardy as well). If there is a HF near you then returning a bad grinder isn't such a big deal, but if you buy it online then the possible need to return it is something to consider.
 
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I sharpen all my ornament hollowing tools and all of my HSS hollowing cutters using the radius edge and love it. It is so much easier than trying to swing the tool to create what sort of looks like a bowl gouge grind without the flute. I learned to sharpen on 3/4" wide stones so I don't have a problems with the less wide wheels. Won't say that I've never run off the edge. You do have to be careful with any grinder.
 

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I sharpen all my ornament hollowing tools and all of my HSS hollowing cutters using the radius edge and love it. It is so much easier than trying to swing the tool to create what sort of looks like a bowl gouge grind without the flute. I learned to sharpen on 3/4" wide stones so I don't have a problems with the less wide wheels. Won't say that I've never run off the edge. You do have to be careful with any grinder. About 2 1/2 minutes into this video I show that technique for sharpening.
https://www.youtube.com/watch?v=M9G16ylEZHQ
 
I am with Bill on this one. I have a second grinder with a grey wheel and a wire brush. I use it frequently to grind lawn mower blades, clean up the bur on a sawed off bolt, and to clean off the rust on miscellaneous things. A grinder is not just about turning tools. On my turning tool grinder I have 80 and 180 grit CBN wheels. I bought the utility grinder off of Craig's list.
 
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