Author Topic: CBN Grinding Speed on A2  (Read 1305 times)

Offline NeophyteGrant

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CBN Grinding Speed on A2
« on: July 19, 2018, 09:22:41 pm »
I'm looking to sharpen A2 and PM-V11 irons and chisels, primarily bevel resetting. I've found the SG stone a bit too slow in this department, and was investigating alternatives, including CBN wheels (given that the diamond wheels are not out yet)

How fast will a low-grit CBN cut compared to a SG? I'm between this and switching to a low speed grinder with a CBN for A2 bevel resetting so my time at the wheel isn't too long. What do you guys think? The general opinion might be to just go with the low-speed, but I'm fairly invested in the Tormek, like using it, and have an irrational fear (more or less) on drawing out temper.

Thanks in advance!

Offline NeophyteGrant

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Re: CBN Grinding Speed on A2
« Reply #1 on: July 19, 2018, 10:08:03 pm »
Ken S: I'd also be interested in how you attached those Norton 3x wheels with the 12mm arbor. :)

Offline Ken S

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Re: CBN Grinding Speed on A2
« Reply #2 on: July 20, 2018, 04:31:57 pm »
Welcome to the forum, Grant.

Let me state up front that I have no experience with A2. I have nothing against A2; Family and volunteer responsibilities have severely limited my shop time.Also, my 1909 vintage bench planes predate A2, as do most of my chisels. I do try to keep current, however, that is head knowledge, not hand experience.

Out of curiosity, why are you rebeveling? I once rebeveled an old 01 high carbon steel chisel from 25° to 30º to see if the edge held up any better. That chisel usually drew the worse jobs. The higher bevel angle seemed to help. After regrinding half the bevel, it occurred to me that just grinding a small secondary bevel would probably achieve the same objective.

The Norton 3X wheels will remove a lot of metal quickly on a Tormek for very little money. I use them wet, retaining all of the cool, dust and spark free environment of the Tormek. The first one I tried was the six inch diameter 46 grit wheel from my dry grinder. It made quick work of a machine screw. The plastic reducing bushings went down to half inch, still too loose for the 12mm Tormek shaft. I used a piece of a business card as a shim. It worked well enough.

I ordered an eight inch 3X wheel. Norton refused to sell me a plastic half inch bushing for an eight inch wheel. I don't blame Norton. They probably thought I intended to remove the guards from a six inch grinder(with a half inch shaft). I could have just pirated the smallest bushing from my six inch wheel and shimmed it.

I used a piece of 5/8” OD (Outside Diameter) plastic water pipe. The Inside Diameter was 7/16”, too tight for the Tormek shaft. A 31/64” drill bit in my drill press was still just a very little bit tight. I did not have a 12mm bit. (I should have just bought a 12mm bit.) I just reamed out the 31/64” bit a little. It is not elegant, however, it works.

While doing this, make a couple spare pieces for the very losable spacer which keeps the shaft in place when the grinding wheel is removed.

I used both 46 and 80 grit 3X wheels. I found the 46 grit cut about 20% faster. The wheels cost around fifty dollars US each. Either one will do; no need for both. For fifty bucks, that's a lot of firepower for a Tormek!

They require some spacer washers to fill the shaft length. 12x38mm fender washers from the hardware store work fine. I think mine were stainless, although regular steel will work.

I dressed the wheels with an inexpensive diamond T dresser. Rick found that the Tormek TT-50 also works. (actually works better).

The 3X wheels are eight inch diameter. They work very well with the T4 and as well as any wheel worn down to that size with the T8.

CBN and diamond wheels are a more expensive choice. For essentially one time or occasional use, my choice would be the 3X. For more frequent use, especially with the T8, my first choice would be diamond, although I have also had good success with CBN. I prefer to work wet, although heat is not as much of a problem with either diamond or CBN. Not all CBN wheels can be used wet. The steel D-Way wheels which I use work wet or dry, wet requiring an anti corrosion addative.  The two diamond wheels Tormek sells for the T2 also work very well on the T4, but only dry.

My standard cutting test is to put a metal lathe tool bit in the SE76 jig set for a thirty degree bevel and grind for five minutes. The amount of grinding quickly tells the story. The large grit 3X wheels are the champs. CBN and diamond wheels also do well. The SG wheel does surprisingly well. I have not had any luck with the SB; the jury is still out for me with it.

The different wheels all start out cutting well. Where the 3X, CBN and diamont shine is that they continue cutting well throughout the test.

My question for you is how much do you value your time? Time how long it takes to rebevel one tool with the stone kept frequently regraded coarse. Multiply that time by the number of tools you have to rebevel. Is that amount of time worth spending $50 US for a 3X wheel? Is it worth spending more, up to $300 for a diamond or CBN wheel? Or, would you  rather spend that money on some good wood or a specialty plane?

Reshaping is generally a one time chore. Regular resharpening is much quicker.

Your time; your decision.

Keep us posted.

Ken

Offline NeophyteGrant

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Re: CBN Grinding Speed on A2
« Reply #3 on: July 23, 2018, 04:03:45 am »
Ken:

I can't thank you enough for expounding on your experience/testing in this area to such length. This was extremely informative.

I'm not entirely sure of my workflow/need at this point since I'm relatively new to the hobby. I've had to grind back some back bevels (they are supposed to be easier, no frills to produce a keen edge with out polishing the back much but it seem to dub the edge). I also anticipate that I'll need to occasionally to grind back to the primary bevel if my secondary bevel gets too large from repeated sharpenings. In that sense it really isn't reshaping and I wouldn't see too much grinding because it's just a hobby. I think my needs are probably low comparatively. That's why I opted for a Tormek, because although it's a trade-off in speed to a bench grinder, I felt it wasn't too much of a time sink, and I gained peace of mind with dust and blade heat (though with the cbn on low speed grinders temper is even less of a concern apparently).

My game now is to see if I can speed up the time on a Tormek and find a middle ground in terms of speed. Even if I don't do this again for a while, I know I'll loathe it taking too long when the time comes. It seems to take me half and hr or so of on and off grinding when I tested to regrind to my primary bevel angle--and in this case I had jointed the edge pretty far back to remove a back bevel and there was an out of square edges that were leftover from my first attempt to grind with worksharp as a solution (I really have tried to avoid bench grinding due to fear of heat), which I did not like.

I'm ok with 6 or 7 minutes per for something like that. It sounds like a 3x might get me there. I like the tormek experience and I'm not doing this very often, like you said--which would seem to suggest tormek--so I'm hoping the conclusion isn't just to go to cbn on a low speed bench grinder and return the tormek (save money vs the tormek sticker price, and heating, the main reason I was interested in the home doesn't seem to be an issue with cbn on a low speed grinder with cbn wheel)

I actually sort of rashly ordered a cbn wheel for the tormek before you responded (I can be impatient) but it sounds like I might keep the reducing bushing for the 1" arbor to 12 mm and instead return the cbn and just get a Norton 3x to use wet and see how fast that goes...if it's still too slow then I need to think, like you said, about how little I'll do it in the long run and whether my OCD and impatience is too insistent and I hypervalue time whether I should just get a bench grinder with cbn wheel for heat and save 400 or so over the tormek. My thought is the 3x wheel, like you said, is probably fast enough for the times I'd need to grind.


Offline Ken S

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Re: CBN Grinding Speed on A2
« Reply #4 on: July 23, 2018, 01:20:20 pm »
Grant,

Please tell us more about the CBN wheel you ordered. With a one inch bore and a reducing bushing, is it a D-Way steel wheel? What grit is it? I am leaning toward recommending that since you have already ordered the CBN wheel that you keep it and use it.

I purchased three CBN wheels when I tested them for the forum. (I have a 180 grit for the T4; and 80 and 180 grit wheels for the T8. All of my wheels happen to be steel D-Way wheels, which is not meant to imply anything negative about any other brands.) Like the 3X wheels, they cut very well. Unlike the 3X wheels, they are "plug and play" with the Tormek. They mount without requiring any plastic pipe modifications and they never need to be trued. You pay more for this convenience, however, in your case, I think you would be happier with CBN. You only need one CBN wheel.

I originally purchased my T7 to sharpen chisels. Chisels are still my favorite tools to sharpen. Once you have your bevels where you want them, resharpening them with the SG is a pleasant and not lengthy procedure. You will also find other uses for the fast cutting CBN wheel. You don't often need that much firepower, however, it is nice to have in reserve.

I think you have an opportunity to increase your satisfaction from both woodworking and sharpening. I suggest you focus on just one chisel. Stay focused on it and stay with it until you have mastered sharpening it. Watch the three online videos that Jeff Farris did. They are solid. Also, I suggest you read the Tips and Techniques first topic in the Tormek General part of the forum. (Just the first post will give you a good start.)

It should not take half an hour to sharpen a chisel. This kind of drudgery is unnecessary and will soon sour you on the Tormek. With some analysis and work on your technique, you will soon be making your chisels very sharp much more efficiently. Be patient; your time will be well spent.

Ken

Offline NeophyteGrant

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Re: CBN Grinding Speed on A2
« Reply #5 on: July 23, 2018, 09:52:35 pm »
Ken:

Thanks again for your perspective. It is a 180 grit D-Way wheel--correct. I wanted to go with the 80, but it was out of stock. That might be no matter as the 180 is plenty enough and the finer scratch pattern might make it quicker. Had a positive experience ordering. I also liked that it is advertised as being amenable to water-use (with a rush inhibitive)--after-market modifications to things haven't been to kind to me when I try my own hand at it.

It arrived today, so I'll try it out tonight and see how it goes! I will also study up more on sharpening techniques using the Tormek, as well.

Offline Ken S

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Re: CBN Grinding Speed on A2
« Reply #6 on: July 24, 2018, 02:46:43 am »
Grant,

You have the same wheel that I do. Of the two grits, I think the 180 is the more useful. It has plenty of grinding power and leaves a slightly smoother finish. All CBN and diamond wheels initially run more coarse for the first few tools. You can use this to your advantage. Use the supercharged break in period for your nastiest chisel. The wheel will soon stabilize. I use Honerite Gold as the anti rust additive. I suspect the new Tormek Anti Corrosion Compound will work fine, too.

If you don't have any Honerite Gold and are impatient, be sure to dry the wheel and bushing quickly and give them a good spray with WD-40. (WD stands fir water displacing.) Be sure to spray the bores and the balancing holes. A Scotch Brite pad will quickly remove any minor surface rust, no big deal.

I like Dave Schweitzer. He was very helpful during my tests.

Keep us posted.

Ken

Offline NeophyteGrant

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Re: CBN Grinding Speed on A2
« Reply #7 on: July 25, 2018, 07:10:39 am »
Hi All:

So I received the wheel last night. I had a bear of a time--thanks to my ineptitude--in mounting it. In what should have been a straight forward procedure, but I failed to read the instructions thoroughly (the instructions for the D-Way wheel contain the standard boxed, bold 'read first entreaty but I ignored it and just glanced at the diagram, figuring that's all I needed) and tried to force the bushing onto the arbor. Now, I was gentle and took the bushing off the wheel so it was just the  weight of the bushing on the arbor while  I eased it on--mindfulbor--and used several lubricants, but the correct method, as you guys probably guessed, is to sand either the bushing or the arbor to adjust the fit. I managed to get the bushing stuck using hand pressure and had to leverage it off, carefully, with a pipe wrench.

I then panicked and set up a dial indicator to see if I damaged the arbor but both horizontal and vertical axes showed no run-out, arbor alone, arbor with SG being the same (there was .002 movement on the vertical axis but I attributed this to the SG being out of true.) So, I lucked out. But another reminder about the virtue of reading thoroughly. Expediency can come back to bite you. Don't rush.

After sanding the inside of the bushing with 150 grit, slowly, checking for fit so as not to create any biases or wobble, I got a good friction fit and mounted the wheel. Dial indicator seems to indicate it runs true. Used a square and it looked flat, no unintended radius.

I filled the trough and ran it with water and ground a rabbet block plane and it was quick. This is the break in period but my first impression is the speed will suffice. This will need more testing but it is significantly faster. What I liked just as much, though was that it required less pressure for the same speed of cut--this makes life just that more pleasurable. Trumping even that though--it won't wear. There didn't seem to be any residue from the A2, being as it's not quite the HSS CBN seems marketed for (Dave attested to be A2 being ok on CBN--this seems to be the case).

Wear is a major pro in my case. I've become attuned to how quickly med/high alloys wear out the SG, and this has been corroborated by Tormek support. This is probably also due to my inexperience and the extra time I end up putting on it to square a blade I might have favored on one edge and skewed unintentionally--things like that. But with CBN not wearing I don't have to worry about checking and whether the SG being out of true is compounding my own user problems.

I'll reserve judgment as I continue to put it through paces and practice on my tecnique too, but I do like the CBN wheel initially.

I get some honerite gold tomorrow (doing the math, I'm wondering how far each bottle will go...) But drying down the wheel methodically and applying wd-40 (I put some VCI paper, resting on top of it to be particularly pampering) worked flawlessly--not a fleck of rust today when I went back in. My shop is moderately insulated but most of the natural humidity gets in (I'm in Chicago, so it's not awful--but it's also not Arizona)

I'm interested to try the honerite, because that will make it more practical. All, in all, even with the slower than dry speeds--though quicker than factory setup--and the significantly added cost, this looks like it might work. It's fast enough it seems, provided you don't have too many tools (volume), frequency, or major reshaping. And like tormek generally, it's just more pleasant to do wet. And easier I hear.

It's $1000 for a Tormek w/CBN vs $300 for a slow speed rikon with cbn, but the upsides might be worth it...


I guess time will tell!

G

Offline Ken S

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Re: CBN Grinding Speed on A2
« Reply #8 on: July 25, 2018, 02:13:19 pm »
Grant,

I had most of a long reply written before I finally honed in on the real issue. I think you are struggling with a problem which hindered my sharpening going back to my oilstone days. I had too many chisels and planes. I had fallen victim to the marketing propaganda of buying things in sets. I had a complete set of Stanley 40 chisels; a complete set of Marples Blue Chips; a set of mortising chisels; a number of Buck patternmaker chisels; and was starting to build a complete set of Lie-Nielsen A2 chisels. While I enjoyed collecting them, I realized that I was just making more sharpening for myself.

The problem is not the Tormek; it is too many tools, all of which seem to need rebevelling immediatly. The solution is to only sharpen what you need immediatly. You can go far with just a sharp 1/2”, 3/4”, 1/4”, and a wide chisel. Keep these razor sharp, and you will go far. If you run into a situation where you feel more comfortable with another size, sharpen that one.

Take your time with your first chisels. Use a small square and check often. Make course corrections when you first notice being out of square. Devote your full concentration to one chisel. Keep others off your bench and out of your mind. Start with the half or three quarter size. Narrow chisels are more difficult to sharpen.

I still don't understand why you feel the need to change the bevel angle. You may have a good reason. If you do not, you are wasting a lot of time and steel.

Chisels and plane blades normally take a couple minutes to resharpen. A2 may take a little longer, however, anything over five or ten minutes would indicate a technique problem. If you true your stone very lightly, you will have it cutting optimally.

Be patient and persistent. Once you get beyond your initial difficulties, you will have many years of enjoyably sharp tools.

Keep posting.

Ken