Overview But Long CBN Subjective Review!
Below is a long write-up explanation, observation, and brief first time use of New CBN wheels for sharpening. (I posted this originally on a woodworking forum that I frequent.)
CBN grinders; Are They Making Tormek Obsolete?
That might seem like a bold statement, but my 20 minutes of use of the CBN wheels accomplished more than a couple of hours did on my Grizzly "Tormek" knock-off. I do know that the Tormek has MUCH better wheel than the Grizzly, but the problem with both is the speed - SLOW. If one is not used to the finer and superior sharpening of slow wet grinders, you don't know what you are missing. ON the Other Hand, if you can't imagine such a fine and superior sharpening being done fast, then at least open your mind to the possibility, and just possibly be surprised.
Explanation for those not familiar with good grinding systems:
Most bench grinders come in either of two speeds 1500 RPM (or 2000) or 3500 rpm, - or in some cases dual speed, or adjustable speed between those figures. The problem with 3500 rpm is that the speed causes turning tools and hardened hand chisels to heat up and unless very experienced and knowledgeable, will damage the ability to stay hard and keep an edge. ( just keeping the explanation simple.)
The way around the overheating has been to change the type of stone AND slow down the speed. Helps considerably. Still 1500/2000 can damage chisels from the heat without care. In fact many professional turners who use bench grinders use the 1500 RPM bench grinders because its slow speed keeps heat down.
(NOTE: I often use the word "SHAPE" in one context and SHARPEN in another. These are different terms. Most turners understand this, but for the un-initiated they are different. Shaping means to get it to the shape needed for turning as not all tools come ready to use, and some come with the need for the user to get it to shape. SHARPENING is after getting it to shape.)
ENTER: SLOW Grinders and water cooled grinding wheels.
Tormek has been the Cadillac of wood turner grinders (not comparing it a Rolls Royce). It is very slow (110 RPM?) and water cooled. Lots of accessories have developed over the last 20 -25 years and before. Tormeks will shape and then put a great edge on without heating and destroying the temper of the tool.
The one drawback that no one (until recently) complained about because there were no great alternatives: It was slow. OK, it IS slow. But most Tormek users were taught the idea that slow and precise were better. It was and is! All basic thought (except with belt grinders) was that SLOWER is better. Once the tool(s) are sharp, it only takes a few minutes to bring it back to shape/sharpness from then on. And it has a wide wheel which helps with wide chisels. Most turners, chisel sharpeners and knife sharpeners accept the time needed to sharpen. Even bringing to shape or re-shaping a turning chisel takes time - 10, 15, 30 minutes, and an hour sometimes. Again, with nothing better in its price range, then the Tormek wins for what it does. QUALITY GRIND!
The main alternative to TORMEK (and the Tormek look-a-likes - Grizzly and Jet) were Aluminum Oxide stone wheels on Bench Grinders. Tormeks usually required $500 - $700 initial investments though, and sometimes more for the Tormek specific accessories. Two speed Bench Grinder with Aluminum Oxide wheels could be had in the $200 range, give or take a sale, plus $50 - 150 for accessories. Bench Grinders with Aluminum Oxide did well for most people, but it needed some experience in keeping the tools cool. One thing I have learned is that HSS Steel might get hot, and to a certain temp that is OK, but Don't Quench hot HSS in cold water - so I have been told, as it will cause the HSS edges to fracture.
THEN CBN Grinder wheels.
CBN has been around for 50 years or so, but only in the last 5 to 6 years has it begun to creep into the turners workshops. If you read turners reviews from 5 or 6 years ago, you will see some differences from today's reviews and recommendations. On two reviews and recommendations 5 & 6 years ago, it was recommended to use CBNs at 1500 RPM. Old wise turners evidently held on to the slower speed as a necessity. However recommendation from manufacturers - they don't back away from recommending 3500/3600 RPM on 8 inch wheels.
I can't give a complete review, but my assessment is with about 20 minutes use. But that 20 minutes was revealing. I received two 8 inch wheels, a 180 and a 600 grit on Monday. I haven''t had time since then to fully check them out as I work with numerous churches in our area in consulting and coordinating summer (and other) events, and this first week of June is the busiest of all weeks. I returned home Monday at about 4:00 PM had 1 hour and 15 minutes before having to leave to go to a church crawfish boil. I was NOT going to miss that.
I had read about one guy who had not taken the wheel off of his Tormek in about 15 years. It took him saturating the stone and shaft with penetrating oil overnight for him to remove it. That was an important point. I took the nut off of one grinder wheel on my VS 8" Delta grinder, and the outside washer did not want to come off. Tapped with a hammer on a screwdriver. Twisted, pulled, turned, it took about 20 minutes to get that wheel off. Then to the other side. Same thing, same amount of time. Cleaned the shafts off and added a CBN wheel. Didn't seat well. Took it off and added a washer to the inside. On the outside of the wheel, I added the optional (Ordered with the wheels) dual washers that help in seating it correctly. Did the other side. Put the Delta tool rest back on and gave it a try.
WOW, JUST WOW! SMOOTH! No VIBRATION. Wheels don't wobble at all.
The Delta tool rest is not good at all, but all of my grinding jigs were purchased for the Grizzly, so they would not fit on the Delta. I had to use the flimsy Delta tool rest. I picked up a 1 1/2 inch wide chisel that had been used to scrape glue, was dull and had a couple of nicks from hitting small nail heads. Using the CBN wheels at 3500 RPM, there was a minuscule amount of very small sparks. Not totally spark free as I was kinda expecting, but nothing anywhere near a normal grinding wheel at creating sparks. Second thing I noticed within about 30 seconds - WEAR A MASK. Normally I do, but I needed to get a test done and then go get some crawfish. The CBN wheels do produce VERY FINE dust and it flies/floats around.
Using the third rate Delta tool rest, I held the chisel firm and moved it back and forth across the wheel 4 times. It shaped and cut those nail notches out within 1 minute. That would probably have taken about 20 to 30 minutes on the Tormek. One other misconception: It does get hot when you are not expecting it, but not too hot to hold or put your thumb just below the blade to hold firm. I purposely put the chisel back on and held it for about a minute; the very very top edge did change to a light brown, so I know that it can get hot. The rest of the tool was not that hot. Then I looked at the grind, and it it looked SUPER. I am one that will always hone my chisels, hand chisels, knives and turning chisels and the 180 does leave it very sharp but honing will make it better. Next, I took a 1 inch chisel that had a flat grind on it and put a hollow (concave) grind to it. That took about 1 minute. I tried it on the 600, and the 600 did make it smoother. I am going to like that and use the 600 for touch ups and it will make honing come faster and easier than the Grizzly grind.
The CBN wheels do not change in size with age; they do not need to be dressed to re-flatten and they do not wear like aluminum oxide or other stone wheels. They do not need and it is recommended NOT to use water with them other than a spritz on occasion to keep the dust down if you want that. They run Truer from the get go. I got mine from WoodTurnerswonders.com, and while not included, they offer a set of washers that work together to allow for alignment/runout problems. I got two sets. They should be included but even then they were less than $5.00 each set.
The end result is that one can shape tools in minutes on the CBN Wheels - that would take at nearly an hour or more on a Tormek or Grizzly slow wet grinder - without damaging the HSS/hardened steel from heat. The CBN will make the Tormek/Grizzly obsolete unless Tormek adapts. The only solution (that I see) that will save the slow wet grinders is to find a way to speed up the grinder to 1000 RPM for use with a CBN wheel, otherwise they will be like Schwinn in the late 70s early 80s who thought that mountain bikes were only a fad; Schwinn almost went broke and out of business holding on to the old ways attitude.
OPTIONS NEEDED (for me):
I really need a Wolverine like system for sharpening on the Delta grinder. I have several Tormek accessories for the Grizzly that I could use if I add the Tormek like bar to the Delta. I have thought about it, but one bar for each side plus mounting hardware would run close to that of the base cost of a Wolverine system. I also have looked at making my jigs. I looked at McMaster Car for rods to make my own Tormek Rod mounting system. It would take 1500mm long 12mm diameters rod to make two for the Delta, (one for each side) and those linear 12mm rods cost $50 - $60 plus shipping. (1/2 inch won't work.) I decided to leave my Tormek Grizzly accessories to the Grizzly. Still deciding whether to order the Wolverine system. $133 at Amazon for the full needs.
END THOUGHTS:
The CBN wheels accomplish in seconds what would take 10 minutes or so on a Tormek. It accomplishes in minutes what would take an hour on a Tormek and do it EVERY TIME as fine as the Tormek. Even with a CBN wheel on the Tormek, it still runs at 110?RPM. What does speed play in grinding, if temps can be held down to undamaging temps? . . .
I tried grinding the 1 inch hand chisel with the 180 grit at 2000 RPM. It did great; then I turned the speed up to 3500 and it was VERY noticeable that the grinding rate on the tool increased what seemed to me to be two fold. 1. FASTER SPEED makes a big difference in grinding with the CBN; The faster the better - up to a point of about 3500rpm; 2. CBNs are equal to slow wet grinder's in precision, smoothness and quality of grind; 3. CBNs do keep the heat down considerably compared to Aluminum Oxide wheels;
Thus high speeds, quicker work, quality grind and undamaged tools from heat. Tormek, you have lots of followers, but I have already seen posts that the CBN on the Tormek is still painfully SLOW in shaping and sharpening dull blades. There is a crack in the following, and I imagine that new folks will go towards CBN wheels in the very near future for sharpening needs.
CBN works best at speed, works cool enough at speed and gives quality grinds too! Mildly expensive , (More than a Grizzly,) but less than a Tormek or Jet.
