This is NOT a new sharpening thread...but...

[Lasse Hilbrandt]

I was dressing up some old chisels on my Norton stones yesterday. They needet a bit of work, so now my 220 grit stone is almost toast. It wears soo fast. Currently Im happy with my 1000, 4000 and 8000 Norton stones, but I need another stone for rough work that dont wear so fast.

What would you recommend ?

[Robert Engel]

Diamond coarse or xtra coarse (320). Great for flattening too.

[Robert Hazelwood]

I have the same Norton 220 waterstone and it really does wear quickly, yet doesn't seem to cut exceptionally fast. Not ideal for a blade back since the stone will constantly be going out of flat.

So far I haven't found anything better for heavy blade prep work than 60 or 80 grit sandpaper stuck on a granite surface plate. I do have diamond stones, DMT x-tra coarse (220) and coarse (320), but they are slow on a broad surface like a blade back. They are good at cleaning up after the coarse sandpaper, though.

I would like to get a lapping plate, or some glass with plastic laminate, and experiment with loose grit to see if that is less of a hassle than sandpaper.

[Prashun Patel]

I'm partial to Worksharp with 'diamond lapidary plates' you can buy cheap on 'bay.

They are very quick for bevel setting and back flattening. You can get the lap plates in 80, 150, 220, 500.

[Patrick Chase]

I was dressing up some old chisels on my Norton stones yesterday. They needet a bit of work, so now my 220 grit stone is almost toast. It wears soo fast. Currently Im happy with my 1000, 4000 and 8000 Norton stones, but I need another stone for rough work that dont wear so fast.

What would you recommend ?

The obvious answers here is a bench grinder :-).

If it must be a stone, then I like the Suehiro Cerax 325 in that range. It's $50 or so for a double (50 mm) thickness stone from CNTG. Stu has a 25 mm version for a bit less than half that.

One word of warning: All coarse stones are and must be fast-dishing/wearing than fine ones. I say "must be" because coarse abrasive particles dull and need to be released just as fast as fine ones, but each layer of coarse abrasive is much thicker. It therefore isn't realistic to expect that a 220 would wear like, say, a 1000 while effectively working the same steels. Fortunately coarse stones are also a lot cheaper.

Sandpaper on granite/glass works for infrequent grinding, but gets expensive in a hurry. The abrasives in sandpapers are no different/better than those in stones but they cost a lot more to replace when they dull (put another way, it's much cheaper to replace a given volume of Al-Oxide or Si-Carbide particlesby wearing them off of a stone than by replacing a sheet of sandpaper). Of course the same argument also applies to belts on a belt sander, with the main difference there being that you can tolerate somewhat duller particles

[Lasse Hilbrandt]

What kind of sandpaper do you use?

[Mike Brady]

Yes, it is another sharpening thread... Lots of ways to throw money at your task here. Those work, but coarse sandpaper on something flat gets it done, cheap. I would only caution against the diamond stones. There are tons of references right here in this forum about diamond plates disappointing their purchasers. That hasn't changed since last week.

[Jim Koepke]

My vote goes with the sandpaper on granite.

Since flattening the back of a blade is usually only done when a blade needs rehab it doesn't pay to keep buying stones for the coarse work.

For quite a while my chisels were coming from eBay, yard sales, estate sales and wherever else they could be found. Most of them needed lots of work to get them in shape. A disk sanding system works, but can eat the abrasive fairly fast.

Currently my granite has 360 grit paper attached. I haven't been having a steady influx of beater chisels like in the past.

jtk

[Patrick Chase]

I was dressing up some old chisels on my Norton stones yesterday. They needet a bit of work, so now my 220 grit stone is almost toast. It wears soo fast. Currently Im happy with my 1000, 4000 and 8000 Norton stones, but I need another stone for rough work that dont wear so fast.

What would you recommend ?

The obvious answer here is a bench grinder :-).

If it must be a stone, then I like the Suehiro Cerax 325 in that range. It's $50 or so for a double (50 mm) thickness stone from CNTG. Stu has a 25 mm version for a bit less than half that.

One word of warning: All coarse stones are and must be faster-dishing/wearing than fine ones. I say "must be" because coarse abrasive particles dull and need to be released just as fast as fine ones, but each layer of coarse abrasive is much thicker. It therefore isn't realistic to expect that a 220 would wear like, say, a 1000 while effectively working the same steels. Fortunately coarse stones are also a lot cheaper.

Sandpaper on granite/glass works for infrequent grinding, but gets expensive in a hurry. The abrasives in sandpapers are no different/better than those in stones (unless you get into exotic SG/ceramic papers) but they cost a lot more to replace when they dull. Put another way, it's much cheaper to replace a given volume of Al-Oxide or Si-Carbide particles by wearing them off of a stone than by replacing a sheet of sandpaper. If you managed to wear out a Norton 220 then I strongly suspect that sandpaper wouldn't be economical for you.

[paul cottingham]

I flatten with a diamond stone. Works great. I grind with a Viel belt grinder in various grits. Worth a try.

[lowell holmes]

My vote goes with the sandpaper on granite.


jtk

If you have the Deulan jig, you can sharpen jointer knives on granite and sandpaper. The cost of a half size granite plate is about the same cost as new knives.
Even sharpening services are going to cost $25-$30. I bought a granite plate and use 320 wet or dry sandpaper. That setup with a LV honing guide makes short work of old beater chisels.

[Patrick Chase]

If you have the Deulan jig, you can sharpen jointer knives on granite and sandpaper. The cost of a half size granite plate is about the same cost as new knives.
Even sharpening services are going to cost $25-$30. I bought a granite plate and use 320 wet or dry sandpaper. That setup with a LV honing guide makes short work of old beater chisels.

Out of curiosity how many chisels do you think you can work on a sheet of SiC (a.k.a. wet-or-dry) paper before it starts to break down and polish?

3M #320 Wetordry is about $1 per 9x11 sheet in bulk, which means it costs about the same as 1 mm of a coarse waterstone. I estimate that I can grind at least 10 seriously dinged tools per mm with a stone like the Cerax 325. From my own experience I can't get anything like that sort of yield with Wetordry, but maybe I just grind on it too hard or something.

[lowell holmes]

I never have considered the cost. :)

[Warren Mickley]

I have the Norton 220 water stone. It is a very poor stone. I cannot imagine anyone with experience recommending it; the company and the vendors should be ashamed. For rough work, both the coarse Carborundum and the coarse India are a much better choice. They probably have 20 or 50 times the life. I have sharpened about 11 tools for every penny spent on stones.

[Jim Koepke]

I am happy with the abrasive papers Supergrit.com carries. The price is reasonable and like others, I have better luck with a coarse sheet than a coarse stone.

jtk

[Patrick Chase]

I have the Norton 220 water stone. It is a very poor stone. I cannot imagine anyone with experience recommending it; the company and the vendors should be ashamed. For rough work, both the coarse Carborundum and the coarse India are a much better choice. They probably have 20 or 50 times the life. I have sharpened about 11 tools for every penny spent on stones.

I agree w.r.t. the Norton 220. I gave one as a gift to a friend once, and learned much later that it had not been a success.

FWIW my preferred coarse stones are a Norton Carborundum stone (for easier steels), a Sigma S-II 240 (for difficult steels), a Suehiro Cerax 320 (general grinding), and a Sigma Power 400 (specifically for face-lapping). If I had to pick one it would be the Suehiro. I was being *very* conservative with the yield estimate I gave above BTW.

[Lenore Epstein]

Out of curiosity how many chisels do you think you can work on a sheet of SiC (a.k.a. wet-or-dry) paper before it starts to break down and polish?

3M #320 Wetordry is about $1 per 9x11 sheet in bulk, which means it costs about the same as 1 mm of a coarse waterstone. I estimate that I can grind at least 10 seriously dinged tools per mm with a stone like the Cerax 325. From my own experience I can't get anything like that sort of yield with Wetordry, but maybe I just grind on it too hard or something.
IME, SiC wet/dry paper--whether PSA or used with spray adhesive--has broken down very quickly when flattening, changing bevels, etc. Maybe I did it wrong, but I moved away from sandpaper sharpening quickly because I went through so much paper.

I bought a big fat King Deluxe 300 stone on Amazon for under $40 that does an excellent job and dishes about as fast as my Shapton Pro 1000--which isn't fast at all. Only caveat is that it needs frequent conditioning with a diamond stone (maybe a Nagura would work) in order to remove glazing, but it fixes up machine marks and does small bevel changes pretty quickly while leaving a nice even scratch pattern that's easy to remove with the Shapton 1000. I haven't used other King stones, but I agree with Stu at Tools from Japan that it's a completely different animal than their more typical soft stones.

For really fast material removal I use the blue 80 and 120 Norton ceramic/alumina sanding belts (a la The Schwarz) glued to a stone (a dead flat piece of piece of limestone bought at the Habitat for Humanity store for $1). They quickly flattens, grinds out larger chips, and/or changes bevels on mangled plane blades and chisels, and so far the belts show zero wear.

Of course, a grinder would make life even easier, but that would be way too much mess with my "shop" located in my living room, and the sanding belts probably work just as fast.

There are a lot of options to choose from, but this was the cheapest and easiest option I could find and fits my situation perfectly!

ETA: Because the King is so coarse I bought an iWood 140 from Tools from Japan, rather than wearing out the very pricey Atoma 400 I use on the Shaptons. I'm very happy with both of them.

[Patrick Chase]

IME, SiC wet/dry paper--whether PSA or used with spray adhesive--has broken down very quickly when flattening, changing bevels, etc. Maybe I did it wrong, but I moved away from sandpaper sharpening quickly because I went through so much paper.

Trying to put some numbers behind the question of stone vs sandpaper life. Let's use #320 as a reference point, which corresponds to 40-micron particle size. A #320 stone would have about 30 layers of particles per mm of thickness making reasonable assumptions about particle shape/packing and amount of binder. Sandpaper has a single layer of particles (or less if it's open-coat, but let's assume closed-coat to be generous to the "scary" people in our midst), so 1 mm of a 3x8 stone contains abrasive equivalent to 3x8x30 = 720 square inches of sandpaper. Coarse stones go for about $1/mm, so sandpaper would need to be about $0.15/sheet to be cost-effective.

This assumes that the stone is properly matched to the steel and specifically that it isn't too soft such that it sheds abrasive particles before they break down - this is the Norton 220's big failing IMO. They may have designed it with HSS in mind (the Sigma S-II #240 also breaks down fast, but it's advertised specifically for difficult steels so in that case it's working as intended), or they may have just screwed up.

One interesting thing to note: Stones do relatively better at higher grits (more layers of abrasive per mm), and worse at lower grits (less layers). When you get down to #120 or below sandpaper starts to look more attractive, though such stones are also cheaper per mm thickness so the cost per unit sharpening never actually crosses over in favor of sandpaper.

EDIT: There is one huge point in favor of sandpaper that I neglected: Convenience. There's something to be said for being able to slap down a sheet of sandpaper with a little Super-77, have it be dead-flat throughput the process, and then being able to pitch it and wipe the granite/glass with some acetone when done. Low-tack PSA papers like the 3M Stikit line are even more convenient, but cost-effectiveness becomes a lost cause once you start messing around with those.

[Trevor Goodwin]

For flattening new chisels that don't need much work, I've gotten away with my Naniwa 220 grit. The severity and effect of the dishing everyone seems to worry about it is largely dependent on how the stone is used. I don't use a side-to-side motion and I don't just concern myself with the last 1/2" of the chisel, rather I use a "edge-to-handle" motion concentrating most of the pressure on the edge, this leave a uniform finish and doesn't dub the sides of the chisel. I do this on the long edges and the short edges of the stone to distribute the wear, and I figure because I'm not using a repetitive back-and-forth motion across the length of the stone, any contours in the stone have less effect on the final flatness of the chisel back.

For chisels that need a lot of work, I've had good results using an extra coarse DMT plate (until it lost its bite) and Norton SiC stones: http://www.sharpeningsupplies.com/Norton-Crystolon-Bench-Stone-8-x-3-P24.aspx
At $19 a stone it's hard to beat those stones. They wear a lot slower than Japanese water stones but can lose their bite just like diamond stones. I've had success refreshing them with a Norton flattening stone, but at that price you could buy two of the same stone and rub them together.

[Lenore Epstein]

Low-tack PSA papers the the 3M Stikit line are even more convenient, but cost-effectiveness becomes a lost cause once you start messing around with those.
As a complete aside, I quickly discovered that soaking the paper with simple rubbing alcohol for five minutes or so softens Super 77 enough to be easily scraped off with a razor blade with any residue wiped off with an alcohol-soaked paper towel. How, you ask? Because the spray bottle of 50/50 alcohol/water I use when tuning skis was sitting on the shelf next to my stack of sandpaper...and before I knew it my wet/dry paper was curling up off of the glass. Doh!

I'm glad to trust your calculations, but another good thing about sheet abrasives is that they're handy when doing things like flattening planes, which is what pushed me toward the sanding belts, which are much tougher than wet/dry paper--maybe because of the cloth backing, maybe the abrasive. Who knows?

[Patrick Chase]

As a complete aside, I quickly discovered that soaking the paper with simple rubbing alcohol for five minutes or so softens Super 77 enough to be easily scraped off with a razor blade with any residue wiped off with an alcohol-soaked paper towel. How, you ask? Because the spray bottle of 50/50 alcohol/water I use when tuning skis was sitting on the shelf next to my stack of sandpaper...and before I knew it my wet/dry paper was curling up off of the glass. Doh!

I'm glad to trust your calculations, but another good thing about sheet abrasives is that they're handy when doing things like flattening planes, which is what pushed me toward the sanding belts, which are much tougher than wet/dry paper--maybe because of the cloth backing, maybe the abrasive. Who knows?

The abrasives in belts are the same as in stones or papers (unless you're using exotic stuff like Regalite, but then cost becomes an issue). The difference is in the substrate - cloth is a lot tougher than paper. You may be using too much pressure if you're actually detaching the grits from the paper or otherwise trashing the substrate before you wear the abrasives out, though.

I've been tuning skis for a long time (decades, versus merely years of woodworking), and use a 50/50 methanol/water mixture. I can't remember where I picked that up - it certainly wasn't from SVST/RaceWerks (they'd rather sell you "Secret Sauce" for an arm and a leg). Maybe Tognar? At least the woodworking community hasn't come up with anything quite as obscene as powdered fluoro speed overlays.

Hey wait, maybe that's a business opportunity: High fluorographite polymer plane base waxes. Maybe somebody like L-N could advertise pre-impregnated bases that should only be prepared with their exclusive wax line?



For those not in on the joke, a major ski manufacturer once partnered with the leading wax producer and made "co-branded" bases that were only supposed to be prepared with said wax producer's stuff. What made it amusing was that the specific wax they chose was a fairly mediocre paste, of the sort that serious skiers mostly use to prevent accumulation on ski topsheets. I still have a can of the stuff lying around that I use for exactly that purpose (and to make my kids' skis tolerable in spring conditions).

[Lenore Epstein]

I've been tuning skis for a long time (decades, versus merely years of woodworking), and use a 50/50 methanol/water mixture. I can't remember where I picked that up - it certainly wasn't from SVST/RaceWerks (they'd rather sell you "Secret Sauce" for an arm and a leg). Maybe Tognar? At least the woodworking community hasn't come up with anything quite as obscene as powdered fluoro speed overlays.
Got it from the tuning forum on epicski.com. Epicski's a bit more...er...aggressive that SMC, but some of that is the presence of racers, instructors, and self-described extreme practitioners of the sport. Nonetheless, the advice I got enabled me to make my skis sharp and really slick. Anyhow, someone was about to order a big bottle of somebody's "sauce" and was quickly straightened out. Kind of like the $20 bottles of camellia oil marketed on a lot of tool sites.

I'm a late bloomer, only started skiing five years ago and waxing/tuning about 3 seasons ago. Sadly, my tuning gear is packed away in the closet because I can't ski this season for health reasons. The upside is that I now have a lot of time to obsess about tools!


Hey wait, maybe that's a business opportunity: High fluorographite polymer plane base waxes. Maybe somebody like L-N could advertise pre-impregnated bases that should only be prepared with their exclusive wax line?

Ooh, and then we can have endless battles about how much wax a plane base can "absorb!"

[Patrick Chase]

Ooh, and then we can have endless battles about how much wax a plane base can "absorb!"

Depends whether it's powdered metal (a.k.a. "sintered" :)).

Ironically enough some sintered metals actually *can* be made porous and thereby contain lubricants, for example some self-lubricating bronze bushings are made that way.

EDIT: You're right about Epicski. I joined a few years back and concluded after a few days that participation was futile.

EDIT 2: Sorry to hear about your health issues. I went through a layoff like that many years ago after I blew out 3 knee ligaments in one crash (went down at speed while training DH on a pair of 220s - that's when I realized that weekend warriors have no business racing speed events). And with that I will stop straying OT.

[lowell holmes]

I must say that when I have a piece of curly maple or cherry on the bench, I don't worry about the cost of a sheet of sandpaper.:)
I just want my tools to be sharp. I've used stones, hones, sandpaper or whatever is available. That being said, I keep a fine diamond plate on the bench and I know how to sharpen free hand. I will stop what I'm doing and touch up and edge if needed.

[Jim Koepke]

I try to be economical buying PSA rolls. The current price for a 4-1/2" X 4' strip cost about $2.25. It works faster and seems to last better than any of my coarse stones. I have some mounted to a piece of corian for flattening stones. It is still doing the job after a few years. There is also some mounted to my hunk of granite that has been at least a year since being changed. It gets used for a lot of things other than blades and plane soles.

The important thing to me is it is a lot less work to change out the abrasive than it is to keep the water stones working. Maybe I have the wrong coarse water stones. I am not going to throw more money at this trying to find the right coarse water stones.

My philosophy is to stick with what is working. I do not mind trying new or different ways. Something has to prove it is better than what is already working to get me to change my ways.

Going the full scary sharp method is more expensive in the long run. For just the rough stuff, it may be a touch more costly, but it sure beats constant maintenance of a coarse stone that wears to fast for my liking.

jtk

[lowell holmes]

I've had my diamond hones for about 10 years. I suppose they are the least expensive.

However, that piece of sapele on my bench cost more. I'm not worried about the cost of sharpening when I'm working on it.

Clarke Hardwood Co had a bin of curly walnut. I think I will make a document box for a Grand Daughter away at the University out of it. I will have a lot more money in the wood than I will with sandpaper.

[Patrick Chase]

I've had my diamond hones for about 10 years. I suppose they are the least expensive.

However, that piece of sapele on my bench cost more. I'm not worried about the cost of sharpening when I'm working on it.

Clarke Hardwood Co had a bin of curly walnut. I think I will make a document box for a Grand Daughter away at the University out of it. I will have a lot more money in the wood than I will with sandpaper.

Yeah, very good point. As much as my obscene (and definitely non-economical) collection of stones is worth, the wood stack is worth more and time to actually work it is worth the most of all.

[lowell holmes]

I have my collection of stones too. I have the full set on Norton water stones.
I don't like having water nor oil around my bench, so I use diamond hones.
I do spritz them with water from a water bottle, but it is easy to contain.

[Lenore Epstein]

Ray, just for giggles, which brand of PSA paper do you use?

[Mike Holbrook]

As I have posted quite a few times before I am a grinder convert. I fought the idea for years, trying all sorts of stones, natural, ceramic, diamond....For me in the final analysis the larger jobs require many more strokes across some sort of abrasive surface. I am not so young any more and my hands are much more sensitive to all the abrasives and fine metal they make. I use an electric grinder so I can get the job done, on the PDQ, and get back to working wood.

In my opinion using grinders has more to offer than just removing metal faster. I finally experimented with the whole concept of hollow grinding and find it a much better method of sharpening for me. I don't like to have to hunt for and set a jig when I want to sharpen. Hollow ground edges are very easy to hone by hand without a jig. The edge naturally registers against the two sides of the hollow, removing most of the guess work/rocking when touching up an edge after it gets a little dull. Most of the time a few passes on medium and extra fine 2x8" Spyderco stones and I am back at work. The Spydercos are very hard which translates into not needing to flatten them. They do not require water. I love this system as it is much quicker, less messy, very easy to do by hand without any sort of jig.

For me a workable grinder set up changed the whole way I sharpen, making the whole system less complicated and easier to do, well worth any negligible cost vs stones IMHO. I like CBN wheels. I understand that many consider them needless expense. For me having an abrasive surface that will grind as fast and cool as a CBN wheel which will also probably out last me is worth the cost, saving time, effort, worry, every time I need to sharpen. In my experience a grinder solves more sharpening scenarios than any other device, more than several stones. I wish I had followed the lead of guys like David Weaver and Derek Cohen years ago.

[Patrick Chase]

As I have posted quite a few times before I am a grinder convert. I fought the idea for years, trying all sorts of stones, natural, ceramic, diamond....For me in the final analysis the larger jobs require many more strokes across some sort of abrasive surface. I am not so young any more and my hands are much more sensitive to all the abrasives and fine metal they make. I use an electric grinder so I can get the job done, on the PDQ, and get back to working wood.

In my opinion using grinders has more to offer than just removing metal faster. I finally experimented with the whole concept of hollow grinding and find it a much better method of sharpening for me. I don't like to have to hunt for and set a jig when I want to sharpen. Hollow ground edges are very easy to hone by hand without a jig. The edge naturally registers against the two sides of the hollow, removing most of the guess work/rocking when touching up an edge after it gets a little dull. Most of the time a few passes on medium and extra fine 2x8" Spyderco stones and I am back at work. The Spydercos are very hard which translates into not needing to flatten them. They do not require water. I love this system as it is much quicker, less messy, very easy to do by hand without any sort of jig.

For me a workable grinder set up changed the whole way I sharpen, making the whole system less complicated and easier to do, well worth any negligible cost vs stones IMHO. I like CBN wheels. I understand that many consider them needless expense. For me having an abrasive surface that will grind as fast and cool as a CBN wheel which will also probably out last me is worth the cost, saving time, effort, worry, every time I need to sharpen. In my experience a grinder solves more sharpening scenarios than any other device, more than several stones. I wish I had followed the lead of guys like David Weaver and Derek Cohen years ago.

Same here - that's why the first line in my first reply to the OP was "the obvious answer here is a bench grinder".

Interestingly the stone-vs-sandpaper tradeoffs carry over to power-assisted sharpening, except now they're called "grinding wheels" and "sanding belts/discs" respectively. The bottom line is about the same too: Sanding belts/discs are convenient (no dressing etc) but wheels are hard to beat for cost per sharpening.

[george wilson]

I'll say it again: If you invest in a diamond stone and a coarse and a fine Spyderco ceramic stone,you will not have to spend another dime for a very long time.

And,if you want a diamond stone for cheap as dirt,go on Ebay and find the Chinese guy who sells 6" diameter diamond impregnated lapidary disks for $9.00 each. If you can get by without the rectangular shaped diamond stone,these disks are nickel plated matrix based,and are just a good as any other diamond coated stone. They are 1/16" thick steel,and they are FLAT. I have a horizontal/vertical 200 RPM diamond grinder. I paid $250.00 for a wheel for it before I discovered the cheap Chinese discs. These cheap discs can be had anywhere from coarse to 2000 or 3000 grit(Can't recall how fine they go). A bit of alteration,and they work fine on my grinder. But YOU can use them for hand honing just as they are.

I strop on a piece of MDF with LV green buffing compound. I keep the MDF strop where it can't get grit or shop dust particles floating around and getting on it.

[Mike Holbrook]

I apparently missed the Chinese lapidary disk information when George posted it before, great to know about that alternative, will check it out. I have a couple pieces of MDF, and green compound I picked up after reading another of George's posts. I find that they work well for me too. I plan to try a little diamond paste on one of the MDF blocks to see if I like it vs green compound and an extra fine Spyderco. The MDF blocks with some sort of compound may work faster and polish better than a Spyderco extra fine stone. When I was a kid my cousin and I would grind fine sand into soft wood and use it to sharpen rough tools with, which is sort of similar in function.

[Patrick Chase]

I'll say it again: If you invest in a diamond stone and a coarse and a fine Spyderco ceramic stone,you will not have to spend another dime for a very long time.

And,if you want a diamond stone for cheap as dirt,go on Ebay and find the Chinese guy who sells 6" diameter diamond impregnated lapidary disks for $9.00 each. If you can get by without the rectangular shaped diamond stone,these disks are nickel plated matrix based,and are just a good as any other diamond coated stone. They are 1/16" thick steel,and they are FLAT. I have a horizontal/vertical 200 RPM diamond grinder. I paid $250.00 for a wheel for it before I discovered the cheap Chinese discs. These cheap discs can be had anywhere from coarse to 2000 or 3000 grit(Can't recall how fine they go). A bit of alteration,and they work fine on my grinder. But YOU can use them for hand honing just as they are.

I strop on a piece of MDF with LV green buffing compound. I keep the MDF strop where it can't get grit or shop dust particles floating around and getting on it.

Do you happen to know if those Chinese disks are mono- or polycrystalline?

I personally don't like diamond plates with nickel-bonded particles due to scratch [non]uniformity. Almost every plate I've ever used seems to have some "outlier" particles that leave deep scratches, even after break-in. From looking at SEM shots other have posted and based on my knowledge of the processes involved I suspect that this issue is more a function of the bonding process than of the abrasives themselves. A polycrystalline plate won't last as long but might be better in that regard since the "sore thumb" particles would tend to break down quickly, and at the price you cite life wouldn't be such a concern anyway.

I've had very good experiences with diamond lapping films (3M 661X/668X) and pastes. The adhesive bonding process for the films seems to achieve very good uniformity without any break-in, and the pastes are basically as good as the substrate you use them on (mild steel in my case - I take my plates to the machine shop down the road for regrinding whenever they start to go out of flat, which isn't often). I've had very good luck with some of the cheap polycrystalline diamond pastes that you can find on Amazon - you don't need the robustness of monocrystalline diamonds for that, and in that sense DMT/Norton/etc pastes are overkill.

[george wilson]

I like the bonded plates just fine,and haven't noticed any scratches from larger particles. Your mileage may vary. They ARE CHINESE,remember. I prefer to not use paste. I have several tubes,but they get wiped off the rotating plate,and I don't like turning diamonds loose around my precision machinery. Using them by hand motion only is different.

Patrick,you are lucky to be able to go to a machine shop and get small things ground. Here,they only seem interested in fat government contracts,and charge an arm and a leg for work. Fortunately,back in the early 70's I began to assemble my own machine shop.I hadn't had access to lathes and mills since the 50's. I ought to hang out a sign that says "The Poor Man's Machine Shop". It would be legal where I live. Except I know I'd only get badly rusted farm machinery parts to work on! No fun in that!!

[Ray Selinger]

What is a CBN wheel? This is a good discussion, I have quite a number of used and fleamarket chisels that need that first reshaping. I think the shaping is more correct term than sharpening.

[Patrick Chase]

What is a CBN wheel? This is a good discussion, I have quite a number of used and fleamarket chisels that need that first reshaping. I think the shaping is more correct term than sharpening.

Cubic Boron Nitride. It's crystallographically similar to diamond, but with Boron and Nitrogen atoms instead of Carbon. It's a hair softer than diamond but has much better life when grinding HSS at very high temperatures (700C and above).

Because of its suitability for bulk production grinding of HSS it's widely available in grinding wheels, and that makes it a reasonable choice for woodworkers even though diamond wheels would be slightly better for the less intensive grinding we do.

[Mike Holbrook]

Ray, Patrick answered your question quite well. I will just add that woodturners have been using CBN wheels for sharpening turning tools, often HSS or other hard steels, for a long time now. Turners dull tools fast and most report that they just can't wear CBN wheels out. Another major bonus of CBN wheels is they run much cooler than other grinding materials preventing most over heating scenarios. For "flat" woodworkers these wheels should outlast several friable stone wheels. As stone wheels decompose they can put a good deal of dust in the air, not to mention that they can break, which is why many use the very large washers on the outside of thinner stones. Although the stone wheels are certainly less expensive one might make the argument that over the long haul the CBN wheel may make up for the initially higher price in longevity, safety, easy care...

[Patrick Chase]

Ray, Patrick answered your question quite well. I will just add that woodturners have been using CBN wheels for sharpening turning tools, often HSS or other hard steels, for a long time now. Turners dull tools fast and most report that they just can't wear CBN wheels out. Another major bonus of CBN wheels is they run much cooler than other grinding materials preventing most over heating scenarios. For "flat" woodworkers these wheels should outlast several friable stone wheels. As stone wheels decompose they can put a good deal of dust in the air, not to mention that they can break, which is why many use the very large washers on the outside of thinner stones. Although the stone wheels are certainly less expensive one might make the argument that over the long haul the CBN wheel may make up for the initially higher price in longevity, safety, easy care...

Mike's absolutely right about heat. More broadly, there are two key metrics that matter to flat woodworkers:

- Grinding efficiency. This measures how much of the power used during grinding is spent removing material versus heating the workpiece. Note however that the efficiency itself varies with grinding rate (generally the faster you go the more efficient, for reasons I'll get to later), so you also need to worry about...

- Absolute rate of heat release. This measures how slowly you can dissipate power into the workpiece while grinding it.

CBN does very well on both metrics. I saw a paper a while back that showed that for production grinding of HSS, CBN wheels are about 3X more efficient than traditional Aluminum-Oxide wheels, and my own experience with lower-speed/temperature work is consistent with that. CBN also runs cool in absolute terms because the sharp abrasives particles cut with very little pressure - you can therefore manage tool temperature by simply using a light touch on the wheel.

The other common choices are friable aluminum-oxide (AlOx) wheels and seeded gel (SG) wheels.

Friable AlOx wheels cut hard tool steels quickly for precisely the same reason as waterstones - they maintain sharpness by releasing grit particles before they can dull or break down. The fact that they continuously expose fresh particles makes friable AlOx wheels both efficient and cool in absolute terms, though not as good as CBN in either respect. They also wear/dish quickly and have to be trued fairly often, again just like waterstones.

SG wheels include some percentage of particles made of an Al-Oxide ceramic, that exposes fresh, sharp edges as it breaks down instead of dulling. The catch is that you have to apply a fair amount of pressure to get those SG particles to break down - if you grind too lightly then the wheel just dulls and glazes and is no better than a conventional AlOx wheel of the same hardness. SG wheels therefore have good efficiency at high grinding pressures, but lower efficiency when used with a light touch. In terms of the metrics I described above they're efficient when used as intended, but not particularly cool-running in absolute terms. In practice you can get around this limitation by either grinding in bursts or by using a low-speed grinder (which allows you to use more pressure without burning the tool). Note that the requirement for relatively high grinding pressure is a property of the SG particles themselves rather than the binder, so softer wheels like the I-grade ones at TFWW only help inasmuch as they make an SG wheel behave more like a friable one, which sort of defeats the point of SG.

FWIW up until about a year ago I used SG wheels, and managed heat by applying pressure in bursts and by using a half-speed grinder. While I hadn't burned a tool in many years with that setup, I now use CBN wheels. They're a LOT more user-friendly.

[Jim Koepke]

I have quite a number of used and fleamarket chisels that need that first reshaping. I think the shaping is more correct term than sharpening.

Most of the time when I have had an old chisel that needs reshaping the back needs a lot of work.

It is difficult for me to imagine having success flattening the back with a bench grinder without doing something that was a major NO, NO when I was taught to use a bench grinder.

Have times and wisdom changed about using the side of a grinding wheel?

I do know having the hollow ground bevel a bench grinder provides is a major help to free hand sharpening. I have been able to free hand without a hollow grind.

For me working the back is easy with abrasive paper on a piece of granite or my flat disk power sharpening system.

jtk

[Patrick Chase]

Most of the time when I have had an old chisel that needs reshaping the back needs a lot of work.

It is difficult for me to imagine having success flattening the back with a bench grinder without doing something that was a major NO, NO when I was taught to use a bench grinder.

Have times and wisdom changed about using the side of a grinding wheel?

You certainly don't want to do that with a conventional vitrified wheel. CBN and diamond wheels are different in that they're turned out of a single chunk of steel so the usual disintegration concerns don't apply. You can even get some with extended sides for exactly this sort of work.

[Mike Holbrook]

Great information Patrick, thanks for providing a better explanation of what is actually happening with CBN abrasive vs other alternatives. My use of CBN wheels has lead me to the same conclusions. I learned early that they cut very well with lighter pressure, simultaneously dramatically reducing the heat produced by removing steel at a relatively rapid rate. It has seemed to me that the grinding pressure /speed necessary to keep heat down while grinding with a CBN wheel is just the speed I find works for making straight, reliable hollow grinds for radiuses etc. by hand.

Jim, I happen to have a CBN wheel that has abrasive on about a 1" band around both sides. I will do a little experimenting with an old chisel to see if I can do flat grinding with that part of the wheel. The challenge I found in doing that on a Tormek wheel is the part of the wheel next to the arbor is rotating faster than the edge 10" from the arbor. Logic would suggest that the speed difference on a 1" band on the outside of a 8" wheel moving at a slow speed might not be as great.

[Ray Selinger]

I wish I heard about CBN before I replaced the wheels on the my two grinders, with soft AO. One is used with the metal lathe the other the wood lathe. Since both are 3450s and bigger at 7" and 8", I chickened out and I ended up using wet/dry to correct my earlier freehand sharpening. The Veil tool rest didn't angle up to 25, so it would have been freehand. The paper was painfully slow and I didn't mess up that badly. There has to be a better way. The fleamarket chisels are very different story.

[Patrick Chase]

I wish I heard about CBN before I replaced the wheels on the my two grinders, with soft AO.

I wouldn't worry about it. A lot of people here use CBN wheels and are vocal about how great they are (as I was above), but IMO CBN wheels remain a luxury item as opposed to a must have. Soft AO wheels (vitrified grade H bond or thereabouts) get the job done very nicely and aren't all that demanding in terms of user technique. Just keep the pressure light, rest the tool whenever it gets warm (I shoot for "never uncomfortable to touch, even at the tip"), and dress/true them when needed.

[Derek Cohen]

What is a CBN wheel? This is a good discussion, I have quite a number of used and fleamarket chisels that need that first reshaping. I think the shaping is more correct term than sharpening.

Hi Ray

I posted this article here about a year ago, and updated it a few months later: http://www.inthewoodshop.com/WoodworkTechniques/UltimateGrindingSharpeningSetUp.html

There are illustrations of the wheels and how I use them (others will do so differently, with much success - in other words, lots of room for variation). There are a couple of links to suppliers, as well as tips what to watch out for.

Regards from Perth

Derek

[Ray Selinger]

Thanks Derek. That explains using CBN wheels very well. One of yesterday's antique store finds was a Geo. V.& H. Stormont Sheffield (pre 1948) firmer chisel. A pitted candidate for some trials. I find this English chisel design is interesting, not bevel edged but thin and light with the standard English handle.

When sharpening with the water stones I use thin disposable nitrile mechanics' gloves. In my case, to prevent sharpening my fingers, they bleed.

[george wilson]

CBN may be the hardest man made abrasive,but if you look at a scale of hardnesses represented by vertical pillars,it is NO WHERE NEAR the hardness of diamond. I think it costs way too much as compared to diamond. The trouble is,you need a VERY SLOW RPM like my diamond sharpener(200 RPM),or the carbon in the diamonds will go into the steel,making the diamonds wear out,and making stuff like HSS too brittle.

So,I guess you're stuck with using CBN wheels on your ordinary speed bench grinder. I haven't gotten a CBN wheel because of the cost (Vs. getting REAL diamond coated wheels for my 200 RPM grinder) ,and my Square Wheel belt grinder will grind steel away faster than any bench grinder can. I have used it to grind knives from the solid,and other grinding projects that need removal of a LOT of steel.

The Square Wheel grinder costs too much for a lot of home shop guys to afford($2000.00+),But Grizzly makes a belt grinder for knife makers that ought to be just fine,except I like the enclosed belt on mine for keeping steel dust from floating around. If I HAD to use the Grizzly,I'd make an enclosure for the belt.

[Patrick Chase]

CBN may be the hardest man made abrasive,but if you look at a scale of hardnesses represented by vertical pillars,it is NO WHERE NEAR the hardness of diamond. I think it costs way too much as compared to diamond. The trouble is,you need a VERY SLOW RPM like my diamond sharpener(200 RPM),or the carbon in the diamonds will go into the steel,making the diamonds wear out,and making stuff like HSS too brittle.

These are both true but perhaps incomplete.

CBN is about 2/3 as hard as Diamond, but they're both so far enough above anything you would realistically sharpen that hardness isn't a limiter anyway (the hardest carbides are about half as hard as CBN). In practice the abrasive-to-wheel bond is more of a limiter. Also if your Ebay disks use polycrystalline diamonds then the effective hardness is reduced quite a bit anyway as the particles will fracture at much lower loads :-).

The Carbon migration you describe happens at 700C (1300F) and above. If you do heavy production grinding of HSS to the point where it's red-hot then this is a real concern (and that's why CBN wheels are so pervasive). It's a nonissue for flat woodworkers using tool steel because by the time the carbon migrates you will have long since destroyed your tools. For that matter it's also a nonissue for most turners as well because even they don't generally grind their tools that hot.

EDIT: I decided to check my recollection and saw your thread on Practical Machinist from 2011 (that is you, right?). The bit about the presence of a spark proving that the temperature is high enough is wrong. The *diamond* must reach 700C for migration to occur, but the presence of a spark only indicates that the *steel* has been locally heated. Deforming a material (the steel in this case) creates heat, and the material being deformed therefore becomes much hotter than the material doing the deforming. I'll grant that the diamonds probably do reach 700C a bit before the steel reaches red heat though.

The problem with documentation on manufacturer's sites like Norton is that they invariably deal with high-duty-cycle production grinding.