Flattening a Hard Silicon Carbide Honing Stone

[Steve Voigt]

Nobody bothered with flattening until the new sharpening came along to make things difficult - the main motivation being the opportunity to sell loads of kit, DVDs , courses, articles.
As you say; "pay attention to the edges and the corners and the middle will get done".

This is simply not correct. The original text of "The Joiner and Cabinetmaker" (1839) refers to workmen being fined for not flattening their stones. Charles Hayward, who learned his craft 100 years ago, warns strenuously about the dangers of not flattening stones, and gives a method (builders sand on a flagstone) that is not that different from what Stewie is doing.

Flatness is not the only consideration: dressed stones cut much more rapidly. I'd rather not be at the sharpening station all day.

Regarding your earlier comment that flattening "severely shortens the life of a stone," I must say that I flatten my stones every week or two, but I expect I will be dead before my stones are too thin to use.

A couple other comments on this thread. Charlie referred to spending $300 to flatten a $20 stone. No doubt using the DMT on a Crystolon was pretty boneheaded, but it doesn't have to be that way. I bought 2 pounds (probably a lifetime supply) of 60-80 grit SiC for about $15, shipping included. I went to the local glass place to buy a remnant and they gave me one for free. So, you can spend less than $20. Amortized over hundreds or even thousands of flattenings, that works out to pennies per session.

Also, I have to agree with Ed's "If your priorities are different that's fine, but please don't pontificate to us who have a different set." For example, part of my living involves preparing irons and shipping them to others. I need to be able to tell someone honestly that I flattened the back on a flat stone. If they want to use a hollowed stone, that's fine, but I need to have some kind of consistent reference or starting point.

Last, while I obviously believe in flattening stones, I think I wouldn't have done so here. I don't have personal experience with Crystolon stones, but I know they are very hard and consequently difficult to flatten. At $20 per pop, I'd treat the stone as disposable, and just get a new one every few years. On the other hand, India and Arkansas stones are very easy to flatten.

 

[Phil Pascoe]

Welcome Steve, fair comment. "Pay attention to the edges and the corners and the middle will get done" was my comment originally - I did not suggest it as a universal panacea, just a help in postponing the inevitable. Whether or not anyone thinks the inevitable worth a nanosecond's thought is secondary.

 

[Phil Pascoe]

:lol: ... Actually, flattening the stone isn't going to shorten its life by a second - wearing it hollow in the first place is. You are not going to flatten it beyond the point up to which you wore it hollow. :lol:

 

[Jacob]

.....
Flatness is not the only consideration: dressed stones cut much more rapidly. I'd rather not be at the sharpening station all day.
......

Yes they do need refreshing. I use a 3m Diapad. Slightly bendy so it follows the dips. Just a quick pass (with white spirit or thin oil) and a wipe, every now and then.

 

[woodbrains]

Nobody bothered with flattening until the new sharpening came along to make things difficult - the main motivation being the opportunity to sell loads of kit, DVDs , courses, articles.
As you say; "pay attention to the edges and the corners and the middle will get done".

This is simply not correct. The original text of "The Joiner and Cabinetmaker" (1839) refers to workmen being fined for not flattening their stones. Charles Hayward, who learned his craft 100 years ago, warns strenuously about the dangers of not flattening stones, and gives a method (builders sand on a flagstone) that is not that different from what Stewie is doing.

Flatness is not the only consideration: dressed stones cut much more rapidly. I'd rather not be at the sharpening station all day.

Regarding your earlier comment that flattening "severely shortens the life of a stone," I must say that I flatten my stones every week or two, but I expect I will be dead before my stones are too thin to use.

A couple other comments on this thread. Charlie referred to spending $300 to flatten a $20 stone. No doubt using the DMT on a Crystolon was pretty boneheaded, but it doesn't have to be that way. I bought 2 pounds (probably a lifetime supply) of 60-80 grit SiC for about $15, shipping included. I went to the local glass place to buy a remnant and they gave me one for free. So, you can spend less than $20. Amortized over hundreds or even thousands of flattenings, that works out to pennies per session.

Also, I have to agree with Ed's "If your priorities are different that's fine, but please don't pontificate to us who have a different set." For example, part of my living involves preparing irons and shipping them to others. I need to be able to tell someone honestly that I flattened the back on a flat stone. If they want to use a hollowed stone, that's fine, but I need to have some kind of consistent reference or starting point.

Last, while I obviously believe in flattening stones, I think I wouldn't have done so here. I don't have personal experience with Crystolon stones, but I know they are very hard and consequently difficult to flatten. At $20 per pop, I'd treat the stone as disposable, and just get a new one every few years. On the other hand, India and Arkansas stones are very easy to flatten.

Hello,

Sensible fellow, I like this chap from his first post, I hope it continues!

Mike.

 

[Trafalgar]

"Last, while I obviously believe in flattening stones, I think I wouldn't have done so here. I don't have personal experience with Crystolon stones, but I know they are very hard and consequently difficult to flatten. At $20 per pop, I'd treat the stone as disposable, and just get a new one every few years. On the other hand, India and Arkansas stones are very easy to flatten."

Yep. Not really even worth fooling with should they become glazed and/or slower than one might prefer, much less out of flat. India stones, maybe, but they're just as inexpensive ($19) -- which is good news, not bad.

 

[swagman]

Charles; you have acquired an inept ability to cherry pick comments that fall within your own agenda; the following is the full version of what Steve Voigt stated;

Jacob wrote:

Nobody bothered with flattening until the new sharpening came along to make things difficult - the main motivation being the opportunity to sell loads of kit, DVDs , courses, articles.
As you say; "pay attention to the edges and the corners and the middle will get done".

Steve Voigt:

This is simply not correct. The original text of "The Joiner and Cabinetmaker" (1839) refers to workmen being fined for not flattening their stones. Charles Hayward, who learned his craft 100 years ago, warns strenuously about the dangers of not flattening stones, and gives a method (builders sand on a flagstone) that is not that different from what Stewie is doing.

Flatness is not the only consideration: dressed stones cut much more rapidly. I'd rather not be at the sharpening station all day.

Regarding your earlier comment that flattening "severely shortens the life of a stone," I must say that I flatten my stones every week or two, but I expect I will be dead before my stones are too thin to use.

A couple other comments on this thread. Charlie referred to spending $300 to flatten a $20 stone. No doubt using the DMT on a Crystolon was pretty boneheaded, but it doesn't have to be that way. I bought 2 pounds (probably a lifetime supply) of 60-80 grit SiC for about $15, shipping included. I went to the local glass place to buy a remnant and they gave me one for free. So, you can spend less than $20. Amortized over hundreds or even thousands of flattenings, that works out to pennies per session.

Also, I have to agree with Ed's "If your priorities are different that's fine, but please don't pontificate to us who have a different set." For example, part of my living involves preparing irons and shipping them to others. I need to be able to tell someone honestly that I flattened the back on a flat stone. If they want to use a hollowed stone, that's fine, but I need to have some kind of consistent reference or starting point.

Last, while I obviously believe in flattening stones, I think I wouldn't have done so here. I don't have personal experience with Crystolon stones, but I know they are very hard and consequently difficult to flatten. At $20 per pop, I'd treat the stone as disposable, and just get a new one every few years. On the other hand, India and Arkansas stones are very easy to flatten.

 

[Biliphuster]

Welcome Steve, fair comment. "Pay attention to the edges and the corners and the middle will get done" was my comment originally - I did not suggest it as a universal panacea, just a help in postponing the inevitable. Whether or not anyone thinks the inevitable worth a nanosecond's thought is secondary.

I have a couple of oil stones which I have managed to crown by using the edges and ends to sharpen chisel and plane bevels and using the whole stone for removing the burr. So far I have noticed no ill effects, in fact I am convinced there are a couple of advantages to using a stone which is higher in the middle.

 

[Jacob]

......
Jacob wrote:

Nobody bothered with flattening until the new sharpening came along to make things difficult - the main motivation being the opportunity to sell loads of kit, DVDs , courses, articles.
As you say; "pay attention to the edges and the corners and the middle will get done".

Steve Voigt:

This is simply not correct. The original text of "The Joiner and Cabinetmaker" (1839) refers to workmen being fined for not flattening their stones.

You shouldn't take as gospel everything you read in books. This is just an isolated anecdote. No doubt some were strict about all sorts of things.

Charles Hayward, who learned his craft 100 years ago, warns strenuously about the dangers of not flattening stones, and gives a method (builders sand on a flagstone) that is not that different from what Stewie is doing.

Hayward does not "warn strenuously" - again it's just another anecdote. Anybody who tries "builders sand on a flagstone" is going to be at it for a very long time, not least looking for flat flagstones and replacing them as they get hollowed out! The advice is usually for silver sand which is a lot sharper than builder's. It'd work as a means of cleaning up an old stone and refreshing the surface, but be no good for the modern obsessive flatteners.

The main evidence for not needing to flatten is:
1 that most old stones are not flat. I don't really believe that nobody knew how to sharpen properly until the modern sharpening fashions kicked in!
2 If you "flatten" your stones in use, by spreading the work carefully, you will never need to do it as a separate operation. NB they don't need to be perfectly flat, but phil.p's advice "pay attention to the edges and the corners and the middle will get done" is well worth remembering.

PS and nobody used to flatten the whole surface of plane blades or chisels, like the modern obsessives. Just the usual taking off the burr results in a slight flattening of the edge half inch or so, and this is all that's needed.
Buying expensive diamond plates for flattening stones is crazy - you'd be much better using them to sharpen tools.

 

[bugbear]

1 that most old stones are not flat.
2 If you "flatten" your stones in use, by spreading the work carefully, you will never need to do it as a separate operation.

We can therefore conclude from (1) that the anonymous craftsman of old were ignorant of (2).

BugBear

 

[swagman]

The main evidence for not needing to flatten is:
1 that most old stones are not flat. I don't really believe that nobody knew how to sharpen properly until the modern sharpening fashions kicked in!
2 If you "flatten" your stones in use, by spreading the work carefully, you will never need to do it as a separate operation. NB they don't need to be perfectly flat, but phil.p's advice "pay attention to the edges and the corners and the middle will get done" is well worth remembering.

Jacob; by your own reasoning; no.2 has to be a fairly modern practice. (hammer)

Stewie;

 

[bugbear]

The main evidence for not needing to flatten is:
1 that most old stones are not flat. I don't really believe that nobody knew how to sharpen properly until the modern sharpening fashions kicked in!
2 If you "flatten" your stones in use, by spreading the work carefully, you will never need to do it as a separate operation. NB they don't need to be perfectly flat, but phil.p's advice "pay attention to the edges and the corners and the middle will get done" is well worth remembering.

Jacob; by your own reasoning; no.2 has to be a fairly modern practice. The basis behind your own argument is as hollow as the stones you choose to use. :roll:

Stewie;

Actually, from a photo Jacob once posted, we know the stones he actually uses are flat. He's just arguing for the sake of it.

We also know that Jacob isn't a tool collector, and doesn't bother going to auctions or car boots sales, or tool dealers, he's too busy getting on with woodwork.

So his claims about what old kit he's seen, and how representative it might be, should be viewed accordingly.

Symmetrically, were I to make any statements about making sash windows with power tools, they should be treated with extreme caution.

BugBear

 

[Trafalgar]

The whole debate is ridiculous, as was ruining an expensive diamond stone to rescue a dirt cheap stone and then leaving the impression that one would do it all over again without batting an eyelash. Lop the nose off to spite the face. Rinse, then repeat.

Man-made oilstones are an extraordinary value in a hobby or profession where most things are very expensive. If one finds fault for whatever reason, they are easily replaced at a very low absolute cost and certainly when compared to other stones and paper abrasives.

Dished stones can still be used. Rarely are both sides dished in the first place should one desire a full, flat side. Or, buy a new one for the cost of a beer and cigarette run to the grocery store. The old stone can be cleaved and ground to shape(s) to make little files and mini-hones if you need a project for a rainy afternoon.

 

[D_W]

Of all of the stones out there, a crystolon type stone is one to keep flat in use by overlapping corners and edges.

A new one is nice to have once in a while, anyway, because they get hard as they get old.

Some of the finer grit older bench stones are available on ebay for a couple of dollars. Some unused and still factory flat.

 

[Jacob]

1 that most old stones are not flat.
2 If you "flatten" your stones in use, by spreading the work carefully, you will never need to do it as a separate operation.

We can therefore conclude from (1) that the anonymous craftsman of old were ignorant of (2).

BugBear

Confused BB, as ever! :lol:
I'll explain carefully - read this slowly: you don't need to flatten stones as a separate process if you keep them flat enough by careful use, as was always the way before the modern sharpening craze kicked in.

...
Actually, from a photo Jacob once posted, we know the stones he actually uses are flat. ....

I once posted a photo of a newish stone in use. This confused BB (as usual :lol: :lol: ) into thinking I had flattened all my other stones too. No logical connection but there you are. :roll:

 

[swagman]

The whole debate is ridiculous, as was ruining an expensive diamond stone to rescue a dirt cheap stone and then leaving the impression that one would do it all over again without batting an eyelash. Lop the nose off to spite the face. Rinse, then repeat.

Charles; that is a load of malarkey; go back and read my opening post; its premised on the best method to flatten a hard Crystolon stone; a diamond stone wont do it; but loose sic powder over a glass plate will.

 

[D_W]

The whole debate is ridiculous, as was ruining an expensive diamond stone to rescue a dirt cheap stone and then leaving the impression that one would do it all over again without batting an eyelash. Lop the nose off to spite the face. Rinse, then repeat.

Charles; that is a load of malarkey; go back and read my opening post; its premised on the best method to flatten a hard Crystolon stone; a diamond stone wont do it; but loose sic powder over a glass plate will.

Loose SIC larger than the stone particles. Smaller SIC will grade the surface of the stone, and if it's an older stone that has gotten hard, it'll be hard to recover the cutting power of the stone.

 

[Steve Voigt]

You shouldn't take as gospel everything you read in books. This is just an isolated anecdote. No doubt some were strict about all sorts of things.

It's not an isolated anecdote. Holtzapffel, vol.3 (1850), p.1142, agrees that "even distribution of wear" is important, but then says that stones occasionally need to be flattened. David Denning (1891), p.102, prescribes emery or sand on a level board. There's another reference from the same period that I unfortunately can't put my hands on at the moment.

And I don't believe everything I read in books, but I'll believe a reputable old book before I'll believe some guy on the Internet, any day.

Hayward does not "warn strenuously" - again it's just another anecdote. Anybody who tries "builders sand on a flagstone" is going to be at it for a very long time, not least looking for flat flagstones and replacing them as they get hollowed out!

Seriously, you want to argue about whether my use of "strenuously" was correct, and whether Hayward's method was effective? Let's stay on track, shall we? I was responding to your claim that "nobody flattened stones until the new sharpening came along" (whatever that means). Clearly Hayward is refuting your claim; whether you think it was strenuous enough is beside the point.

The main evidence for not needing to flatten is:
1 that most old stones are not flat. I don't really believe that nobody knew how to sharpen properly until the modern sharpening fashions kicked in!

Most old saws that I find are completely dull and have random geometry, unequal tooth height, and too much set. Should we therefore maintain our saws this way, because that's what "users in the past" did? (It's a rhetorical question)

If we're going to look to the past to decide how best to use our tools, we should look to an era when people used hand tools for most or all things, and when hand tool skills were strong. But when you find an old oilstone at garage (or "boot") sale, on Ebay, or wherever, It's unlikely that Duncan Phyfe was the last guy to use it; it was probably used by some guy in the 20th century who didn't have much or any expertise. So you really can't draw any conclusions about what competent 18th/19th c. users did by basing your observations on tools that were abused by hacks in the 20th century. If you can find a bunch of stones that were owned by skilled workers before the 20th c., and if you can prove that they haven't been used since, then you might have some useful data. Right now, you don't. You be a lot better off looking at those old books that you so disdain.

 

[D_W]

I just went out to ebay out of curiosity to look at the sharpening stone "lots". They're always littered with carborundum and india stones because machinists bought those and cast them aside when they loaded (probably put in a purchase order for a new one). It didn't take long to find a lot of 8 stones for $8 (shipping brought the total up to $19), four of them were 2x8 and 2x7 carborundum stones, the other four were small stones and scythe stones.

There are gobs of those lots on ebay. 6 or 7 years ago, I got a sale lot of stones because I wanted slips and triangles from it. When I got the lot in the mail, there were so many different bench stones in it (some of them interesting tries at an india type stone with a stinky mud binder) that it must've been less than a dollar a pound for them when all was said and done. I slipped the india stones in boxes of stuff I've sold over the years, and kept the interesting stones.

Flip side of that, I think it's useful to keep a pound or two of 60 grit SiC around, sooner or later you'll find a user for it and it doesn't matter if it's in two decades when you do.

(but like i mentioned above, keeping a silicon carbide stone flat is sort of a lost cause other than functionally flat - they are friable, or if they are no longer friable, they load quickly, and they're not good for backs. They are the best stone anywhere for coarse bevel work and cleaning up a knife that's got some damage. FAR better than diamond hones, far cheaper, and the result on the edge is far cleaner without deep scratches...and they're faster on knives and most chisels).

 

[Trafalgar]

One can easily back off a cutter on a stone with a profound swale. You just use the areas at the end that are still flat, which is precisely what the previous user would have done (you actually can do it in the swale from side to side if you're careful). There is no need to run the flat face, lengthwise, on the stone practically from end to end. They were likely never flat enough for this sort of technique to begin with. If you started out with a cutter with a pretty flat back and now it's not so flat, this very thing is likely the cause or at least one of the top three suspects.

The old saws mentioned in a previous post were likely ruined by users from the 1940s onward, and have little to do with honing stones. You can ruin a saw in a couple of sharpenings (It usually only takes me one time to ruin one :wink: ). It takes years to put a decent swale into a stone, even a man-made stone. The chance that some amateur working in a garage a weekend or so out of the month could do it is pretty remote. That leaves stones with a pronounced swale coming out of some sort of professional shop, or a busy but capable amateur's. And a lot of stones on EBay, natural and man-made, have this very "flaw."

All this said, it's pretty easy to keep one flat (to the naked eye kind of flat, not to a machine room grade spec). You just use the whole surface, and of course, both sides.