Cambered irons and hollowed stones...

Sounds reasonable to me...

Dave (Arlington, VA)

>Hi Joe -

Creative thinking and an interesting observation! I'll be looking forward to seeing what others say.

Regards -

Dave

So what you're saying is....

Steve Kubien

>...that I may no longer have need of the 3/4" thick slabs of glass I recently acquired (very gloatable price---free) for my sandpaper sharpening methods and I can go to water or oil stones without free of wrecking them?

I too will be following this thread. Nice bit of reasoning.

Steve Kubien

Ajax, Ontario

Re: So what you're saying is....

Joe Rogers, Northern Virginia

>Quite possibly.

I have mostly natural(Arkansas)oilstones in my arsenal. I also have a well dished Crystolon(sp) stone inherited from my dad. He was an artist and wood carver. He was able to get razor edges on his chisels. With this well worn carborundum. I don't know if this thought is true or not about cambered blades but I was just thinkin...specially since this pre hollowed diamond plate has appeared. I'm kinda hoping great thinkers here can poke holes in my theory . If I'm right it might set a bad example. :-)JR

Not so fast

Adam Cherubini

>Just from a practical standpoint, I think we're still stuck with flat stones for backs at least. I must admit that a fair amount of my sharpening time is restoration- maybe just because it takes so long.

Re: Not so fast

Joe Rogers, Northern Virginia

>Depending on the extent of the back that was flattened in days of yore coudn't they just use the end of the stone where it isn't dished? How much of the blade backs were worked then? If it was just a 1/4" or a 1/2" it seems workable to me.JR

Toshio Odate

Frank D. in Montreal

>If I'm not mistaken it was Toshio Odate had the diamond plate developed. He also wrote several years ago about Japanese Shokunin using a *very slightly* dished stone to get a camber. It all depends on just how much camber you want and whether you can trsut your stone to keep that camber (I guess oil stones keep their shape a lot longer). I've been using camber to my advantage since I read Odate. I start with the blades I want straight, then toward the end of my sharpening session I do the blades that I want a slight curve to. I use water stones though so I still have to flatten them often, and I don't want a real big curve on most of my blades anyways. If you look at the concave diamond plate we're talking thousandths. Using a totally dished stone might also add more difficulty to sharpening than it would help. The curve would have to be pretty even, and along the width; curve along the length would round over the edge it seems to me.

Just a few thoughts,

Frank

Re: Cambered irons and hollowed stones...

Adam Cherubini

>Joe,

I considered that most of the stones found in old kits were hollowed also but in the narrow dimension.

The hollow stones we find may be the result of hacks or knife sharpeners. We mustn't assume this is the way these stones always were. But I think you're right.

I think that this produced a cambered iron because the normal stroke was with the blade at an angle to the stone...not perpendicular to the length. With reversal of the blade from one skew to the complementary angle the camber will be a natural result.

Actually, a skewed blade on a dished stone will naturally camber. No need to reverse the skew angle. The leading edge gets dubbed on the push or pull.

Backing off the wire edge could be done on the edge or end of the top surface where the stone remains flat.

Or on another stone? Or stropped off?

I think the old timers didn't have flat stones because they didn't need them. They also were skilled enough to produce a flat back when necessary.

I don't see alot of flat backs on old tools. Again, we can't know if this was the result of abuse or not. Some tools, like molding plane irons, seem less flat than others.

Straight honed plane blades...didn't need them or use them.

I disagree. They certainly did need them. But the point is moot because by holding the blade perpendicular to the stone, you can achieve a straight edge.

I'm not sure if I mentioned this before, but I'm very interested in this subject and have given it some thought. I feel as though the pieces of the puzzle are here, but I just can't see the image. Forgive me, I've had a tough week, but sometimes I feel like our Grandfathers are trying to tell me/us something. I am in no way convinced that we have a better system of edge tool making or sharpening. It all just seems so complicated. They must have had sharp tools to do what they did, yet their sharpening media was junk by modern standards.

So I think you're on to something, Joe. I promised Jeremy that if he came to Pennsbury, we would practice free hand sharpening with period stones and period chisels. I'm sticking with that. Pretty sure you have to keep the steel and the stones in sync- no A2 or CPM with these materials/methods.

Otherwise, I'm doing what you all are doing- i.e. sharpening on glass with as high tech stuff as I can get. But the voices tell me there's an easier way. Of course the voices also tell me to dress up as a clown and murder people, so there's that.

Adam

:-)

Joe Rogers, Northern Virginia

>Clown suits. Now there is something I can help with. My mother used to be in the circus.True!JR

Re: Cambered irons and hollowed stones...

Warren in Lancaster, PA

>I do two things to avoid hollowing the stones. First I use a separate set of stones for small chisels, carving tools, and turning tools-those more likely to wear a hollow. Second for all tools I try to use the whole stone and go over the edges. Even so the stones eventually become too hollow for plane irons.

It is true that the fact that I use cambered irons means I can tolerate a slight hollow in the stone, but I think a newly flattened stone gives the most control and best results. If the stone is higher at the ends than the middle, it is harder to keep a consistant bevel. If the stone is flat from side to side it is easier to conrol the amount of curvature on the edge. It is always a joy to use a stone that was just flattened.

Re: Cambered irons and hollowed stones...

Todd Hughes

>I guess I was lucky because when I started out slow head me never knew that my sharpening stones had to be perfectly flat to get a sharp edge. Not knowing any better I just use my old stones that have a slight dip in them like you see and I get edges sharp enough to shave with pretty easly. I sharpen the blades in a sort of figure 8 pattern or go from one corner to the other diagonaly if with a wide blade and can't see how a slight dip would affect anything...the blade just rides over the dip.Actually with use the stone should tend to wear pretty flat though truthfully I never fool to even check to see....not important to me. Maybe if the stone had say a 1/2 in. dip it might affect something but I never felt the need to worry about just a slight dip.....Todd

Clown Suits

Steve Elliott

>There's something I can speak of from experience. Here's the proof:

I've outgrown that one, but some days I think I should still be wearing one.

Re: Cambered irons and hollowed stones...

Joel

>If you were correct then when Arkansas stones came on the market (c. 1850) people would not have rushed to buy them and driven other sharpening stones out of the market because the advantage of a dish stone would be lost.

But they did rush to Arkansas stones.

they also had no simple way of flattening arkansas stones. but since it takes years for a good one to dish they didn't have to worry so much. Most of the dished old stones I have seen have been clearly not in a cabinet shop any time recently - actually I would say 99 percent of the old stones we see at flea markets were never used for cabinetmaking in the first place. Razor and pen knive sharpening by mostly amatures. IIRC the old stones I have seen found in provenounced toolboxes that we never abandoned to be used randomly were pretty flat.

maybe no as flat as what you get with hours of worrying about it but certainly flat enough.

I think once you have the technique of sharpening down you worry less about whether something is flat or not. You can eaisly tell when you sharpen if the system is working right - and if it's not you can compensate.

Say that again Joel

Todd O. Cronkhite Maine Native in FL. Exile :~(

>IIRC the old stones I have seen found in provenounced toolboxes that we never abandoned to be used randomly were pretty flat.

I didn't understand this sentence. I looked for provenounced in the dictionary but it wasn't there.

Todd O.

Re: Say that again Joel

William Duffield, on the Cohansey

>Provenance is an unbroken history of ownership of the antique item, in this case the toolbox and its complete, catalogued contents. Joel means that we know from this history that the tools in the box were always used by skilled craftsmen to the original intent of the tool, or that they have laid unused since laid down by the original craftsman. More importantly, it means we know the stones weren't ever used for sharpening bulldozer bucket teeth, or smashing bugs or driving nails, or to prop up a washing machine foot, other random abuses.

Re: Cambered irons and hollowed stones...

Greg B

>Just curious about the source of the reference to hollowed stones. I haven't seen the PW article, but using a hollowed stone, in either direction, doesn't sound like something David would recommend. Maybe it's more of an editor's aside/guess, but maybe not.

David's methods, both learned from others and developed on his own, seem to be the result of a certain kind of evolution. The aim is a combination of precision and repeatability. This explains the use of honing guides, for example. He also routinely warns against the waterstones getting out of flat. With a flat stone, you know exactly where you are and can apply point pressure where you want to, on the way to your desired result. You dictate to the iron, rather than the stone doing so. An out-of-flat stone introduces an extra variable to the equation and would, I suspect, complicate matters for the sharpener. (not to mention the question of creating the right hollow shape, both in width and length, stone-to-stone) This sounds counter-Charlesworth to me.

I wonder if our forebears simply were skilled enough and practiced enough to make a stone work despite it being out-of-flat. In other words, making due with a sub-optimal stone rather than throwing it away. I wonder what they would have done with water stones and a quick method of returning them to flat once they became a little dished. In that case, would the old stones we find still be as hollowed as these oilstones?

Re: Cambered irons and hollowed stones...

Dan Clermont

>I will sometimes use a hollowed stone to my advantage and sharpen a cambered blade with it before reflattening it.

I think that we have all become used to the easy to flatten Japanese stones compared to the arkansas stones which require more effort.

We also tend to use planes manufactured to higher tolerances and try to create air tight joints whereas our forefathers were more concerned about making enough furniture to feed the family.

Dan Clermont

Re: Cambered irons and hollowed stones...

paul womack

>In "the Village Carpenter" by Walter Rose

http://www.wendoverbookshop.co.uk/rural/rose.village.htm

http://nika.frontier.iarc.uaf.edu/~cswingle/archive/get.phtml?message_id=58354#message

He says:

It is easier to sharpen a true edge on a wide tool with a narrow stone than with a wide one".

He argues this because it's difficult to keep a wide stone flat across it's width. This appears to imply that a straight edge is desired, and a flat stone to create it is desirable, but difficult to attain.

BugBear