Did oldtime craftsman flatten their plane irons?

[Judson Green]

My best answer on this is a question.

Was a flat back needed on a single iron plane?

If a cap iron (a.k.a. chip breaker) was involved, did anything other than a flat back prevent the shavings constantly clogging between the cap iron and the blade?


jtk

yes just the thing i was wondering

[Andrew Pitonyak]

Although it strikes me as an interesting question in its own right (did they flatten the backs), I think that Mr. Cohen alluded to what matters; what works best (he actually said something about an improved regiment).

I suspect that some of us (<cough> <me> <cough>) go beyond what is required in some areas (like using a 16000 Shapton), and, in some instances, that might even be counter productive (like when sharpening a kitchen knife).

Great thread!

[Frederick Skelly]

Here's a question or three: if you come to the conclusion that cabinetmaker's of yesteryear honed the bevel alone and "sort of" removed the wire, without any effort to work the back of the blades .... would you change your current sharpening regimes and do the same?

In the same vein, knowing that oilstones probably do not go above the equivalent of a Japanese waterstone rated 6000 grit, would you stop honing above this level (whatever you use)?

Perhaps you are reluctant to change what you do. Is this because you do so out of habit, or because you believe that a modern day sharpening regime is superior to one from yesteryear?

Regards from Perth

Derek

Hello Derek!
Those are all logical, "cut to the quick of the matter" questions. Since I started the thread, I thought I'd answer from my personal perspective.....

Answer #1: Would I change my current regimen? Personally, if the oldtimers' regimen was shorter/simpler, I'd certainly give it a try to see if it worked for me. I truly hate flattening old plane irons, but I also feel a bit sacriligous (sp?) using new irons in old planes. So I flatten. (Sigh)

Answer #2: I currently hone to "only " 6000 and periodically consider buying a much finer stone. So if the oldtimers went no higher, that might convince me what I have is sufficient. Today I was pulling shavings thicker than many of you routinely get (mine were "only" 0.002 inch).

Answer #3: I'm not reluctant at all. I've tried many of the suggestions in other sharpening threads. But I'm coming to realize that, like anything else, it's possible (for me anyway) to get carried away. So my original question was partly pure curiousity and partly a way to gauge what's "good enough".

Best regards,
Fred

[Jim Koepke]

Today I was pulling shavings thicker than many of you routinely get ( mine were "only" 0.002 inch).

I know I always bring up the ultra thin shaving stuff, but I am often taking thicker shavings.

Today I was using a router plane and I have the adjustment marked. The bolt is 18 threads per inch. The nut is divided into 8ths. An 8th of a turn makes about 0.007" advance on the blade. Sometimes I would advance the blade about 1/4 turn of the nut for a 0.014" shaving.

When I was working on a #3 rehab the other day after setting it for the sub thou shavings it was set to take shavings that measured 0.021". I call those zipper shavings because that is not only how the sound when being made, but they have ripples running from side to side.

jtk

[Frederick Skelly]

"Zipper shavings" - that's a great name for them Jim. I often get those when I take a slightly too thick shaving with my camfer plane. (Which, by-the-way, still ROCKS - I'm sooo glad you got me interested in making one of those!)

Fred

[Patrick Chase]

Over on the ukworkshop forum there is a guy named Jacob. He is running a holy war against flat backs on chisels and plane irons. He never gets tired of learning everyone around that flattening backs is a modern fad.

I would agree with him if I didn't alwas acquire irons with pitting and heavy dubbed edges on the back. So I continue polishing backs, but keep my efforts centered on the last 1/2" or so.

I think that some people conflate "flat" and "smooth". There is also the question of "local flatness" vs the sort of overall flatness that LN and LV now achieve.

IMO smoothness matters a lot - you can only have a truly sharp edge when two smooth surfaces intersect. If either surface is rough then the edge will be ragged in equal degree. Note that I say "smooth surfaces" where many authors instead say "smooth planes". Planarity (a.k.a. "flatness") doesn't impact sharpness. Also, the amount of the edge that needs to be smooth is very small - all that matters is that scratches don't compromise the edge.

Local crosswise (parallel to the cutting edge) flatness immediately behind the edge is critical in anything with a double iron. If you don't have at least that then good luck getting the cap iron to mate well enough to avoid clogging. Charlesworth's "ruler trick" is basically taking advantage of this fact - he dubs the face a bit lengthwise while preserving crosswise flatness.

Beyond that it's a matter of degrees, specifically whether the blade is out far enough to compromise cut depth/profile or prevent bedding with a reasonably tight cap iron (though note that in a BD plane this is more a function of the back than of the face). IMO you absolutely do not need total flatness for either of those.

So taking all of that together, I don't spend much effort flattening blade faces other than in the immediate vicinity of the edge. When I encounter a non-flat blade my usual reaction is to reach for a thicker ruler (or piece of shim stock), within reason. I appreciate the flatness of my LV/LN blades, but also recognize it as a form of market-driven fetishism that doesn't really impact performance.

[Stanley Covington]

I think that some people conflate "flat" and "smooth". There is also the question of "local flatness" vs the sort of overall flatness that LN and LV now achieve.

IMO smoothness matters a lot - you can only have a truly sharp edge when two smooth surfaces intersect. If either surface is rough then the edge will be ragged in equal degree. Note that I say "smooth surfaces" where many authors instead say "smooth planes". Planarity (a.k.a. "flatness") doesn't impact sharpness. Also, the amount of the edge that needs to be smooth is very small - all that matters is that scratches don't compromise the edge.

Local crosswise (parallel to the cutting edge) flatness immediately behind the edge is critical in anything with a double iron. If you don't have at least that then good luck getting the cap iron to mate well enough to avoid clogging. Charlesworth's "ruler trick" is basically taking advantage of this fact - he dubs the face a bit lengthwise while preserving crosswise flatness.

Beyond that it's a matter of degrees, specifically whether the blade is out far enough to compromise cut depth/profile or prevent bedding with a reasonably tight cap iron (though note that in a BD plane this is more a function of the back than of the face). IMO you absolutely do not need total flatness for either of those.

Patrick:

A well stated common-sense approach.

I would add that, as much as we try, it is practically impossible to obtain true planar flatness using imperfect stones and irregular hand movement, which is the best we have to work with. It is difficult even with very precise machinery. As much as we want perfection (or not as in the case of the flaming anarchists), the best we can hope to achieve is a compromise between sharpness and speed. For woodworking purposes, and where stropping is used (a procedure I follow religiously) close is good enough, IMO.

My argument has been that, while the old timers in the West had unimpressive stones, their surviving work is testimony that they knew how to get a pretty sharp edge, and the more accomplished of them would know enough to try to keep their stones flat and their blades (at least the last few millimeters of the blade) relatively flat and with uniform scratches. Efficiency would demand this much of their attention at least.

Two cents.

Stan

[Patrick Chase]

My argument has been that, while the old timers in the West had unimpressive stones, their surviving work is testimony that they knew how to get a pretty sharp edge, and the more accomplished of them would know enough to try to keep their stones flat and their blades (at least the last few millimeters of the blade) relatively flat and with uniform scratches. Efficiency would demand this much of their attention at least.

Two cents.

Stan

Yeah, it's certainly easier to maintain a sharp edge if the face and your stones have complementary shapes, and "locally flat" (the last couple mm as you say) is probably the most practical/efficient way to get there. That's what I do FWIW.

I think it's important to recognize that in that case flatness is a means (to efficient maintenance) rather than an end, though.

[Patrick Chase]

If a cap iron (a.k.a. chip breaker) was involved, did anything other than a flat back prevent the shavings constantly clogging between the cap iron and the blade?

Sure - any complementary shapes work. All that matters is that they mate.

Practically speaking I think that crosswise (parallel to the blade) flatness near the tip is by far the easiest way to get there, but I'm sure somebody out there has devised a way to grind non-flat complementary shapes...

[Patrick Chase]

Hi David

No figures have been published by Spyderco, consequently we can only estimate this.

The Medium is around 2000-3000. The Fine and Ultra Fine are reputed to be the same, but that the UF is flatter. That does not make sense to me. I would estimate the UF around 6000-8000, and then it seems logical that the Fine is between the two (i.e. 4000-5000).

Honing with green compound takes it to 30000. That is a big jump, and quite noticeable in terms of the greater ease with which a blade will cut Jarrah end grain.

Regards from Perth

Derek

Our of curiosity, whose green compound?

The reason I ask is because most of that stuff (LV's included) is an Al-Oxide + Cr-Oxide blend, with the Al-oxide being quite a bit more coarse. The average particle size may be 0.5 um and therefore ~30 kgrit as you say, but there are typically a bunch of larger particles in there. The scratch pattern is therefore rather more coarse than you'd get on, say, a tightly graded 0.5 um lapping film. This is easily seen under 'scope.

Of course we're well into overkill here anyway, so I don't question your bottom-line results...

[Patrick Chase]

Here's a question or three: if you come to the conclusion that cabinetmaker's of yesteryear honed the bevel alone and "sort of" removed the wire, without any effort to work the back of the blades .... would you change your current sharpening regimes and do the same?

In the same vein, knowing that oilstones probably do not go above the equivalent of a Japanese waterstone rated 6000 grit, would you stop honing above this level (whatever you use)?

Perhaps you are reluctant to change what you do. Is this because you do so out of habit, or because you believe that a modern day sharpening regime is superior to one from yesteryear?

Regards from Perth

Derek

Answering honestly: For me at least woodworking isn't an entirely rational pursuit, so my answers would be "no", "no", and "habit".

Just because you know it's OCD doesn't mean you can resist the compulsion.

Seriously, I think there's some benefit up to 10000# or so, and maybe a bit more depending on the wood and the application. Beyond that you're splitting hairs, whether literally or figuratively (sorry, couldn't resist an "HHT" joke).

I've used the Spyderco ultra-fines for decades for ski tuning and more recently for woodworking, and there's no way you're going to convince me that's equivalent to a 6000# stone. Maybe 3K based on careful examination of scratch patterns (you can't judge anything from the "feel" of the stone IMO).

[Jeffrey Martel]

My question is: Does it matter what they used to do? Aside from someone attempting to be 100% period correct, why would you want to do it exactly as it was done a few centuries ago? I would think that the best course of action is to compare flattening the back vs not flattening, and see which works best. Use whichever method works best. Personally, I don't care about historical accuracy. I care about what works best for my application.

[Allan Speers]

Here's a question or three: if you come to the conclusion that cabinetmaker's of yesteryear honed the bevel alone and "sort of" removed the wire, without any effort to work the back of the blades .... would you change your current sharpening regimes and do the same?

In the same vein, knowing that oilstones probably do not go above the equivalent of a Japanese waterstone rated 6000 grit, would you stop honing above this level (whatever you use)?

Perhaps you are reluctant to change what you do. Is this because you do so out of habit, or because you believe that a modern day sharpening regime is superior to one from yesteryear?

Regards from Perth

Derek

That cuts right to the heart of the matter, don't it?


One could also ask a similar thing in a different way:

Given today's superior tools and compounds, and assuming you're a hobbyist who has no need to work as fast as humanly possible, is there any good reason NOT to flatten a back, or to use a strop?

I sure can't think of one.

[Kees Heiden]

Flattening isn't really a pleasure.

[Derek Cohen]

Flattening isn't really a pleasure.

Especially with oilstones.

Which is likely a reason why many vintage blades are not flat. The trouble is, one does not know if the vintage blades we find in this condition come from a professional or an amateur. It makes it difficult to conclude anything.

Modern blades are pretty flat, and modern abrasives are quicker working and offer higher grits. Progress?

Regards from Perth

Derek