Image of planed Alaskan Yellow Cedar

Brian recently send me an offcut of his AYC "Kez practice beam". As you'd expect it's a near-perfect piece of wood, extremely uniform with very faint rings.

To get a quick look at the structure I planed it with a 40 deg cutting angle and took a picture with extremely harsh raking light oriented perpendicular to the grain. Each pixel in this image is 2.6 microns, and the entire image is 2.6 x 2.6 mm at the wood surface. For reference this surface appears uniform with fairly high sheen to the naked eye.

Attachment 371406


A couple notes:

• Individual fibers average about 12 pixels = 31 microns in diameter. The "book value" for AYC is 30 um per some papers I've seen, so this piece doesn't appear to be exceptional in that regard. 30 um is just over 1 mil, so when planing competitors make thinner shavings than that they're actually slicing fibers into pieces lengthwise.
• Rings average about 240 pixels = 0.6 mm in width. If you look closely you can see 5 light ring boundaries in the image. Did I mention that this is some *very* finely-ringed wood?

Very interesting! Amazing how tight the growth rings are, isn't it? Most of what I have ranges from being that tight to at max about 1/16" on a board with "huge" rings.

Here in the Pacific Northwest we get some rather widely spaced growth rings. Must be all the rain.

jtk

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Originally Posted by Patrick Chase

...If you look closely you can see 5 light ring boundaries in the image.

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What is the significance of this?

That's really, really nice.

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Originally Posted by Pat Barry

What is the significance of this?

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Probably none to you. It grew out of another thread, and specifically a discussion of what attributes might make AYC a good choice for planing competitions.

The picture shows about what I expected: Very tight rings, but fairly large/coarse fibers (typical domestic hardwoods have sub-10 micron fibers IIRC).

What I'm beginning to suspect is that it's harder to get down under a mil shaving thickness with AYC due to fiber size (I had to work at it a bit to get past that point), but that once you get through that "barrier" it has a lower floor than other woods.

I also think that the moisture-content dependence that Brian has noted is due to cell wall thickness. Once you get start cutting shavings thinner than the fiber diameter the only things giving the shaving integrity are cell wall "ribbons". If the wood is too dry those may be too thin/soft to do the job (recall that bound moisture in wood engorges the cell walls). Brian, where did people end up in the "dry Kez" again?

Among other things this means that I was off-base when I mocked the over-excited guy in a video for being proud of his 16 micron shavings. When I do that on a hardwood I'm basically shearing off entire fibers. When he did that on Cedar he was slicing fibers in ~half.

More later.

Quote:

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Originally Posted by Patrick Chase

Probably none to you. It grew out of another thread, and specifically a discussion of what attributes might make AYC a good choice for planing competitions.

The picture shows about what I expected: Very tight rings, but fairly large/coarse fibers (typical domestic hardwoods have sub-10 micron fibers IIRC).

What I'm beginning to suspect is that it's harder to get down under a mil shaving thickness with AYC due to fiber size (I had to work at it a bit to get past that point), but that once you get through that "barrier" it has a lower floor than other woods.

I also think that the moisture-content dependence that Brian has noted is due to cell wall thickness. Once you get start cutting shavings thinner than the fiber diameter the only things giving the shaving integrity are cell wall "ribbons". If the wood is too dry those may be too thin/soft to do the job (recall that bound moisture in wood engorges the cell walls). Brian, where did people end up in the "dry Kez" again?

Among other things this means that I was off-base when I mocked the over-excited guy in a video for being proud of his 16 micron shavings. When I do that on a hardwood I'm basically shearing off entire fibers. When he did that on Cedar he was slicing fibers in ~half.

More later.

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Ah, so you are saying its easier to make a superfine shaving in hardwoods because their fibers are smaller?

It looks like your shaving didn't slice any fibers in half, right?

Still not clear what the significance is in seeing 5 light ring boundaries or even where you are seeing them or why you do or don't want to see them.

Nice picture though, what does a more macro image look like?

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Originally Posted by Pat Barry

Ah, so you are saying its easier to make a superfine shaving in hardwoods because their fibers are smaller?

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I think that it's easier to get down under a mil in hardwoods for that reason. I suspect that AYC is easier once you're down under ~10 microns and trying to slice fibers in both, though. I haven't gotten there yet :-).

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Originally Posted by Pat Barry

It looks like your shaving didn't slice any fibers in half, right?

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For the most part, right. This was a thicker cut. For this purpose I wanted to expose the fiber structure rather than alter it.

I'll take a shot at normal magnification the next time I work with it. It's actually a somewhat boring-looking wood IMO, with no grain or figure to speak of. As I said earlier this particular cut looks dead smooth to the naked eye with moderate sheen.

Here's another shot of the same piece under the same lighting conditions, this time after taking a 0.5 mil (~13 um) shaving. The piece looks very shiny at the "macro" level, with mirror-like reflectivity at high grazing angles.

Attachment 371551

You can see that individual fibers have now been cleaved, such that the surface no longer consists of convex fiber hulls.

I used a PM-V11 iron, which is a bit higher in alloy content than you'd ideally want for this sort of thing, but it can be honed to a sufficiently fine edge on 0.25 um diamond compound.

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Originally Posted by Patrick Chase

You can see that individual fibers have now been cleaved, such that the surface no longer consists of convex fiber hulls.

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This looks more like I would expect a planed surface to look. How did you manage to get the 'hulled' look before? That was pretty interesting.

Interesting photos, could you take one of the surfaces I planed I’m curious to how they look under magnification. They were shiny but probably dulled down during transit.

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Originally Posted by Pat Barry

This looks more like I would expect a planed surface to look. How did you manage to get the 'hulled' look before? That was pretty interesting.

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You're aware that these images are both at about 10,000 pixels/inch, right? As I said in the OP, 2.6 microns/pixel.

That "hulled" surface looks very smooth to the naked eye. You would only notice something like that if you were looking through a microscope or a serious macro lens like the one I used, or if you looked closely at the sheen at high grazing angles. As to how I did it, the answer is that it was a fairly thick shaving, which tends to prevent fiber-cleaving. The edge just doesn't cut as cleanly when it's lifting that much wood.

EDIT: In addition to the high resolution, the light source here is extremely specular (unmodified flash) with a 60-0 geometry, meaning that the light is coming in from about 30 deg above horizontal perpendicular to the grain, with the camera looking straight down. The second (fill) head on my flash was disabled. That combination of specularity and geometry amplifies surface variations across the grain, which is exactly what I wanted as my purpose is to understand how this stuff behaves at the fiber level.

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Originally Posted by Brian Holcombe

Interesting photos, could you take one of the surfaces I planed I’m curious to how they look under magnification. They were shiny but probably dulled down during transit.

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I'll take a pic as soon as I have some spare cycles. My impression from looking under medium magnification is that those surfaces are obviously very cleanly planed (I would expect nothing else :-), but they're probably not quite as flat on the micro scale as when they were created due to moisture-level changes.

Ah, I probably should have shrink wrapped that piece before shipping.

AYC is a dream to work and that particular piece is quite nice. I since used it to make shoji but luckily those boards with super tight growth rings are not impossible to find. I have been storing that have a light spalting to them, they will certainly be interesting as panels.

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Originally Posted by Patrick Chase

You're aware that these images are both at about 10,000 pixels/inch, right? As I said in the OP, 2.6 microns/pixel.

That "hulled" surface looks very smooth to the naked eye. You would only notice something like that if you were looking through a microscope or a serious macro lens like the one I used, or if you looked closely at the sheen at high grazing angles. As to how I did it, the answer is that it was a fairly thick shaving, which tends to prevent fiber-cleaving. The edge just doesn't cut as cleanly when it's lifting that much wood.

EDIT: In addition to the high resolution, the light source here is extremely specular (unmodified flash) with a 60-0 geometry, meaning that the light is coming in from about 30 deg above horizontal perpendicular to the grain, with the camera looking straight down. The second (fill) head on my flash was disabled. That combination of specularity and geometry amplifies surface variations across the grain, which is exactly what I wanted as my purpose is to understand how this stuff behaves at the fiber level.

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Yes - I totally understand the concept of magnification, thank you. I suspected moisture related swelling might have accounted for the previous appearance as well, although I suppose if your shaving was pulling out fibers that would do it just as well. Pictures can be a bit misleading. You get a much better appreciation for depth in the actual part with a stereo microscope. The picture on the other hand changes quite a bit with lighting angle (as you know :) ).