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13th June 2005, 03:26 AM #1
Planing end grain - a little experiment
I had a little free time today and decided that I would take a few pictures of my efforts at end grain planning to demonstrate that the mouth size of a block plane has no effect on the result. Just for the disbelieving (since a small mouth is stated by many here as a necessity for preventing tearout).
Firstly, in my experience (limited by my amateur status), end grain does not tear out if the blade is sharp enough. I do get tearout on some timber, notably awful stuff such as construction-grade Radiata Pine (no one should attempt end grain planning with this timber – it is heart breaking!), but this does reduce (never completely) with a really sharp blade.
Secondly, a lower cutting angle requires less effort but even a high angle plane will cut end grain. For example, I have successfully used a HNT Gordon Try Plane (60 degree cutting angle) on a shooting board. On the other hand, a low angle jack plane will do the same job with less effort, and produce a smoother cut.
When it comes to small block planes, I’d rather use a low angle (such as my Stanley #65) than a high angle (such as a Stanley #18). But the question is often raised whether one would choose from a block plane such as a LN #102 (which is a low angle plane but has a wide mouth) or a LA block plane with an adjustable mouth. I would say that one should get the adjustable mouth, but because it is useful for planing interlinked face grain rather than as a specialized plane for end grain.
So as a test I chose two pieces of timber, one Scandinavian pine and the other American Cherry. The plane used was my Stanley #65 block plane, which has a low cutting angle and an adjustable mouth. It is well tuned and uses a Hock blade. The blade was sharp but not especially sharpened for the experiment. Photos were taken of the results: both timbers with the mouth closed down and with the mouth as wide open as possible.
The results were clear. I could not tell the difference in performance when the mouth was open or closed.
I tell you what – here are the pictures and YOU say which was which!
About the pictures: those with the cherry came out better than those with the pine. My apologies, but I did not get a chance to examine them until later. Still, they should do the job.
The first two sets of pics are Cherry, the third set is Pine.
Regards from Perth
Derek
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13th June 2005, 09:57 AM #2
Your spot on alright derek.........I have shooting planes setup made up out of old 4 and 1/2's .......I stuffed up with one of them when I skewed its frog....and opened the mouth poorly,,,,too big and uneven, I supposed I should have tried harder and got it right but the fact that mouth size doesn't matter made me a bit complacent I surpose......
But It didn't affect their performance.......
I went to town describing these shooting boards in that 'ramped shooting board' thread of yours if interested........
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13th June 2005, 01:10 PM #3
Very interesting point you raise Mr Cohen. Whilst end grain will never tear out the same as long grain does. I still would've thought a closed mouth was needed.
Myth Busted.
How closed/open did you have the mouth for this little speriment?Boring signature time again!
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13th June 2005, 03:32 PM #4Originally Posted by outback
Derek's observation makes sense, as cutting across the grain slices the fibres and, since they are at 90 deg to the edge, there is little tendency for the blade to porpoise through the wood, causing tear out.
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13th June 2005, 03:42 PM #5
Outback asked
How closed/open did you have the mouth for this little speriment?
The "open mouth" state was as wide as the mouth could be opened, from memory about 10mm.
Regards from Perth
Derek
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13th June 2005, 06:53 PM #6
Thanks Derek, we're certainly talking a heap big enough difference for any changes to show up.
All food for thought isn't it.Boring signature time again!
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14th June 2005, 10:17 AM #7Intermediate Member
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I'm sure all you experienced people know about this but it was a revelation to me:
I was planing the end grain on a large piece of unnamed eucalyptus the other day. The first couple of slices were pretty rough. Then I got through into the "unseasoned" (read wet) timber and the plane sliced through so beautifully I couldn't believe it.
Does this always hold true?
Mike
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14th June 2005, 11:03 AM #8
I agree, I wouldn't have thought mouth size would have made much difference to tear out in end grain. Wouldn't it be more down to the sharpness of the blade?
When you're planing end grain, the fibres are on end. As the blade begins to cut, it pushes the fibres in the direction of planing and they bend. If the blade is blunt, then more resistance is present and the fibres bend more, then they are finally cut and spring back once the blade has passed, or are snapped off leaving a hole. That's why you get a rough surface or actual tearout.
I'd guess that the low angle plane tends to cause less flexing of the fibres given the same sharpness of blade but I have no evidence for that. In any case, I can't see how the mouth opening would have any affect on this at all. You can get very smooth results paring with a sharp chisel and it has a mouth opening of infinity.
When planing long grain, the mouth opening controls the size of the chip and that is an entirely different set of physics to what is going on with end grain planing, don't you think?"I don't practice what I preach because I'm not the kind of person I'm preaching to."
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14th June 2005, 11:24 AM #9
When I open my mouth too wide the Boss usually tears me out a new a..hole.
Yes folks, I'm baaaaaakk!
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14th June 2005, 11:26 AM #10
When I stop and think about it, which I rarely if ever do.
Yes, Yes and Yes.Boring signature time again!
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14th June 2005, 12:16 PM #11Originally Posted by pelorus32Cheers,
Adam
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I can cure you of your Sinistrophobia
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14th June 2005, 11:06 PM #12
Hi Derek -
It's all about the failure modes of the wood - chip types and all that....
Tear-out occurs with type I wood failure - and closing the mouth (and taking a finer cut) are treating the symptoms of the problem - but are not the cure...
What you're after - is getting the wood to fail right at the blade edge (type II failure), and that's really a function of blade angle.
When sharpening a blade - you strive to have to lowest possible blade angle consistent with type II chip formation. Of course, wood isn't a homogeneous material - so it still helps to close the mouth and take a finer cut - even if you've selected the correct blade angle for the wood you're working...
For end grain - you're after the lowest possible blade angle - so that the horizontal severing component of the applied force is maximized - (the other component is the lifting component). With end grain - you'll see two effects - the grain being pushed sideways by a dull blade, or the wood fibres fracturing below the surface if the angle is too high (they get lifted)... A clean cut in end grain has a "wet" look...
Skewing a blade (or the body of a regular plane in use) has the effect of lowering the effective cut angle - the wood "sees" a lower cut angle - and the cut is cleaner.
Now if you really want to experiment - why is a chip-breaker necessary, if the wood fails at the blade edge?
Cheers -
Rob
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15th June 2005, 09:49 AM #13Originally Posted by Rob Lee
'Cos it ain't a bleedin' "chip-breaker", but a cap-iron! If your cap iron is contacting the chip during the "breaking" phase, you've got it set a bit fine!
You need to pre-tension thin cutting-irons on a standard Bailey frog if you don't want it chattering to you all day. This is a sum of the effect of the thin cutter and the fact that the bed usually ceases supporting the blade somewhere above the back of the bevel (depends on the individual frog design, in which there is some minor variation over time)
Having thicker cutting irons reduces the need for a cap iron, but the damping effect of pre-tensioning is still beneficial up to a point. And I'd like to have the time and equipment to do the experiments to show at what point thicker blades become counter-productive, as the support bed gets further from the cutting edge with the thicker blades (assuming the same grinding angle). I suspect Rob's mob have done this, since he's on record as saying that blades over an 1/8" have no extra benefits, and my own experience points to this as about the convergence point, alright.
So the trend to bevel-up planes has all sorts of things going for it, such as a simplified mechanism, the potential to have the blade supported almost right at the cutting edge, not to mention the ease of altering cutting angles....
Do I get the jellybean, Mr Lee??
Cheers,IW
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15th June 2005, 10:22 AM #14Originally Posted by Rob Lee
Originally Posted by Rob Lee
And for skewing I think thats limited as well......not only (in my opinion) does the effective pitch drop but also the clearence angle , you know the angle between wood and blade......which is significant in end grain , I would think, because of springback.......so there must be a point where you can skew too much or else the fibres will push up on your blade after cut causing another kind of chatter I'd imagine........so the ideal bevel and setting in plane must be within a small range.......
So, in my opinion, the most ideal shooting plane is a bevel up, slightly skewed plane with a thick blade.........but in practise I don't think it would improve your work.....other things like planing style, sharpening skills, choice of tools for wood type etc would carry far more significance to your chances of success........I mean a regular stanley on its side with a thick sharp blade works 90% of the time........
very interesting stuff.......
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15th June 2005, 11:12 AM #15SENIOR MEMBER
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Originally Posted by apricotripperDan
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