bugbear
Established Member
Corneel":2c5kmj5u said:
That's interesting; do you think that (yet another) intermediate cambered plane between the scrub plane and fore plane would have reduced the total work of planing?
BugBear
scrub planes and camber - how does it work?
- Thread starter Jacob
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That's interesting; do you think that (yet another) intermediate cambered plane between the scrub plane and fore plane would have reduced the total work of planing?
BugBear
Bluekingfisher
Established Member
Cheshirechappie":2vloe32q said:
I was reading almost exactly the same quote only last night from the opening chapter of Ch12, Buying and choosing hand planes and scrapers' 8)
Corneel
Established Member
bugbear":2pf14lsx said:
No idea really. Just that the scrub is highly effective. I used it strictly crossgrain. The foreplane was from crossgrain to more and more diagonal to long grain, as the situation dictated.
But I did some trials first to see if I could get the same effect with the foreplane as the scrub, but it wasn't nearly as effective. The planes are now in storage (workshop gets moved), so I can't meassure the radius of the camber. The scrub has the typical narrow radius of the german scrub planes. The fore is more like a jack plane with 8" radius or so.
jimi43
Established Member
I think for penultimate finishing the solution is the toothing plane....one like Stewie's recent masterpiece would be nice....
After that you can use scrapers and/or abrasives. I see Abranet/Micro-Mesh as a perfectly suitable ending to a good finish... if the wood is tricky...but recent tests with "THE LUMP" would lead me to try the infill mitre.
Since craftsmen of old did not have the benefits of modern abrasives....in particular the fine mesh stuff...I guess the wouldn't pay the sort of money an infill mitre would cost if it wasn't the ultimate solution. Piano makers...etc.
Jimi
After that you can use scrapers and/or abrasives. I see Abranet/Micro-Mesh as a perfectly suitable ending to a good finish... if the wood is tricky...but recent tests with "THE LUMP" would lead me to try the infill mitre.
Since craftsmen of old did not have the benefits of modern abrasives....in particular the fine mesh stuff...I guess the wouldn't pay the sort of money an infill mitre would cost if it wasn't the ultimate solution. Piano makers...etc.
Jimi
Cheshirechappie
Established Member
Things that make planing easier (less energy for a given amount of stock removed, but paying no attention to finish):
1) Smaller, lighter planes - less mass to stop and start.
2) Narrower irons.
3) Wider mouths.
4) Lower effective pitch.
5) Single irons - no cap iron, or cap iron set back.
6) Planing cross-grain.
Pretty much the definition of a scrub plane.
Where better finish is desired, especially on more interlocked or wild-grained timbers, the virtual opposite of all the above (except perhaps plane size and iron width) is needed, with consequent increase in effort for quantity of stock removed.
On camber, and going back to my first post in this thread, I'll stick my neck out and suggest that energy expended is more likely to be proportional to cross-sectional area of cut than it is to length of cutting edge. A wider, shallower-cambered iron will remove as much stock as a narrower, quicker-cambered iron for the same input of energy, if the c/s area of the cut they make is the same.
In practice, it's more complicated because the cutting iron rarely makes a full c/s area cut all the time; there's plenty to do removing the 'waves' left between the initial deep troughs, so 'partial-effort' cuts to trim up the surface occupy a fair proportion of the work done. Also, as previously postulated (sorry about the big words - just ignore them if you can't be doing with them!) wider-ironed planes tend to be bigger and heavier (and thus need more energy to move) than narrower-ironed planes.
To really test the hypothesis, you'd need two otherwise identical planes, one fitted with a narrow, deep iron, and one with a wide, shallow iron, both giving the same c/s area of cut. That doesn't really happen in the real workshop, so the whole thing is a bit academic anyway! Probably best stick to what we know works from several centuries of experience.
1) Smaller, lighter planes - less mass to stop and start.
2) Narrower irons.
3) Wider mouths.
4) Lower effective pitch.
5) Single irons - no cap iron, or cap iron set back.
6) Planing cross-grain.
Pretty much the definition of a scrub plane.
Where better finish is desired, especially on more interlocked or wild-grained timbers, the virtual opposite of all the above (except perhaps plane size and iron width) is needed, with consequent increase in effort for quantity of stock removed.
On camber, and going back to my first post in this thread, I'll stick my neck out and suggest that energy expended is more likely to be proportional to cross-sectional area of cut than it is to length of cutting edge. A wider, shallower-cambered iron will remove as much stock as a narrower, quicker-cambered iron for the same input of energy, if the c/s area of the cut they make is the same.
In practice, it's more complicated because the cutting iron rarely makes a full c/s area cut all the time; there's plenty to do removing the 'waves' left between the initial deep troughs, so 'partial-effort' cuts to trim up the surface occupy a fair proportion of the work done. Also, as previously postulated (sorry about the big words - just ignore them if you can't be doing with them!) wider-ironed planes tend to be bigger and heavier (and thus need more energy to move) than narrower-ironed planes.
To really test the hypothesis, you'd need two otherwise identical planes, one fitted with a narrow, deep iron, and one with a wide, shallow iron, both giving the same c/s area of cut. That doesn't really happen in the real workshop, so the whole thing is a bit academic anyway! Probably best stick to what we know works from several centuries of experience.
Jacob
What goes around comes around.
Actually it is, by virtue of simple geometry, and it is greatest when the edge (of a given length) is a semi circleCheshirechappie":2kjogtx7 said:
Unfortunately it won't. That's the whole point of using a scrub plane, otherwise why bother with the rough finish if you can do it just as easily with a shallower camber?
Not academic at all nor a hypothesis;, we know it works otherwise there would be no point in a scrub plane at all.
Actually I have got planes much as you describe (3 single iron scrubbers) and there is no doubt that narrow and deep removes more faster than the others.
The question you would have to answer is why use a scrub plane if there is no advantage over a shallower cambered plane, considering the rough surface produced?
I can see what the dilemma is - if you google away everybody accepts that the whole point of a scrub is rapid removal (to which I'd add deep removal) of waste, but accounts of the reason for cambering seem to skate over this. In fact it is one and the same - the whole point of camber is to remove more material and/or with less effort.
bugbear
Established Member
Jacob":hwqxm4lh said:
Ooh, that's not true; camber is dead handy, and has more strings to its bow than that.
Camber allows you to joint an edge square, and camber allows adjacent smoothing passes to join up without a step.
BugBear
Cheshirechappie
Established Member
I think I'll stick with what I've already said.
We know what works in practice. A small, nimble, narrow-ironed wide-mouthed scrub takes stock off fast, but so does a woody jack with a wider iron and wide mouth. Unless somebody presents some carefully conducted test results comparing energy expended using both, it's all opinion, anyway.
We know what works in practice. A small, nimble, narrow-ironed wide-mouthed scrub takes stock off fast, but so does a woody jack with a wider iron and wide mouth. Unless somebody presents some carefully conducted test results comparing energy expended using both, it's all opinion, anyway.
Camber/curve certainly works. Try removing the same amount of material with a straight, but same width cutter. The point of entry at the end of the curve is very small and then widens out to the edges corresponding with the curve. Smaller radius, smaller point of entry, the cutter is effectively narrowed as well unless the depth setting makes it cut all the way to each side which would require a lot of force in most woods. When I've taken the time to notice the depth setting I use uses probably 2/3rds to 3/4ths of the width of the scrub's cutter.
Any plane with a sharper curve to its cutter can accept a deeper iron setting and therefore remove wood faster than an identical plane with a cutter that has much less curve.
I've come to understand that scrubbing should be close to effortless. If it's not your depth setting is too deep and/or the cutter not curved enough or perhaps thick enough (part of the reason No. 4's make lousy scrubs when compared to the real thing).
Any plane with a sharper curve to its cutter can accept a deeper iron setting and therefore remove wood faster than an identical plane with a cutter that has much less curve.
I've come to understand that scrubbing should be close to effortless. If it's not your depth setting is too deep and/or the cutter not curved enough or perhaps thick enough (part of the reason No. 4's make lousy scrubs when compared to the real thing).
jimi43
Established Member
There is an element of skew with the edges either side of the leading edge too...which will aid cutting.
Jimi
Jimi
Jacob
What goes around comes around.
No it doesn't. Not as fast.The scrub does it faster. That's the whole point, otherwise why botherCheshirechappie":4w38wfzn said:
It's not opinion it's a simple fact; everybody says a scrub is for fast removal - everybody who uses one agrees. Thats what a scrub plane is for. If it didn't do what it says on the tin there wouldn't be any point in using it.
Jacob
What goes around comes around.
Yes - not quite effortless but surprisingly easy.CStanford":213j8noj said:
Cheshirechappie
Established Member
I feel that this is degenerating into an argument for the sake of having an argument.
Scrub planes work well at removing a lot of stock very fast. Jacob's contention is that a narrow, aggressively cambered iron will remove stock with less effort than a wider, less aggressively cambered iron. Earlier in the thread, I ventured to suggest that other factors may be relevant, such as the fact that scrub planes tend to be smaller and lighter than (say) jack planes, and thus need less effort to heft. There is also no evidence (other than opinion) offered to support the hypothesis. Also earlier in the thread, I offered another hypothesis, based on scientific work done on metal-cutting machine tools, that the effort required to remove stock may be proportional to the cross-sectional area of the cut, and not necessarily the length of cutting edge. As I said at the time, since the science I mentioned pertains to metals, I'm not sure how well it might apply to wood, with it's grained rather than homogenous structure. Consequently, I certainly don't advance it as indisputable fact, just a possible explanation.
We have no factual data to support any of the hypotheses advanced. Until someone supplies the results of some replicable experiments measuring the energy consumption of otherwise identical planes fitted with aggressively cambered and shallow cambered irons doing identical work, perhaps making the same cross-sectional area of cut, we're debating opinion, not established fact.
Until then, I'm content to stick to knowledge based on centuries of experience. Fast, deep stock removal - scrub plane used cross-grain. Aggressive, not-so-deep stock removal to level up sawn timber - jack plane, used cross-grain. Finer work, finer planes, used long-grain.
Jacob - I recognise your right to advance your ideas and to discuss them with whoever wishes to participate, but I feel that I have made all the useful contribution I can, and have no further wish to argue for the sake of it.
Scrub planes work well at removing a lot of stock very fast. Jacob's contention is that a narrow, aggressively cambered iron will remove stock with less effort than a wider, less aggressively cambered iron. Earlier in the thread, I ventured to suggest that other factors may be relevant, such as the fact that scrub planes tend to be smaller and lighter than (say) jack planes, and thus need less effort to heft. There is also no evidence (other than opinion) offered to support the hypothesis. Also earlier in the thread, I offered another hypothesis, based on scientific work done on metal-cutting machine tools, that the effort required to remove stock may be proportional to the cross-sectional area of the cut, and not necessarily the length of cutting edge. As I said at the time, since the science I mentioned pertains to metals, I'm not sure how well it might apply to wood, with it's grained rather than homogenous structure. Consequently, I certainly don't advance it as indisputable fact, just a possible explanation.
We have no factual data to support any of the hypotheses advanced. Until someone supplies the results of some replicable experiments measuring the energy consumption of otherwise identical planes fitted with aggressively cambered and shallow cambered irons doing identical work, perhaps making the same cross-sectional area of cut, we're debating opinion, not established fact.
Until then, I'm content to stick to knowledge based on centuries of experience. Fast, deep stock removal - scrub plane used cross-grain. Aggressive, not-so-deep stock removal to level up sawn timber - jack plane, used cross-grain. Finer work, finer planes, used long-grain.
Jacob - I recognise your right to advance your ideas and to discuss them with whoever wishes to participate, but I feel that I have made all the useful contribution I can, and have no further wish to argue for the sake of it.
Jacob
What goes around comes around.
Thanks for that CC - it has been an interesting exchange of ideas.Cheshirechappie":3mwmic7q said:
Random Orbital Bob
Established Member
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