Just wondering if there is a specific relationship between the blade projection and the throat opening. Such as, the blade projects 1/64″ therefore the throat opening should be “X”. I’m beginning to use the one decent plane I could afford, a No. 5, to accomplish both flattening and smoothing and would like to reset more quickly than trial and error.
Thanks for any help
Keith
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Replies
I use hand planes a lot. I had heard that you want the throat to be twice as far out as the shaving you are going to take. Truthfully, I don't pay much attention to it. For the hand plane where I want fine shavings, I try and get the throat narrow but I've never measured it. If I had to guess, the gap is on the order of a 32nd or a 64th away from the blade. If you had a block plane with an adjustable throat you could experiment and get a feeling for it. The tight throat is to minimize tear out. If you aren't having tear out, it's less important. Hope this helps.
Absolutely it helps!
Thanks for the insight!
It's no doubt possible to use the geometry of the plane parts to work out a formula for how much to move which adjuster to get a certain mouth gap for a certain blade projection. My own math mentals are not up to that just now, though. :-)
But, as Joel intimates, there's probably more likelihood of success via trial and error - although you could make a chart up of your commonly found & used successful gap & projection values, using machinists tools such as a vernier and feeler gauges to make the measurements of your successful settings.
As Joel mentions, the close-mouth approach is to get the plane sole in front of the blade to aid in the prevention of tear-out - the lifting of fibres torn from the wood just in front of the cut shaving. In practice, there are other factors that can reduce tear out: a very finely-set chip-breaker; a steep cutting angle for the blade. Use of these can reduce the need for a tight mouth in reducing or preventing tear-out.
The best anti-tear-out plane I have is a Blum plane:
https://blumtool.com/
This has a unique design of "cap-iron" or chip-breaker that is very effective indeed at preventing tear out, basically by bending the cut shaving very tightly, very early in the cut so that it it breaks the fibres rather than tearing them out.
Any plane with a chip-breaker can have it very finely set .... if the parts are well-made and maintained; and the user can develop the technique of setting a very small blade projection. Here's a useful FWW article on the topic:
https://www.finewoodworking.com/project-guides/handplanes/the-physics-of-handplaning
With bevel up planes sporting a very thick blade but no chip-breaker, the best approach is probably a tight mouth and a steep cutting angle, where tear out is a possible issue.
If the wood is nice, though - the grain running upwards rather than downwards ahead of the blade, with no roiling grain, knot-swirls and so forth, there's no real need to prevent tear out as its very unlikely unless the blade is seriously blunt.
I gotta quit clicking on links... :drool:
I agree those were some nice hand planes.
Pendulums swing too far and "mouth size doesn't matter" I believe is an example of that. Close it up pretty tight. I think the best, tear out free performance comes from a very tight mouth opening and cap iron setting not quite as close as many recommend. You'll have to experiment for thirty minutes or so and then you'll have it. Whatever you do, don't follow some silly "prescription" that mentions measurements you can't actually make in a shop environment. Leave a little art in the process, please. If you can't resist 1/128th of an inch, you should set up a home machine shop and forget woodworking. It's going to drive you nuts.
Mouth size depends on the angle of the bed or the cutting angle, and how much is needed for clearing shavings.
The mouth size does not matter when the cutting angle reaches 55 degrees. You can have it as wide as you like.
When a chipbreaker is closed down, it also closes up the throat, and so the mouth needs to be opened wide enough to clear shavings. A plane with a closed chipbreaker, as will one with a high cutting angle, is unaffected by the mouth being opened wider.
A tight mouth is used for taking fine shavings, which automatically result in better tearout control. many imagine that it is the tight mouth that controls tearout. It likely does so, but fine shavings do as well.
Regards from Perth
Derek
One thing to note is that if the mouth is too narrow, the chips can have a hard time getting thru and that can create chatter. I have accidentally closed down my mouth too much and found that to happen until I opened it up. I'm using a collection of vintage Stanley Bedrocks (to let you know what my bed angles are, as that can make a difference as well.)
I also found that the mouth opening doesn't matter much unless your sole is flat right in front of the mouth. That area is prone to wear faster than other parts of the sole because of the upward pressure of the chips being created. Check that that area is not worn.
Thanks to everyone. Outstanding information, and great to have many different perspectives. Very helpful all
I dont know squat about planes. But if you like youtube Rob Cosman covers them very very often and it seems like good information on all aspects.
Here is how tear out is mitigated with a hand plane:
Sharpen up
Take a lighter cut
Change planing direction
Close the mouth
Move the chipbreaker closer
Any one or a combination of these may work. Read that sentence again. This information is many decades old and there is nothing new to be 'discovered.'
Get a piece of gnarly wood and spend an hour figuring out what works for the planes you have. THEN MOVE ON TO THE NEXT SKILL YOU NEED TO MASTER.
Ys but no but yes but .....
How sharp?
How light a cut?
What directions to change the cut with reference to the grain?
Close the mouth to how close?
Move the chip breaker how close the the edge?
Just kiddin', Charles. As you intimate, experimentation will discover the refined answers. :-)
On the other hand, a theoretical understanding of the above factors (and the blade cutting angle) is likely make the experiments go faster and with more direction towards th0se answers rather than down various rabbit 'oles.
Why else would we all come here, or read FWW, to discover both experience and theoretical advice?
Don't forget, though, that theoretical advice, if somewhat confused, inchoate or plain ideological, can also serve as a means to avoid those warrens. I has a list of webWWorkers I tend to regard with a raised eyebrow and even a curled lip!
Enjoy your woodworking!
I have some planes with adjustable throats. It's a good way to get a feel for how the throat opening and the blade projection work together. The only downside is that you have to be careful that everything is perfectly flat -- the sole and the movable part -- or you can get bad scratches as you plane.
Anybody who thinks mouth aperture doesn't matter can prove to themselves that it does by setting depth on an adjustable mouth block plane with the mouth wide open, then progressively close the mouth down and watch the shaving change (while not changing the depth setting at all) while planing a board that is producing tear out. At a very close setting, the chip will come out of the mouth straight with no curl -- Nirvana according to the wonks, but the surface will in fact start to clear with all or almost all tear out eliminated.
A block plane of course has no chip breaker. You can watch for yourself as the surface clears as you do nothing more than close the mouth.
This same exercise can be performed with an ECE Primus smoother with the cap iron set back 1/8" or more -- totally out of play, then just adjust the mouth on the Primus and watch the chip change and more importantly surface quality change.
Again, none of this is new. I am not imparting, nor claiming to impart, new information. The frog on your plane adjusts for a reason. The Primus has a mouth that adjusts for a reason. Your block plane has an adjustable mouth for a reason. Use all weapons at your disposal.
Ooo-er! You're in danger of starting another long-winded conversation concerning plane maintenance, refinement, set-up and how often they should be polished with what. :-)
For example - how often do we plane users do a wobble whilst planing vigorous-like, causing a momentary plane-tip, especially on a narrow piece, resulting in the sharp corner of the plane atween sole and side cutting a line on the workpiece? I have done it during those long and tiring sessions, especially with a heavier plane (but never with a wooden-bodied plane).
S0 .... should we relieve those corners between sole and side to avoid putting a cut-line on the workpiece when we do have a wobble or cant? If so, how much relief?
And what about the procedure for matching the knob and handle shapes to the individual user's hands and stance? Must we make eight knobs and handles to get to the right ones "by experience". Surely FWW has an article somewhere about this matter.
Or perhaps others have a secret formula for deriving the plane handle dimensions, lean, bulk and even the dodu? :-)
I keep it simple
Jack Planes - Sharp cambered iron, generous mouth opening, cap iron backed up a bit, heavier cuts
Jointer Planes - Sharp Iron with less camber, cap iron closer to cutting edge, smaller mouth opening, lighter cuts
Smoothers - Sharp iron with minimal camber or flat with relieved corners, cap iron close to cutting edge, mouth closed up a fair bit, lightest cuts.
Bevel Up Planes - I monkey around with the mouth opening, grind angle, and depth of cut to suit what I'm doing. Tweak until it works.