Est. 1998 — 27 years of woodworking knowledge
Re: Japanese blades/planes
Lyn J. Mangiameli
>My guess, and it's only that, is that it makes it easier to tension the blade between the body and the pin, at least that's my experience with other Asian planes. Of course I wouldn't dispute any evidence that it helps stabilize and damp the back of the blade :-)
Re: Japanese blades/planes
Pam Niedermayer - Austin, TX
>Well of course, that's the only way to tension the blade against the pin; but the blade is fitted so tightly without the pin/subblade, I'm not sure it matters all that much.
Pam
Re: Japanese blades/planes
Lyn J. Mangiameli
>My intention was not to state the obvious, but to surmise that the flat, softer (at least those I've seen, even if laminated) surface of the chip breaker seats better against the pin (compared to the more brittle, hardened, but dished back of the laminated blade) and spreads the pressure more evenly across a wider area. In the traditional plane without the chip breaker there are usually two focal areas of pressure.
Re: Chip Breakers Historicaly
Steve Knight
>one of these days I will have to have a regular iron tapered and see if it is improved. it is a better design then a wedge and easier to adust but more work to make.
but then i would wat to have a regular japanese blade ground flat and compare it to a wedged one. but I don't know if I could do that to a good blade. well if I ever get rich (G)
Re: Japanese blades/planes
Pam Niedermayer - Austin, TX
>Lyn, the dai is precisely fitted to the blade; therefore the pressure is precisely evenly spread without the subblade/pin assembly. When you build a dai, most of the time is spent shaping the bed to the blade, and until it fits precisely, it's not completed.
Pam
Chip breaker/sprung plane (long)
Wiley Horne--Glendora CA
>Steve,
You've put your finger on a key point. The Japanese blade is double-curvature concave on the back side--the side that has the maker mark and the ura (hollow). As an aside, it is also a bit concave on the bedding side, which is why the bedding of the dai will be shaped slightly convex across its width.
The double-curvature on the back side, particularly along the length, has the effect of the blade being sprung in the dai--even without subblade. In fact, this is why users are always cautioned not to flatten the entire back, or even the entire lower back, of a Japanese blade, but rather only the small flat below the ura right at the blade edge. Because if much of the back is flattened, you'll flatten the spring right out of the blade, and it won't bed right in the dai.
I just went and double-checked a Funahiro, which is fitted to a single-blade dai (no cross pin), and also a Mosaku, which is fitted to the more typical blade/subblade dai with cross pin. They are each sprung with about equal tension in their dais--quite tightly. To concur with Pam, they both function well without subblades--about equally--as finishing planes. I haven't even used the Mosaku with subblade yet. Now, over time, if the dais get kinda wallowed out and lose their ability to spring the blade, then the subblade on the Mosaku would begin to have some effect in pressing the blade against the bedding. But in a reasonably fresh and correctly-working dai, I don't believe this is the principle function of the subblade. I think the principle function of the subblade is to pretension the very blade edge, to give it support in gnarly woods (as Pam brings out elsewhere). Indeed, the experts sharpen the subblade to a keen edge, and make sure that it is to within 0.5mm of the main blade edge. I have been instructed that if it's not this close, it's not going to be doing much at all. Also as a consequence, the mouth on a Japanese plane with closely-set subblade in that position has to be wide enough to permit chips to pass. This is like the case in a Bailey type plane, where you can have either a tight mouth or a closely-set chipbreaker, but not both. Most Bailey folks move the chipbreaker up and keep the tight mouth, but the Japanese experts tend to keep the closely-set chipbreaker and open up the mouth. However, the single-blade dais are made with very tight mouth (shaving aperture), very much like a Knight or C&W. They are intended to be used as strictly finishing planes, and taking the lightest of cuts.
Because of this sprung bedding which I believe is unique to Japanese planes (someone please correct me if I'm wrong on this point), I totally agree with Lyn's earlier remarks about the necessity of evaluating Japanese planes 'within group' in order to test propositions about blade thickness, etc. Also Lyn was careful to describe the vibratory response of the Japanese plane as a function of an integrated set of factors (bedding, subblade, taper, lamination, etc)--and this is correct also. In fact, the plane is so highly evolved, I really wonder if these various factors can be teased apart.
Wiley
Re: Japanese blades/planes
Lyn J. Mangiameli
>Pam, I understand how the blade is bedded to the wood, I am speaking of the stresses placed on the back of the blade by the pin. A chip breaker spreads those forces rather than having them concentrated at two small points. To what extent this is meaningful with respect to performance is certainly open to question, but it is a question that could be investigated.
I have always considered one of the advantages of wooden wedged planes is that the blade is stabilized between two damping surfaces and the pressures on the blade are more uniform. With a Japanese plane without a chipbreaker, you have a blade well supported on one side, but not on the other. Yes, the driving forces are largely against the bed, but in all but scraper planes, they are also along the long axis of the blade. But most of all, there are forces that occur from the stress of the blade being tensioned by the pin. At least theoretically, I'd like to see those forces spread over a larger area, as they are on most other planes.
I also think way too much is made of the blade being fitted to the wood body on a Japanese plane. There is nothing unique about this, most wooden planes, infill planes and even cast/ductile iron planes are are capable of being (and should be) tuned to offer a well matched fit between the bedding surface and the blade.
Re: Japanese blades/planes
Steve Knight
>your right in the fitting. I don't think that is it so much as that the blade it'self is wedged. no other parts ot hold it in place so it has solid contact with the plane it'self.
Wiley deals with this better
Lyn J. Mangiameli
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Re: Chip breaker/sprung plane (long)
Steve Knight
>The front hollow (side that is down) man that is backwards (G) is hollow because that is the only way the blacksmith can make it. You should see when they try to make it flat.
The same with the back hollow without it the blade tends to warp or hump out on the front.
This is the battle I have had with my Japanese irons for western style planes. They end up with a hump on the front of the blade that I have to send out to have surface ground. Plus they usually have a little twist in them.
So part of that shape is because that's the way they need to be made to be able to be made to fit right. I don�t think it would really matter if the front was hollow or if it was flat. It�s the taper that does the wedging. It would be harder to fit to the body if it were flat. Harder to carve out a perfect flat surface then make one fitted to that blade.
Hey Eric, have we generated enough debate yet?
Lyn J. Mangiameli
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Re: Japanese blades/planes
Pam Niedermayer - Austin, TX
>OK, I see, sorry for the misunderstanding. The subblade does spread pressure, but I'm not sure how much or whether it's needed all that often.
I think you're making way too little of the difference between the beddings. Yes, other planes have well matched fittings between bedding surface and the blade; but to my knowledge, the blade is flat, perhaps except for a protrusion here and there that is accommodated by hollows in the bed. I submit that flat things slide past each other much easier that a tight curved fitting. The protrusion in the bed acts to hold the blade in place on the Japanese plane. And, I further submit, that the hollows in the bed in western planes are significant voids that make the mating even less sure.
Pam
Re: Chip breaker/sprung plane (long)
Pam Niedermayer - Austin, TX
>I've been wondering about how much structural support the pin itself provides, even without a subblade. No propositions about it now, but it's an interesting question imnsho.
I also agree about how problematic it would be to test an individual aspect. "Very highly evolved". What a great description.
Pam
Re: Japanese blades/planes
joel
>Traditional wedged western planes have wedged irons. That is what keeps the blade from slipping. (thick side down). Also for the plane to work and be set properly the wedge, the grooves for the wedge, and the iron must mate perfectly. THen of course the bedding must be right.
Re: Japanese blades/planes
Pam Niedermayer - Austin, TX
>Sure, no question, and I've used some wonderful western wooden planes.
Pam
It's a start
Eric Hedberg
>Lyn, I feel like the guy who throws the punch at a bar and then sits down to watch the fight (is there such a thing as bare knuckles inquiry?). Yeah I'd say it's a pretty good debate and as a bonus I learned a lot about Japanese planes. Now that I know the hot buttons I can plan my next "innocent question" heh, heh. Happy Birthday hand tools forum!
Re: It's a start
todd stock
>Seems like we went through this 'Foreign Tool Chic' phase before...maybe the early '80s, if old Garrett Wade/Woodcraft catalogs and my memory can be trusted. At the time, most of the pro and con discussions would quickly devolve into what were essentially faith-based arguments.
It's refreshing to see at least an attempt at a rational examination of performance issues, versus more theology.
That said, exactly how many times do we actually maintain the freshly planed surface intact for our tactile pleasure - versus scraping, sanding, filling, sanding, first coat, sanding, etc..?
Re: The next step (for me)
Lyn J. Mangiameli
>There comes a point where speculation and anecdote begins to exceed factual understanding base on objective data. For me, that point has arrived (some might argue,has been exceeded)relative to my knowledge and experience. Frankly, I rather like reaching these points, as it helps to define new areas for research.
Highly evolved or not, synergistic package or not, even "ultimate" design or not, there is much to be learned by selectively varying the "variables" (blade taper, chip breaker, angle, bedding, etc.) of the Japanese plane to determine to what extent these individual characteristics might be changed to achieve the optimal configuration (or lo, maybe even improvement), and to perhaps provide insight into how other styles of planes might be improved. I have no doubt that such variations (both deliberate and secondary to necessity) took place in the evolution of the Japanese plane, but were not recorded ("trade" secrets)except by their embodiment in the plane, and likely were not organized as they occured.
I hope such investigations are performed, though having just spent over three years conducting two of my own with several other styles of planes, I will not likely step up to the plate on this one.
Re: Japanese blades/planes
Lyn J. Mangiameli
>Pam said: "I submit that flat things slide past each other much easier that a tight curved fitting. The protrusion in the bed acts to hold the blade in place on the Japanese plane. And, I further submit, that the hollows in the bed in western planes are significant voids that make the mating even less sure."
I think these are excellent points for investigation. Probably someone with a better grasp of physics or mechanical engineering than I can identify how pressure (via lever cap, cap iron, wedge, etc) vs contact (bedding) area influence all of this and might be measured/calculated for the various planes. Some planes clearly have more contact area between blade and bed than others, and some planes have greater mating pressure placed on that interface than others. As you not, some have other forms of interferance (and I would even include some adjusters in this). One must also consider how all of this is relative to the differing forces placed on the blade/bed interface as a result of cutting edge width, wood density, edge sharpness and effective cutting angle. For example, a low bedding angle results in forces directed more along the longitudinal axis of the blade/bed interface, while a high bedding angle will direct more of that force into the bedding surface and improve mating.It is easy to see why our knowledge of such a simple tool as a hand plane is still so lacking.
All of this would be rather meaningless, except that so many of us are thrilled by the surface left by a well performing hand plane, and also so often dissapointed with the regularity with which we are unable to achieve the best of hand planed surfaces. Thus users look for better planes, and plane makers look for those little ways in which to improve the performance of their plane.
Yes, indeed.
Pam Niedermayer - Austin, TX
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Re: I agree
Todd Hughes
>If chip breakers were used to stiffen blades how do you explain thier use originaly on thick stiff blades that don't need to be stiffened.Don't forget historicaly chip breakers were not invented by Stanley but came out over a 100 years befor on wood planes with thick blades that were used, and demanded, by people that did more then just trim work with pine 2X4s . Also if the chip breaker,[funny no one ever called them "stiffners"] is just there to stiffen the blade why go to the trouble of making the chip breaker so that it is rounded on the end and slightly raised.Wouldn't just an easier to make flat piece of iron bolted to the blade work just as well?......Todd
Chipbreakers
Eric Hedberg
>I don't argue that chip breakers can break chips like those on the thick shavings from pine used in rough carpentry. I would argue, though, that as blades became thinner (stamped steel to cut costs) chip breakers became more important to hold the blade firmly against the edge of the bed than to "break" a chip. As to the curve on the chipbreakers of the later Stanley's, it is a good way to make a thin piece of metal act like a spring and apply force to the edge of the blade. It also lets you stamp and form the chipbreaker out of inexpensive metal sheet stock. If you want to use a thick chipbreaker, you need to do what Hock has done with his improved chipbreakers and grind a small hollow on the back and put a "burr" at the edge. It's a stiffer and more expensive solution, If the force isn't evenly along the front edge the blade will chatter (not to mention wood that gets caught in gaps). I suspect that even if they are "stiffeners" no one would call them that as the metal clamped to the blade started with the name "chipbreaker". Besides, don't we clamp the blade to a frog anyhow?