The Convex Conundrum - The Three Principles of Using Japanese Finish Planes

[Stanley Covington]

One of the key things to creating smooth panels with a finish plane is to set the cut depth extremely shallow. The shavings produced when finish planing light-colored woods should be translucent when possible, to the extent that you can read newspaper print through the shaving

Thanks Stan. Intriguing.

Your comments take us full circle back about 4 years, when fine shavings began to be displaced by the thicker shavings under a chipbreakered smoother. Very fine, translucent - read through - shavings have long been the hallmark of a well set up handplane. However, in recent years they were seen to be unnecessary if planing could be done without tearout, and indeed fine shavings were considered slow and cumbersome in terms of speed and efficiency. Of course, a tearout-free surface is not necessarily a finely finished surface. One factor that promotes faster as better, in Western woodwork, is that a finish is nearly always applied. Most, if not all, finishes will obscure differences between planed and sanded surfaces.

Posts like yours - where information provided adds a fresh understanding why we do something, rather than just what we do - can influence a lot of people to work better, with more confidence in what they do. There is so much apparently contradictory advice on the 'Net that I am sure that many fail to understand that methods are not black and white.

Regards from Perth

Derek

Derek:

Thanks for your insight. Sharp as always.

I don't follow the chipbreaker thing from 4 years ago. Chipbreaker debate threads on SC are always so silly, it seems to me, kind of like arguing whether it is better to travel to the moon by balloon or rocket, that I simply skip them.

Unlike the Kezuroukai, thin shavings, in my experience, are not the objective in making a fine cut, but are a by-product of producing a smooth, apparently flat surface with a handplane. One can of course achieve a smooth finish while cutting relatively thicker shavings, but thicker shavings mean larger changes in dimensions, and a higher likelihood of tearout, and bigger, more easily discernible ridges when using a convex blade for multiple parallel passes on wider members.

So it is most efficient to have a couple of dedicated finish planes on hand, one with a straight blade, and one with a fine convex blade, both setup specifically for taking very fine shavings. Planes setup for thicker shavings are used for dimensioning, truing, and flattening as quickly as possible. These planes will need to be sharpened more frequently, and their soles will wear and get out of wack quicker than the finish planes. The finish plane is used much less so it stays sharper longer, and the blade's setting (which take some effort to get just right, as I'm sure you know) and the fettle of the sole are ready to rock-n-roll longer. Since the shavings it takes are so thin that the first few passes won't produce full-width shaving as it smooths down ridges and cleans up tearout. But when the finish plane's work is done, the surface will be as close to perfect as a hand-powered tool can manage.

I'm certain you already know this, Derek, so sorry for preaching to the choir, but for those who find what I am writing strange, please realize that the effectiveness of taking translucently thin shavings on the last few strokes is especially clear when using the convex-blade finish plane on wide panels. Since the plane's blade cannot plane the full width of the board in one pass, steps or ridges are unavoidably generated regardless of the shape of the blade. Of course, the sharply defined corners of the straight blade will produce sharply defined ridges, while a convex blade will create less-apparent ridges where plane passes meet. But when using a convex blade for multiple passes, so long as the radius of the convex curve (or radius just at the blade's corners, if you prefer) is very large (a very shallow radius), and the shavings taken are very thin, most people in most circumstances are unable to see or feel the ridges.

Where the convex blade is not an issue, thinner shavings are simply weaker than thicker shavings and have less leverage to induce tearout, producing a smoother finish.

I hope this makes sense.

Stan

[Derek Cohen]

Of course, the sharply defined corners of the straight blade will produce sharply defined ridges, while a convex blade will create less-apparent ridges where plane passes meet. But when using a convex blade for multiple passes, so long as the radius of the convex curve (or radius just at the blade's corners, if you prefer) is very large (a very shallow radius), and the shavings taken are very thin, most people in most circumstances are unable to see or feel the ridges.

A corollary of this is the way a smoother blade is cambered: too little camber and one creates tracks; too much camber (such as when only the centre third of the blade produces a shaving), then it will be difficult to avoid a sculpted surface. The aim is to take as near full width as possible.

Stan, do you have a method you can share?

Regards from Perth

Derek

[Stanley Covington]

QUOTE=Phil Mueller;2611833]Well, I'll be Stanley. I did not realize there was the option of leaving bare wood. I guess I've been exposed to so much about finishes, I just assumed it was "required". Wouldn't bare wood be highly subject to moisture, sweating drinks, spilled food, dents, etc? Or is bare wood only left for low use furniture?[/QUOTE]

Yes, bare wood is indeed an option. If you have been to Japan you have seen it. Even if you have not visited Japan, you have no doubt seen photos of high-end wooden interiors with exposed wooden beams and columns, trim, and ceilings. These are bare wood, as are the shoji and wooden doors and window frames. A planed finish has the wonderful smell, and great feel of natural wood, and ages gracefully. That does not mean it won't get dirty and doesn't need to be maintained.

The better sushiya restaurants frequently have thick counters for clients to sit at made from bare hinoki. These are of course stained daily with food and beer and sake and soy sauce, but are absolutely immaculate, and kept that why by daily cleaning with a damp cloth and a bit of baking soda as an abrasive.

Notice the adzed column in the pic below. Very old and black with stains and smoke, but still beautiful IMO.

This link shows a couple of other ways of using bare wood. One is the adzed finish. The other is the yariganna, or "spear plane" finish. More rustic, but still very cool IMO. http://www.konarahouse.jp/blog/archi...2011/09/page/4

A few pics. The temple with all the carvings is Taishakuten located here in Tokyo, and one of my favorites. Established in 1692, the carvings are bare keyaki (zelkova) and have been exposed to the elements (under eaves) for a long time.

Hatsuri hashira1.jpgFukujurou.jpgShaving1.jpgkatsura.jpgTaishakutengate.jpgTaishakuten1.jpg

[Stanley Covington]

A corollary of this is the way a smoother blade is cambered: too little camber and one creates tracks; too much camber (such as when only the centre third of the blade produces a shaving), then it will be difficult to avoid a sculpted surface. The aim is to take as near full width as possible.

Stan, do you have a method you can share?

Regards from Perth

Derek

Allow me to add one more point to your corollary. It is neither time efficient nor cost effective to spend time and money on a quality blade of any width if the entire width of the blade cannot be used for planing wood. Therefore, in the case of a finish plane, the radius or curvature of a convex blade's cutting edge needs to be very shallow indeed.

The way I was taught to make this curvature is to first begin with a sharp, straight blade on a truly flat medium-grit stone. None of this hollowed-out stone or profiled steel plate nonsense, at least not for a finish plane. Then the blade is rested half on and half off the medium grit stone's edge, and pushed forward while at the same time sliding the blade sideways until just a few millimeters of the blade are supported on the stone. Both right and left sides of the blade must be worked to the same degree of force and number of strokes. The point is that the center of the blade spends very little time on the stone. Only a few strokes are necessary. It takes practice to train the muscles.

This process is repeated on the finish stone.

Finally, center the blade on the finish stone and make multiple strokes with the entire width of the blade on the stone, while shifting pressure across the blade's cutting edge. This will help to smooth things out. Once the blade is shaped this way, it will not need to be repeated until it dulls enough to warrant time on the medium stone.

The blade should project from the dai's mouth full-width, and apparently straight (but actually slightly curved) until it curves up into the mouth. Once again, this is the case of a finish plane intended to cut translucent shavings, not arashiko or nagadai planes for dimensioning and smoothing.

Stan

[Patrick Chase]

Well, I'll be Stanley. I did not realize there was the option of leaving bare wood. I guess I've been exposed to so much about finishes, I just assumed it was "required". Wouldn't bare wood be highly subject to moisture, sweating drinks, spilled food, dents, etc? Or is bare wood only left for low use furniture?

I think Stanley is mostly referring to exterior use here. Wood is indeed susceptible to all of the things you list, but it's also amazingly resilient as long as the exposure isn't continuous.

Stanley, it occurs to me that even with a perfectly planed surface grain will be slightly raised upon first exposure to water, and that will compromise that nice smooth surface. Do you explicitly deal with that somehow, for example by wetting the wood, allowing it to dry, and then taking a *very* light smoothing pass?

[Stanley Covington]

I think Stanley is mostly referring to exterior use here. Wood is indeed susceptible to all of the things you list, but it's also amazingly resilient as long as the exposure isn't continuous.

Stanley, it occurs to me that even with a perfectly planed surface grain will be slightly raised upon first exposure to water, and that will compromise that nice smooth surface. Do you explicitly deal with that somehow, for example by wetting the wood, allowing it to dry, and then taking a *very* light smoothing pass?

No, quite definitely interior use as well.

Indeed, a bit of moisture will take the sheen off the wood, but there is no fuzz to rise up if the wood is carefully planed. One does not typically wet the wood and then take another pass as is common when trying to create a smooth surface sans fuzz when sanding wood. If tearout is a problem, wetting the surface will help a lot, but the final finish planing needs to be a dry surface.

Stan

[Stewie Simpson]

No comment.

[Stanley Covington]

No comment.

A wise decision.

[Mike Holbrook]

I believe my work may reflect some of the principals Stan is referring to as well. Most of my plane blades have less camber over the entire edge, with the exception of the corners, lately. I plan to try the sharpening technique mentioned above to better manage the camber on both sides of my blades.

On the other hand, I am interested in rougher curved surfaces. Chair legs, rungs, chair spindles, carved chair seats may not have "flat" surfaces. We may make a cylindrical surface flat along its surface, but it may be challenging to do this with a straight blade in a traditional plane. A straight blade set at an angle within a wood cylinder may accomplish this task, like the Lee Valley tenon cutters and tapered tenon cutters. I wonder how a Japanese woodworker approaches curved surfaces?

I am interested in the adze and spear plane shown above, but maybe this moves off topic?

[James Pallas]

Stanley, All very interesting. im sure planing is just part of it. Wood selection, how surfaces are prepared to shed water, grain orientation, all play a part in longevity. I hope this conversation can continue without the interjection of east vs west or the need for speed. How a plane is prepared for a very particular use was the opening post so in that vein. How many planes of the same type and size with different blade preparation are used? I'm seeing several planes with different blades and possibly the plane body prepared differently. Is this the case?
Jim

[Stanley Covington]

I believe my work may reflect some of the principals Stan is referring to as well. Most of my plane blades have less camber over the entire edge, with the exception of the corners, lately. I plan to try the sharpening technique mentioned above to better manage the camber on both sides of my blades.

On the other hand, I am interested in rougher curved surfaces. Chair legs, rungs, chair spindles, carved chair seats may not have "flat" surfaces. We may make a cylindrical surface flat along its surface, but it may be challenging to do this with a straight blade in a traditional plane. A straight blade set at an angle within a wood cylinder may accomplish this task, like the Lee Valley tenon cutters and tapered tenon cutters. I wonder how a Japanese woodworker approaches curved surfaces?

I am interested in the adze and spear plane shown above, but maybe this moves off topic?

I have little experience doing what they call "round work" in Japan. As I understand it, the lathe is the most common tool nowadays. The traditional tool is the wooden-bodied plane curved in various ways and a corresponding blade made to fit the required curvature. I have these planes and have used them for architectural work, and furniture moldings, but not to make chairs.

An adze is an adze. A useful tool, but one that requires real skill and trained muscles to produce a top notch decorative finish. I suggest you sharpen it well and use it a lot.

Yariganna, or spear plane, is a very interesting tool and fun to use if you are working on the right kind of wood. They are not easy to find.

Stan

syuru5.gifutimaru.jpg

[Stanley Covington]

Stanley, All very interesting. im sure planing is just part of it. Wood selection, how surfaces are prepared to shed water, grain orientation, all play a part in longevity. I hope this conversation can continue without the interjection of east vs west or the need for speed. How a plane is prepared for a very particular use was the opening post so in that vein. How many planes of the same type and size with different blade preparation are used? I'm seeing several planes with different blades and possibly the plane body prepared differently. Is this the case?
Jim

I hope someone will give me a million bucks, but I won't hold my breathe.

If you don't think like the interjection of East vs West, I suspect you are the minority. If you don't like to hear about speed, then you should avoid all of my posts, because working speedily and efficiently is a very important aspect of true craftsmanship to me.

I don't think I follow your questions. I mentioned two planes in the original post, both finish planes. The only significant difference between them is the shape of the blade's cutting edge. The dai of both are setup identically as finish planes.

Working efficiently and speedily are important to me, so I try to always have a backup plane ready to go. The total number of planes and their width and types and setup details will depend on the work one is undertaking.

Stan

[Pat Barry]

I appreciate your posting Stan and I think they are spot on from both practical and technical perspectives. Everything about the degree of camber on the finish blade and the process of achieving a true and finished surface is correct and well explained. I do however find the lack of finish on interior woodwork, for example: cabinets, tables, chairs, etc to be very puzzling. While I'm sure there are examples to be found that are right off the plane, it is hard to accept that finishes are not applied to improve both the surface durability and beauty. Surfaces that are touched or handled by human beings will become tainted over time due to everyday contact with sweaty / oily fingertips for example and these will stain. A fine surface such as a dining room table would be ruined without at least a wax protection. Would you agree?

[Phil Mueller]

Thanks again, Stanley. The adze and spear textured work is very appealing to me. Gives me some great ideas for a rustic piece I have in mind. May see if a similar look could be achieved with wooden rounds/hollows and/or a custom shoulder plane blade. Perhaps just a gouge. Something to play with over the upcoming winter.

[Mike Holbrook]

Thanks for the info. and pictures Stan.

The spear plane is interesting. I suspect it may require a refined skill set similar to or greater than the Adze. Like you mention the adze requires practice for good results. I have a small, for single hand use, and larger one, for use with both hands, with curved outside bevels. Used for the major stock removal in chair seats, bowls, serving dishes...I am still working on the handles and various methods for getting the most from them. The curved heads need to strike surfaces at just the right angle, which often translates into: more curved complicated handles, ways to grip those handles and ways to hold the work steady. The handle on the spear plane appears to require a handle on the opposite side of the complexity scale.

Two Adzes.jpg