Tag-Archive for ◊ bevel-up plane design ◊

Author:
• Wednesday, July 31st, 2019
bevel-up planes

A few more points on this topic:

1. If you had a BU jack plane with a 20° bed, could you still use it on end grain? Sure. My Lie-Nielsen #9 “iron miter plane” has a bed of 20° and it works wonderfully on end grain, and so does my L-N shoulder plane with a bed of 18°. Perhaps this is so because resistance is indeed determined solely by the attack angle and not by the sharpening angle per se. 

2. This is not about block planes, which, of course, also happen to be bevel-up. It is about BU smoothing planes and, to a lesser extent BU jack planes. Incidentally, I suspect one reason for the popularity of 12°-bed block planes over 20°-bed models is that the former are more compact and thus easier to manipulate with one hand. 

3. This is not just a theoretical discussion. BU planes with 20-22° beds have been designed and are available from distinguished planemakers. Take a look at Karl Holtey’s #98 Smoother. Philip Marcou offers bevel-up smoothing and jack planes with 15° and 20° bed angles. [Drool, drool . . .] Though not it’s intended to be used as a smoothing plane, I’ve experimented with setting up my L-N #9 (20° bed) as a high-attack smoother. It works. 

So, what’s the point of these four posts? It is simply this: a good addition to the Lee Valley and Lie-Nielsen product lines would be, at the least, the option of a bevel-up smoothing plane with a 20-22° bed. (22° would suit me just fine.)

Author:
• Tuesday, July 30th, 2019
bevel-up smoothing plane

To create higher attack angles, such as 55°, to reduce tearout with a bevel-up smoothing plane, here are more advantages to a 20-22° bed angle versus the commonly produced 12° bed angle. 

1. A higher bed angle requires less camber in the edge to achieve a given “functional camber.” Please see my post that defines the terms I am using and explains the simple math, and this post that shows the effect of bed angle. A blade placed in a 12° bed requires about 75% more “observed camber” to achieve the same functional camber as when placed in a 22° bed. For example: you must grind .014″ camber to achieve .003″ functional camber in a 12° bed, but only have to grind .008″ to achieve the same .003″ functional camber in a 22° bed. 

Putting camber in the blade edge takes time and it’s easier to do if there’s less of it.

2. As the wear bevel develops on the lower (flat) side of the blade, an adequate clearance angle is maintained longer when the bed angle is greater. Again, I reference Terry Gordon’s article in Furniture and Cabinetmaking magazine (November 2018, Issue 276, pp. 48-50) and Brent Beach’s website.

Here are two more possible advantages to a 20-22° bed versus a 12° bed, but these are speculative.

1. For a given attack angle, the narrower sharpening angle (as would be used with the higher bed angle) may produce less resistance in the cut. I’m not sure. Maybe resistance is instead determined only by the attack angle, as has been suggested to me by a planemaker. I do not have a way in my shop of making an apples-to-apples comparison. I’d need two planes, identical except for bed angle, then make the same attack angle in each – for example, one with a 22° bed and a 33° blade (=55°) and the other with a 12° bed and a 43° blade (=55°).  

2. Perhaps the steeper 20-22° bed is an advantage in design and manufacturing in that it is sturdier and less likely than a 12° bed to deflect downward. I don’t make planes, so I don’t know.

Coming up: just a few more points.

Author:
• Monday, July 22nd, 2019
bevel-up plane blades

In the previous post, I discussed how a 20-22° bed in a bevel-up smoothing plane can produce a wider range of useful attack angles without resorting to excessively high sharpening angles. The use of narrower sharpening angles has, in turn, several advantages:

1. Sharpening is easier. It is simply more difficult to get a good, sharp edge at, for example, 43° than 33°. It is also awkward to work at the higher angles, and the feedback from the surface of the stone is not as good. I think this is readily evident but some may disagree.  

2. Based on my experience, and I think most woodworkers would agree, a blade with a very steep secondary bevel dulls faster than one with a more usual, narrower bevel, all else being equal. 

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Sidebar: how an edge dulls

The profile of the sharp edge of the blade ideally starts out as two straight surfaces meeting at a clean, sharp point. As the edge wears, steel is abraded away from the surfaces near the edge, and the original point becomes rounded over. The worn surfaces of the blade that approach the blunted edge can be thought of as “wear bevels.” Thanks to Brent Beach and Steve Elliot for their development and detailed study of these concepts.

For both bevel-up and bevel-down planes, the wear bevel on the top side of the blade (the side facing away from the wood) is wider than that on the bottom side, because it is the top (front) of the blade that bears the brunt of the collision with the wood. The bottom-side wear bevel, which is on the flat side of the blade in a BU plane, is nonetheless important.

Brent Beach explains the value of removing the lower wear bevel when sharpening to regain a truly sharp edge, to maintain proper clearance of the blade edge from the wood, and to avoid the need to apply undue pressure when planing. David Charlesworth’s Ruler Trick is thus particularly helpful for bevel-up plane blades.

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3. A functionally sharp edge is preserved longer when the blade is sharpened at a narrower angle. This is consistent with point #2. Australian planemaker Terry Gordon explains this nicely in a recent article in Furniture and Cabinetmaking magazine (November 2018, Issue 276, pp. 48-50). It is best understood diagrammatically but the gist is that a skinnier edge retains useful sharpness longer by remaining narrow longer.

In summary, there are important advantages in sharpening and edge endurance when using the narrower sharpening angles permitted by a higher bed angle in bevel-up smoothing planes.

For example, if you want a 55° attack in your BU smoother, you’re better off being able to sharpen at 33° with a 22° bed (=55°) than having to sharpen at 43° with the 12° bed (=55°) in currently offered stock planes.

Coming up: still more issues. Can you tell that I’m building a case that I think L-N and L-V should hear?

Author:
• Sunday, June 30th, 2019
bevel-up planes

Lee Valley and Lie-Nielsen both use a 12° bed for their bevel-up (BU) bench planes. At least for smoothing planes, I think there are better options. I addressed this issue in a 2010 post but now would like to add additional reasoning.

Let’s start with the issue of attack angle.

One of the advantages of BU planes is the attack angle (the angle between the wood and the leading surface of the blade) can be altered simply by changing the sharpening angle of the final microbevel. There is no need to change the frog and/or create a large back bevel (a large bevel on the normally flat side of the blade) as with a bevel-down plane. The attack angle is a key factor in how a plane functions, especially to control tear out. 

In a bevel-up plane with a 12° bed, to achieve a 50° attack angle, a good all-around angle for a smoother, the sharpening angle must be 38°. (Note that all of the sharpening angles in this discussion are only the final, steepest microbevel, which is what actually interacts with the wood.) A 55° attack, a good choice to manage most figured woods, would require a 43° sharpening angle. A 60° attack, which is about as steep as you can go before the plane acts more like a scraper but is nonetheless useful for difficult woods, requires a 48° sharpening!

Alternatively, let’s consider a 22° bed for the bevel-up smoothing plane. Much lower sharpening angles can be used. For example, a 33° sharpening angle yields a 55° attack, which is a nice setup with an A-2 blade. The 60° attack requires a still-manageable 38° sharpening. On the other hand, if you want a lower attack, you could sharpen at 28° or 30°, such as with an O-1 blade, to yield a 50-52° attack. If slightly lower attack angles suit you, a 20° bed is a good, versatile compromise.

So, a 20-22° bed angle in a bevel-up smoothing plane allows you to a create a good range of attack angles without the excessively high sharpening angles required with a 12° bed.

For a BU jack plane, the case for a steeper bed is less compelling, though still interesting. A 12° bed with a 33° sharpening – typical for an A-2 blade that would often be found in a jack – gives a 45° attack, which many woodworkers consider to be a good all-around choice for a jack. Still, a 15° bed would increase the versatility of the plane in creating slightly higher attack angles without having to increase the sharpening angle too much. 

To summarize the main point: a bevel-up smoothing plane with a 12° bed requires excessively high sharpening angles to achieve the very helpful range of attack angles that is one of the key advantages to this type of plane. 

Much more to come on this topic in upcoming posts. Those excessively high sharpening angles produce several disadvantages. Furthermore, the lower 12° bed is a disadvantage in itself, and actually lacks a traditionally-cited advantage.

Author:
• Saturday, June 26th, 2010

Bevel-up, low-angle smoothing, jack, and jointer planes made by Lie-Nielsen and Lee Valley have 12 degree beds for their blades. This style of plane is simple to set up and especially versatile. The use of a thick blade, 3/16″ or more, supported very close to its cutting edge, and an easily adjustable throat opening contribute to effective planing.

One of the most important advantages of these planes is their ability to employ blades sharpened at different angles to manage a range of woods. With the 12 degree bed, a blade sharpened with a 33 or 38 degree bevel (secondary bevel) results in a 45 or 50 degree cutting angle, respectively. Either would be a reasonable choice for general work.

To get a 60 degree cutting angle for difficult figured woods, the blade needs a 48 degree bevel. The result is effective but this makes the blade more difficult to sharpen to a keen edge. Furthermore, this is a large wedge to drive through the wood. I believe this creates more resistance at the cutting edge, making the tool cut less cleanly and harder to push, even aside from the effects of the higher cutting angle.

If the blade bed was 20 degrees, it would require a more manageable 40 degree blade bevel to achieve the 60 degree cutting angle. A 25 degree (perhaps in O-1 steel) or 30 degree blade bevel (giving a 45 or 50 degree cutting angle, respectively) could be used for tamer woods. Another point, minor but helpful, is that a blade bedded at 20 degrees does not require as much actual camber to achieve the same functional camber as does one bedded at 12 degrees. Explanation here.

I imagine a 20 degree bed would also make the sole of the plane less prone to distortion from the pressure of the lever cap. Supporting this idea, I have not found distortion to be a problem with Lie-Nielsen’s shoulder planes with their 18 degree beds, but Lee Valley’s shoulder planes with their 15 degree beds have been a problem for me, even with rather gentle tightening of the lever cap. The 3 degrees seems to make a difference.

Considering other bevel-up planes, the fabulous Lie-Nielsen #9 “iron miter plane,” which I use for shooting end grain as well as long grain, has a 20 degree bed. Block planes come in 12 and 20 degree beds. The 20 degree tools seem to work just fine on long grain. Karl Holtey’s #98 Smoother has a 22.5 degree bed, and Philip Marcou’s S20A, which is designed to use standard Veritas blades, has a 20 degree bed. I’ve never used the Holtey or Marcou but I can’t imagine they are anything less than wonderful.

I also do not think cutting end grain is good justification for the 12 degree beds on the smoothing, jack, and jointer planes. I do not think end grain requires a 12 degree blade bed and I am skeptical of even an advantage over a 20 degree bed. Indeed, my Lie-Nielsen shoulder plane at 18 degrees works beautifully on end grain.

I own the Veritas bevel-up, low angle smoother and jack and have used the Lie-Nielsen bevel up planes. While their features differ, both makers produce superb planes. It is the 12 degree bed that I question.

I am a plane user, not a plane maker, and certainly have room to learn more. I wonder if any of these makers would care to comment on this issue.