Re: handle ergonomic considerations
Lyn J. Mangiameli
>There is so much to say about handles, as the bench plane handle performs more than one task (general handling and lifting the plane from the wood, guiding the orientation of the plane, and serving as the means to translate the driving force of the body into propulsion of the plane are just some prominent examples).
General handling and lifting require handles that allow for a good grip in opposition to gravity. The front mushroom tote of the new LA Jack serves this function well, while many wooden plane and toteless infill gripping surfaces are rather lacking in this area (fortunately most wooden planes are relatively light, but not all). Extended planing is going to involve a lot of lifting of the plane from the wood, so to avoid fatigue, an efficient lifting (handle) system is important.
The ease with which guiding the orientation of the plane is achieved is greatly due to handle configuration. Guiding the plane means establishing the direction of the motion and the skew (or lack of) the plane, maintaining orthogonality when jointing an edge or achieving a constant angle for champhering, etc. This may involve (say when skewing the plane, or working from the side of the workpiece) approaching the plane at some angle from the side. To do this comfortably, one must be able to grasp the handles from more than one postion, all the while being able to stay clear of other portions of the plane (say the side wings of a Bedrock style) while clasping the handles. It often means the grip on the handle must allow for some encompassing of the handle by the hand, rather than an open grip that is largely maintained by driving pressure.
Perhaps the most obvious, but often neglected aspect of handles is that they must allow for a physiologically efficient means to translate body forces into propulsion of the plane. This usually means allowing a comfortable grip of the handle while the wrist, hand are in line, which directs the forces in line with the bones and their jointing surfaces, and where this is not possible, emphasizes the forces arising from the most functional use of the larger muscle groups. These forces primarily need to be directed towards forward motion, but may also need to be directed towards the wood surface as well.
Achieving optimum direction of force is no mean feat, as bench and body heights differ, as does body mass and muscle strength. A person using a high bench, but also being tall and with great upper body strength is going to interact with a plane differently than a person with a high bench who is shorter, has less upper body strength, and less upper body mass.
Low bench heights were used in the past when much of planing was performed by shorter (though often more muscular)men for the purpose of extensive dimensioning as well as smoothing and jointing. Low bench heights are still desirable for dimensioning tasks, and/or for those with less upper body strength and mass, as it allow one to get more of the upper body mass up over the plane, and allows the use of that mass (as well as muscle forces)to help drive the plane.
However, a high bench has some advantages, not the least is better visibility and fine motor control when edgejointing. Taller persons with more upper body strength are going to be more comfortable (as a general rule) with a taller bench.
These are just oversimplified examples (some of you have read my long version of handle and planing force analysis), but I think they begin to demonstrate why any single handle design is hard pressed to achieve any universality of application. A more angled tote, such as is found on L-N planes and others of the Stanley tradition, tends to work better ergonomically for those using a low bench for tasks the require more force than finesse (again, dimensioning, so for Jacks and the like), while a straighter tote tends to be more desireable for use with a taller bench where the task require good visibility and control (say a #7 edge jointer). So one of the things I try to encourage is not using exactly the same handle style for all plane sizes. And while this will be difficult to achieve for many, it is actually desirable to have benches of more than one height, and the planes that match.
Again, there is so much more to say, but I hope this give one some idea of why I don't think there is any one perfect handle style, even for the same person. It hopefully also gives some idea why there will be disparity of opinion between hand tool users on what is the optimal handle shape and angle.
