I am early in my woodworking “career”, and I recently purchased the 50 degree blade for my trusty Lee Valley low angle Jack plane. It seemed to function fairly well over the weekend as I was smoothing some cherry boards. What are the relative merits/disadvantages between this and a conventional smoothing plane (I have been looking at the Lie Nielsen 4 1/2 for a comparison)? Other than the length (which I suppose is the key factor), they are about the same weight and the same width of the iron.
First of all smoothing planes are part of a family of planes we commonly and very distinctly refer to as bench planes. These are bevel-down planes ranging in length from around 5″ to 24″. New planes now being made and sold as bevel-up planes are not bench planes and generally cannot be used in the same way or for the same task range as the bevel-up planes. They can of course be called by the same names, ‘smoothing‘ planes, ‘jack‘ planes and so on, but they are not the same in the hand, on the job or in what they are generally used for. They do have their place in the shop and on the bench, but they are different.
I am not sure if there is a need for a 50-degree bevel iron as such. This is one of those situations where I might consider an increase in bevel angle by adding a micro bevel on a regular iron, which is usually best at 30-degrees, to increase the angle of presentation to the wood. This is of course for the bevel-up planes we are taking about. It is not necessary to use a 50-degree iron on a regular basis nor to use a bevel-up plane, which is very limited in its function for normal bench plane use. The bevel up plane is not a bench plane as such but more a mitre plane revamped under a different name. Essentially it is the same plane.
I think it’s important to see that the bevel up plane is always described by the makers as, 1, a low-angle plane, 2, a bevel-up plane, and 3, having a 25-degree bevel. Configuring the numbers this way, they then present the plane as a different plane to a bevel-down plane, citing the difference mainly as the low blade angle and the lower bevel. Even so, a 25-degree bevel is weaker and more prone to fracture and the better bevel will in practice and in everyday work be 30-degrees. At the end of the day there is 5-degrees difference between the two conventional bevels. Add the 12-degree bed angle to a conventional 30-degree bevel and you have either 42-degrees or 37-degrees if using 25-degrees. Not too much different but a little. I have tried both and cannot really discern the difference. Lowering the angle of presentation does affect the iron very directly however. The lower the angle the less leverage there is along the cutting edge as the plane is forced into and along the grain. The low angle plane will stay sharp longer because edge fracture is reduced. Much of the problem I see now is that, whereas the bevel-up plane will resolve the issue of planing tangentially to the axis of the grain as in mitres and end-grain planing, it copes very badly with the slightest rise in grain in opposing direction and it’s here that difficult grain triumphs. When that does happen, half the wood you are planing tears rather than cuts and usually these tears are two to three times deeper than the thickness of the shaving taken and repairing the damage is major. I think perhaps Veritas offered the 50-degree bevel to counter an introduced problem in offering the bevel-up plane as a bench plane. What I am talking about is not at all a rare occurrence but a common one. Trees don’t grow straight grain much of the time. There are in general two accepted reasons for the increased bevel angle or bed angle that present the cutting edge at a steep angle. One is for use on burly, awkward-grained woods where often the material is almost standing perpendicual to the axis of the board being planed. This is rare and usually we rely on scrapers for this type of wild grain and less so on planes. The other is certain hard woods as distinct from hardwoods work exceptionally well with a 50-degree bevel whether it’s the large face of the iron or the bevel that’s presented to the wood’s surface – that is, bevel up or bevel down. Rosewood, ebony, boxwood and many others would be considered hard, dense-grained hardwoods with minute and tight cells. These are the type of woods that work well with steeper bevels.