Plane Articles

Molding plane design considerations
by Bill Clark & Larry Williams

Proper mechanical bond in a mortise and tenon joint requires tight contact between all the mating surfaces. It's arguable that this joint is the most important single joint in woodworking and probably the most common. Those interested in the study of old tools depend on a knowledge of joinery and other woodworking techniques; most authorities have a strong background in woodworking technology. It's unlikely any serious students of old tools would lack a knowledge of this joint.

It's only natural that these people apply the properties of mortise and tenon joints to the similar wedge and mortise of a side escapement molding plane. The purposes of the two are, however, vastly different but share some similar requirements.

We first found the difference when trying to complete a full set of MOSELEY hollows and rounds. This set was missing the #12 and #15 rounds. We found, at a tool meet, a GRIFFITHS, NORWICH #12 round with nearly exactly the same features as the existing 34 MOSELEY planes. We added the GRIFFITHS to the set.

Some time later, we decided to make a #15 round and used the #15 hollow for a guide. Whelan in Making Traditional Wooden Planes, Goodman in British Planemakers from 1700 and Roberts in Wooden Planes in 19th Century America, VII all state or imply that the mortise of a molding plane is set out with a marking gauge. We have planes in our collection in which the original marking gauge lines are still visible. This is the method we used to lay out our plane.

After layout we noticed that there was a problem. The iron from the hollow was 1/8" narrower than what we would need for its mating round. It was then, that we noticed that the distance from the blind side of the plane (that side opposite the side with the escapement) was 1/8" greater to the iron and mortise at the sole than at the top of the plane. We, at first, thought that the original maker had made a mistake. We checked the other planes in the set and they all had this same configuration; even the GRIFFITHS which surely was made by a different plane maker in a different city. A check of our other planes showed that this was a common but not universal feature.

We wrote and had published an article about this in the 'Fine Tool Journal' in the summer of 1997. We've studied this more and learned more about it.

These leaning wedges offer several advantages. Probably the most important is that they are faster for a plane maker to make. The leaning wedge technique requires only three critical contact points for the wedge; at the top and bottom of the blind side and at the center, under the ramp, on the escapement side. Fitting wedges is a matter of working just under the ramp rather than two full length parallel sides.

Using this technique to pressure fit the wedge against the blind side of the mouth is also very helpful in eliminating choking.

Another important advantage of this technique is that the iron is slightly tapered in width and actually gets wider with each sharpening. This is very helpful to the user in maintaining planes that require full width irons. Hollows and rounds and fillister planes are good examples of planes which, in function, require irons the full width of the sole.

The leaning wedge technique also leaves more wood on the lower part of the blind side of the plane. This makes for a much stronger plane.

The main disadvantage of the technique is that the profile cut in the iron is, in some profiles, more difficult to keep properly located through repeated sharpening. An example is a side bead. Here the profile will move slightly toward the escapement with each sharpening, especially if the sharpening is done in relation to an assumed square end of the iron. There isn't space to fully describe this here but we're confident you'll understand with a little thought. We feel that side beads are examples of planes where a leaning wedge isn't the best approach. It was, in the past, often used for side beads and we believe that is more of a testament to the ease and speed the technique lends to plane construction.

We have a ROBERT WOODING that has the features of this technique in our collection. We don't believe leaning wedges are anything new. Our feeling is that they date from the earliest professional plane makers.