This is the second part of a multi-part series on making a moulding plane. If you’re just finding this blog post, please see the first part of the series here.
As I mentioned in the first part of the series, I highly recommend the DVD Making Traditional Side Escapement Planes with Larry Williams. This is a phenomenal educational tool for anyone interested in making moulding planes and some of their history.
We ended the part one of the series with a wooden blank for the molding plane that is 11″ x 3 1/2″ x 21/32″.
The first step in laying out the plane is to mark a 1/8″ section at the top of the grip. This will be the top of the finished plane, but for now we have a little extra material that can get beat up while we make the plane. While we’re at it, mark a what will be the ends of the finished plane. The finished plane will be 10″ long, so mark the layout lines about 1/2″ inch from one end and then measure out 10″ and mark the other end line.
Next, we need to layout the grip for the plane. On the finished plane, the grip is 1 1/2″ from the top of the plane and is 1/2″ thick. To make the grip, we’ll be removing a 5/32″ x 1 1/2″ section on the escapement side of the plane. As a reminder, the escapement side is on the left if the toe is at the front. It should be the opposite face from the reference face you marked when you milled up the plane blank.
I made a mistake when I was laying out the grip on my plane. I marked 1 1/2″ down on the blind side of the plane. I guess I’ll have to live with a cutting gauge mark along the blind side of my plane. If you do mess it up, it won’t hurt anything.
Once this is done, it’s time to lay out the back of the mouth of the plane. This will be located 3 3/4″ from the front end (the toe) of the plane. Measure back from 3 3/4″ layout line that will be the finished toe of the plane and mark a line at a right angle down the sole of the plane to indicate the back of the mouth. The mouth will be 3/8″ from the escapement side of the plane.
When the back of the mouth is laid out, we can mark the line that will be the bed of the plane. I have a layout block that I use to mark this angle. The bed angle you want will depend on the type of wood you will be working with the plane. For softer woods, an angle of 45 degrees (common pitch) is good; for a mix of harder and softer wood, 50 degrees (York pitch); for hard woods 55 degrees (middle pitch); and finally, for figured grain or extremely hard woods, a bed angle of 60 degrees (half pitch) is appropriate. The higher the angle of the bed, the faster the edge of the plane iron will wear and the more frequently it will have to be sharpened. The planes I’m making are bedded at the 55 degree (middle) pitch. When laying out the bed angles, make the initial layout 1/2 degree less than your target angle. This will give you a little extra material to work with when you are bedding the iron. My layout block has the right side cut at a 54 1/2 degree angle for the bed (the back side of the blade and wedge mortise). The left side is cut with a 65 1/2 degree angle for the breast (the front of the mortise.
I line up the right edge with the layout line for the back of the mouth and then use a marking knife to cut in the bed angle.
Next, I use a 1/10″ chisel to mark the front of the mouth of the plane.
Sketch-up doesn’t like 1/10″ increments. 3/32″ is a close approximation.
Using the left side of the layout block, I layout the breast angle the same way I did the bed angle.
This angle should be 65 1/2 degrees.
If we use the point where these two lines end at the top of the plane, we can mark squared lines across the top of the grip. The space between these two lines will be the front and back of the wedge mortise.
Next, lay out what would be the center of the grip. This should be around 1/4″ from the blind side of the plane. If your grip isn’t exactly 1/2″ thick, you’ll want to make sure you mark the true center of the the grip. You’ll be using this line to layout the width of the wedge mortise.
The thickness of the wedges of moulding planes varies based on the size of the cutting profile of the plane. For a # 6 plane, the wedge thickness is 3/16″. We need to layout the walls of the mortise 3/32″ from each side of the center line. Check before the final layout lines are marked to make sure you are at 3/16″ total thickness.
You should run the layout line for the blindside of the mortise down the length of the grip and the toe and heel of the plane to help with the layout.
Because the wall of the mortise on the blind side is so thin, moulding planes use what is called a leaning wedge. Basically, this means that the mortise is cut at an angle so that the wall is thicker at the sole of the plane than at the grip. At the sole of a # 6 plane, the wedge leans at about 1/8″.
When determining the actual amount of lean , you need to know that the back of the mortise, the leaning line you just marked should be exactly the width of the plane profile from the escapement side of the plane. A # 6 plane cuts a 3/8″ profile (1/6 of a 3/8″ radius circle), so the end of the leaning line has to be exactly 3/8″ from the escapement side of the plane, even if it is less or more than 1/8″. Mark the lean on both the toe and heel of the plane.
Now we can layout the target profile of the plane. This plane is a hollow plane (it has a convex curve). A round plane has a concave profile. The size of the plane determines the width of the profile and the radius of a circle that it cuts. These planes cut a 1/6 radius of a circle. Based on the magic of geometry, the width of the plane profile is equal to the radius of the circle the plane cuts. I laid out the profile of this plane using a plastic circle template, using a 3/4″ diameter circle.As with the lean of the wedge, mark the profile on both the toe and heel of the plane.
Finally, these planes have a clearance angle cut along the blind side of the plane to allow the plane to get into tight spaces. This angle is 60 degrees off the sole of the plane from the edge of the profile to the blind side of the plane. For a hollow plane such as this one, the relief angle will run along the sole of the plane 3/8″ from the escapement side of the plane. For a round plane, the angle starts higher up on the body of the plane where the curved profile ends. Mark the relief angles on both the toe and heel and mark the line where the relief angle meets the blind side of the plane and extend this line down the length of the blind side of the plane.
There you have it – all the major features of the plane are laid out. There are a lot of steps in laying out a plane, but none of them are difficult or require any extraordinary level of precision.
In the next post, we’ll walk through the process of cutting the escapement and sinking the mortise of the plane.
Until next time. . .