In the series to date we’ve looked at a basic construction and grain orientation for a simple Continental-Style boarded chest. Today we’re going to have a go at a common period innovation that improves structure, longevity, and visual appeal through a method called “Boot Jacking.”
The basic bootjack is named after a tool used to help put on a pair of boots. A triangular shape is sawn out of the end boards along the bottom edge to create this effect. It is most convenient to cut this kind of pierce-work before a chest is assembled. Laying out a basic bootjack is relatively simple.
Start by marking the middle of the boardface along the width, and then the mid-point between the shoulder and the bottom edge of the board. Striking a mark where these two intersect determines the height and center point of the bootjack.
From the intersection of the two original points, mark two additional points midway between the centerpoint and end corners on the bottom edge of the board. Strike a line each from these “quarter” points to the vertex that makes the peak of the triangle.
Repeating this process on the other side of each board makes it very easy to saw a “square” and true cutout on the foot of the end boards.
Now, other than looking a little prettier, what does this do?
The bootjack’s function is many-fold. In support of durability, a bootjack shears diagonally across the end grain which resists splitting. The long edge of endgrain that spans a solid “foot” of a boarded chest is prone to significant movement. Being a free-moving, checks and cracks along the grain are likely. Such a split can prematurely end the useful lifetime of a boarded chest. The other improvement a bootjack provides is in stability. A solid foot spanning the width of the end boards provides two points of contact with the ground below it. On flat surfaces, this is no great concern. On uneven flooring, the bootjack provides a more stable base by doubling the points of contact to four. Ask anyone with military experience the importance of the “fourth point of contact”.
I’ve mentioned in previous posts the three aspects of design as described by Vitruvius – Duritas, Utilitas, Venustas? Well, a bootjack, even a simple one, adds to all three of these aspects, Durability, Utility, and Beauty, in a boarded chest.
While we’re here, lets look at a few more interesting types of bootjacks. Lets see what we can do with a Simple Arc and a Keyhole.
For each one, we’ll start with the same layout for finding the peak of the bootjack.
From the centerpoint of the “foot” we will scribe an arch with a radius equal to the height of the apex mark. You did bring your dividers along for this exercise, yes? They’re going to become very useful. Marking both faces and continuing the lines across the edge of the board will certainly make it easier to cut this arc consistently.
With a coping saw, turning saw, bandsaw or whatever implement of destruction appropriately fits your fancy, saw out the arc on both end boards and get on to completing the construction.
The keyhole is effectively the fastest of all options. Using out basic midpoint to midpoint layout, we’ll bore a nice large hole at the vertex… something on the order of a 1″ diameter. Then with a saw that has a fairly thick kerf, cut straight “up” the line struck from the foot of the board to the hole that has been bored. If all you have are thin kerf blades, making multiple cuts on either side of the mid-line can widen out that space.
Or we can merge the triangle bootjack with the keyhole bootjack to create something with a little more visual interest.
Next time, we’re going to drop a little Gothic on these bootjacks to see how far we can go with a simple construction.