A Dun Solution

I needed to make the ends of a dun shell perpendicular to its axis, ie, at right angles to the sides. The shell is hand hewn and therefore less than a perfect circular prism so merely lying a 'square' along the outside of the shell wouldn't quite do. Here's the solution I came up with:

I envisioned something pliable but with structural integrity. A sheet of metal was an option but that meant going out and buying some. I have this sheet of plastic material leaning up against the wall of my garage to protect my expensive road bike. It's a sign obviously and I took a piece off one corner - I remember now, to make a number plate for the bike rack on the car.

The principle is that the sheet of plastic wrapped around the dun pretty much can't but conform to the shape of the shell, the ends being more or less - an average so to speak - perpendicular to the axis.

The pencil line made using the edge of the plastic sheet as a reference shows how much material at that point needs to be removed to make the end 'square'.

Here's the shell after the ends were planed flat and roughly shamfered. The shell will be further finished with a spokeshave, sanded then oiled. Next comes the job of fitting the skins.

The plastic sheet returned to its original flat shape after a few minutes and is happily back doing its job for the bike.

The whole process of marking up, planing and cleaning up took about half an hour - that's efficiency!