The trick to fitting wooden pieces into impossible recesses is to learn about “ticking sticks.” These simple sticks – plus a sheet of paper – can make monstrous tasks into a easy job. Here’s how they work.
“Ticking sticks” go by many names in the historical record, but they are the best technology for cutting a piece of wood to fit an odd opening. All you need to perform this feat is a pointed stick, a piece of paper and a pencil.
The basic idea is that you use the ticking stick to “record” an irregular shape onto a piece of paper. Then you use that sheet of paper and ticking stick to draw that shape on the wood. Let’s start by describing the stick. The only thing that’s important about the stick is that it be pointed at one end. Mark one face of the stick as “up” and draw a line on one of the stick’s edges, as shown in the photos. We call this line the “tick line.”
The piece of paper is almost always smaller than the opening you are trying to “record.” In this case, it’s a piece of posterboard I’ve placed inside a rotted tree trunk. I want to fit a seat inside the hollow trunk.
Touch the ticking stick to the inside edge of the trunk. With your pencil, draw a line along the straight edge of your stick. Then make a mark on your line – the “tick” – at the tick line. Repeat and repeat. Move the ticking stick along the inside of your irregular opening. The more “ticks” you make, the more accurate the final shape will be. For this project I think I made about 100 ticks – that’s quite a lot.
Now tape the posterboard to the piece of wood that needs to fit in the irregular hole. Use the same ticking stick. Place it on each line and line up the “tick line” with the “tick” on the posterboard. Now mark the wood at the tip of your stick. Transfer all the ticks to your wood.
To join the lines, use a French curve. These curves excel at joining three points, Rotate each curve until three adjacent points fall on the curve. Mark them with a pencil. Work your way all around the shape, three points at a time.
So stop saving your money for a 3D scanner. Find a stick and a piece of posterboard and you’ll quickly become an expert at this old-world technique.
— Christopher Schwarz