# Kiln shelf stacker

Kiln shelves are brittle and should be stored standing on their edges. Some furniture was required to store three circular kiln shelves. I built it using scrap wood.

# Design

I had some rough-sawn softwood boards of width 12 cm and thickness 25 mm, recovered from a palette. The circular shelves were of diameter 350 mm and thickness 10 mm. I calculated that if I used the boards to create slots with width 15 mm, the centre of gravity of the shelf would still fall within the slot. I also allowed for a base, made from wider 25 mm timber, that was about 3 cm wider than the combined width of the slots. I expected the design to be stable.

I had some spare 9 mm diameter dowel. I planned to pass the dowel through the slot boards about 10 cm from the base, both to constrain the shelf and strengthen the structure. The length of a chord is given by $$2\sqrt{r^2-d^2}$$, where $$r$$ is the radius and $$d$$ is the shortest distance from the chord to the centre. Here, the radius is 175 mm and the distance is 75 mm. The chord is about 316 mm. I allowed a tolerance of about 4 mm.

# Construction

I cut four slot boards of length 36 cm. I clamped the boards together to drill the holes (diameter 9.5 mm) through all the boards for the two dowels. Drilling was not straightforward; I drilled a sequence of holes with increasing bit diameters but should have started smaller and taken smaller steps between bit sizes.

I placed the dowels (without glue) and glued and screwed the slot boards to the base, using 15 mm lengths of dowel as spacers. I then fixed the dowels with glue, again using dowel spacers until the glue was set. The rough wood edges required a lot of sanding to make them smooth.

Strips of foam were placed in the centre of the bottom of the slots to further cushion the shelves as they were placed.

# Result

The result was as I intended: a stable rack for the kiln shelves.