Volume Calculation. Let’s start with the volume calculation. It turns out the cremation process removes all the water – about 60% of body mass. Then, the heat reduction of the other elements results in about 1 cubic inch of material per pound of body weight. So, a person weighing 180 pounds requires about 180 cubic inches inside their cremation casket or urn. One final word – don’t go overboard, but it’s probably better to error on the high side – well, just in case…
Here’s a formula you can use – it’s just a bit of simple algebra:
L x W x H = V – that is – Length x Width x Height = Volume. An applied example for, say, 180 cubic inches might be 5 x 4 x 9 = 180. Knowing this, you can increase or decrease the length, width and/or height to adjust the volume of your casket. Our example in this article is 5 x 5 x 9-1/2 for a total of 237.5 cubic inches.
Material Selection. For this article I’ve chosen quarter-sawn sycamore from my shop. You can choose any quality wood – the higher density of hardwoods makes the most sense. Don’t forget this project will result in a piece of furniture that might be around for many years. Keep in mind the project takes only about 4 or 5 board feet of lumber – no reason to skimp on materials.
Cut List and Materials:
- 2 ends – 3/4″ x 5″ x 5″
- 2 sides, front and back – 3/4″ x 9-1/2″ x 5″
- A bottom – size calculated below.
- 2 pieces for a double stacked top – size calculated below.
- 4 corner pillars – 1-1/8″ x 1-1/8″ x 5″ – these could be optional if you choose some other sort of corner joinery.
- 8 splines to bolster the butt joints where the sides and ends meet the pillars.
- 4 each 5/16″ x 3/4″ long dowels for use as alignment pins.
- 16 each 1-1/4″ wood screws.
A few notes about the top and bottom – I make the bottom about 3/4″ wider than the outside dimensions of the casket frame. So, for the long dimension of the casket frame you have:
1-1/8″ + 1-1/8″ + 9-1/2″ = 11-3/4″. Adding 3/4″ for each end gives you a bottom length of 13-1/4″…and for the width of the bottom:
1-1/8″ + 1-1/8″ + 5″ = 7-1/4″. Adding 3/4″ for each end gives you a bottom width of 8-3/4″.
The top overlaps the casket frame by 1/2 as much as the bottom, extending 3/8″ beyond the outside of the frame on each side. The second top piece is the size as the outer dimensions of the cask.
Of course, you can decide for yourself how these dimensions relate – please keep in mind that the dimensions of the two top pieces play a particular role in assembly – please read on before you start cutting.
Material Preparation. Once the bottom, top and frame pieces are cut to size, sand 180-grit. Look carefully for any latent sanding marks – they’ll show up through the finish. (You will have one more sanding step after routing is done.)
I keep the pillar stock in one piece for milling on the router. I use a biscuit slot cutter bit for the spline slots and a 1/2″ roundover bit for the outside edge of the pillars.
Note – you have to set the slot cutter high enough to ensure you don’t overlap opposing slots – thereby making it a rabbit instead of a slot.
Next, cut the pillar pieces to length. Finish sand all parts. I sand to 320 grit.
Truing the Top and Bottom Edges of the Frame. Once you remove the clamps, check the top and bottom edges of the casket frame for uneven spots. If you have high spots, it’s important to flatten them so the top and bottom frame edges fit tight and flush against the top and bottom. One method for flattening high spots is to attach some PSA sandpaper to a dead-flat surface and rub the edges over the abrasive until any high spots are eliminated.
Here’s what it looks like on the inside.
Finishing. Remove the bottom from the frame. Apply 2 or 3 coats of polyurethane, lacquer or other finish of your choice to the inside of the frame and top. Once cured, finish the exterior surfaces. Let the whole project cure completely and reassemble. When ready to introduce the contents, simply remove the bottom and place the contents inside. Run a thin bead of silicone sealer along the exposed edge of the frame, position the bottom using the dowel pins for alignment, then, screw the two pieces together.
Footnotes. I recently had a request from one family for 6 identical caskets. Identical except for the names engraved on them. The names were laser engraved. Think of the possibilities – an emblem from military service, something related to a favorite sport or activity or a favorite saying.
I also attach felt dots as feet to the bottom.