|Project by bobkberg||posted 01-31-2015 10:11 PM||1536 views||3 times favorited||1 comment|
The previous project got me curious about different pitches for a drum, so I decided to try making one with two major diameters to see what difference it would make. Additionally, I wanted to make something that could sit on someone’s lap without being muffled on the lower head by clothing.
So I set out to make one in a shape I’d never seen before. Additionally, to save money I chose poplar, a nice hardwood, but often greenish in color. Then decided to celebrate the green!
Thanks to Loren of lawoodworking, calculating the angle for the two sets of staves was a piece of cake.
What was interesting (see photo 2) was figuring out how to clamp a curved section to a straight section. You can ignore the “stepped” sections in photo 3 – I was going to have sides that came down lower on the outside of the player’s legs, and then abandoned that idea and just cut the whole thing to the same height.
To keep the bottom head from being muffled by the players clothing or legs, I decided to set the bottom head an inch up from the actual bottom by bending thin strips of oak and gluing them to the inside of the drum. That used up darned near every small clamp I had of various types. Once that was dry and sanded, I cut the inner drum head close to exact size, but a trifle larger and began fitting it in by sanding it bit by bit on a drum sander on the drill press so that I could get the closest possible fit. The bottom head was then held down for gluing by the clamps seen and turned out quite nicely.
Since I wanted everything nicely sealed, I laid the drum form down on the pre-sanded (150, then 180 grit) 3mm birch plywood and outlined the inside and outside with a pencil. Then I painted on the sanding sealer (Zar oil-based poly sealer) to just within the inner line. Let dry, sand, second coat.
Gluing on the top was the simplest part. After running the form through the table saw against the rip fence to get a clean edge for gluing, I laid the drum body down on the top (to the pencil lines) with generous amounts of glue, then put a piece of plywood on top of that, and two 25# sacks of buckshot to hold it firmly in place on the cast iron table saw. This had also worked nicely for the first Cajon. Overnight dry, round-over router bit for the edging and then more sanding and finishing.
To reduce or eliminate the brushing sound when fingertips go across the top sideways, I sanded the 3 coats of poly with #400 grit paper down to a smooth finish and finished again. There is still a slight brushing sound, but almost none. Since this is an experiment, I’ll leave it be for the time being.
I’m going to have some of my musician friends check it out. I’ve gotten overall positive feedback for the first one. This second one is definitely experimental, but there is a difference in pitch between the larger and smaller diameter ends, so it’s at least a partial success and a good learning experience.
-- Bob www.singularengineering.com - A sideline, not how I earn a living