One of the number one questions I get is about the differences between segments and stave shells and why I almost exclusively stick with segments. There are almost as many competing ideas on the issue as there are drum builders, but here are this drum builder’s thoughts…
Horizontal Vs. Vertical Grain
The main difference in these two types of shells is the direction of the grain. Stave shells are built with the grain running vertically from top to bottom of the shell, segment shells are built with the grain running horizontally. While that might not seem like a big difference it makes all the difference in the world for one major reason – solid wood is constantly expanding and contracting. It’s a fact of life and there’s no way to stop it.
Movement in Solid Wood
As changes in humidity occur the moisture content in any solid wood will change, causing it to expand and contract. The expansion and contraction always happens across the grain, never lengthwise in the board. Picture a stave shell with grain running vertically – as the wood expands and contracts across the width of the board the overall diameter will change. Each piece will shrink or swell at a different rate so the odds of the shell staying truly round through this process are almost zero. I’ve seen (and built) many stave drums that were perfect when they came off the lathe and over the course of a week changed drastically in their outside dimension. The use of quarter sawn wood does help keep the movement to a minimum but doesn’t completely solve the problem and quarter sawn wood is rarely available in most wood species. For staves, a 1/16″ change in the outside diameter is typical but I’ve seen as much as 5/16″ – when I turn a shell to 13 7/8″ I want to stay that way!
Why Segment Shells Move Less
Segment shells are more stable for two reasons, the direction of the grain and the larger number of smaller pieces. When a segment shell expands and contracts it will happen over the depth of the drum, not the diameter. The horizontal grain means that the diameter of the shell will not change and it will stay round, that means your heads will stay seated the drum is allowed to resonate like it should. The brickwork patter of the segments also locks the pieces together – each piece has less room to move since it’s locked in on all sides by the other pieces.
Rigidity and Durability
The brickwork pattern and horizontal grain of segment shells make them more durable and rigid then staves. A more rigid shell can be turned thinner without the use of reinforcement rings. I feel comfortable turning a segment shell down to 1/4″ thickness but I’ll never go past 3/8″ on a stave. Thinner stave shells are even more prone to movement with humidity and more likely to split down the grain or at the glue joints.
Stave shells can be made to look more like a single, solid piece of wood then segments which a lot of people prefer. I find that I can be much more creative with segments. There are a million different ways to combine woods for new and interesting looks and sounds, not to mention the doors that open up for contouring with segments.
The main difference is in the pitch. Staves favor the lower end and segments favor the higher end by comparison. I also find that segments have a wider tuning range and I believe it once again comes down to the rigidity and stability of the shell.
I’m sure the stave shell purists out there will disagree with a lot of this and that’s OK with me. I believe that if we all had the same opinions on the matter there would be a lot less awesome drums out there for us to look at, drool over and hopefully eventually get to own. I welcome anyone who wants to put in there two cents to leave a comment below!