Banjo bridges only need to be radiussed on top if the fingerboard is radiussed. The arch of the bridge must then match that of the curved fingerboard in order to retain proper string-to-board relationship across the board.

The most common 5-string bridge height is 5-8". Some frailers seem to favour 1-2", and some bluegrbutt players opt for bridges of over 5-8". Higher bridges tend to give more power or bite, and lower bridges seem to play 'looser'. In the end, bridge height is most determined by the angle of the neck to the body. In order to make the banjo play properly the two factors must be made to suit each other. If they aren't, high bridges will obviously make the action unpleasant, and low ones may cause unwanted buzzing.

Compensation in a banjo bridge requires that the bridge itself be considerably wider and heavier than is necessary for a 'conventional' type. That is not necessarily a good thing for overall tone.

When setting up most high-end banjos I'll pare away the sharp edges on the bridge, similar to the way a violin maker would lighten a hard bridge. For players who demand the last ounce of 'oomph' from their instrument I may also make both cheeks of teh bridge slighly concave by touching them to the end wheel on my belt sander to further lighten them.

Bridges vary hugely in sound and longevity, with the best of both produced by very hard sugar maple blanks. When selecting a bridge I'll drop a number of blanks from a set height onto a hard surface and listen for the note they make. Very good bridges will 'ping' when they hit. Duffers just sort of 'plop'.

Anyone with basic hand skills can produce a decent banjo bridge with a little practice. Personally I still prefer simple maple bodies with ebony tops, but many players have experimented with other materials.

If you want to have a bash at making a few, I can supply you with a few strips of very hard Canadian sugar maple. Living as I do in the middle of a 54 acre maple-sugar bush, it's not tough to find, and since I've made my living as a guitar and banjo builder-restorer for almost 40 years I have lots of materials hanging about.

All the best, KH