Brass laps also are very popular for lapping ribs. While not quite as rigid as steel laps, brass laps are easier to work to thickness and shape and they don’t suffer nearly as much from the deep, zigzag scoring as steel laps do.

Overall, brass laps may be the most finish control-orientated lap being used. The downside is the large grains of diamond and lapping compound are still shattering from the pressure and cutting action of the profiler, which results in slower times to finish.

Copper Laps
Although copper laps are hardly ever used, they are extremely valuable to the polisher. Their use offers a great improvement in time saved while polishing ribs. This is due to the softness of the copper itself. Copper laps are so soft that the rough grain of diamond or lapping compound never breaks into fine particles. Instead, the large particles embed themselves into the soft copper and become a truly aggressive cutting tool – causing more wear to the EDM than any other form of lap.

Unfortunately, copper is so soft that dressing it down thinly enough for most ribs takes all of the strength out of the lap itself – making it practically useless except for the widest and shallowest of ribs. Whenever possible, copper laps should be used as a great timesaver.