Hi.
Sorry for asking what to some of you would be a stupid question but when would you use a lower than maximum speed on your router?
Since the woods are pretty similar to each-other in instrument making, and the bits used are rather limited, that's not a stupid question.
In general woodworking, one wants to match the
cutting speed and the cross sectional area of the cut to suit the material, and it's properties.
In order to keep the cutting speed reasonable, the spindle speed has to be reduced. Also If you use oddly shaped bits with large diameter changes, the spindle speed may have to be adjusted.
Routing any wood that splinters easily, may benefit from a lower spindle speed as well.
When routing for deep pockets, reduced speed can aid in the control and chip removal.
Too high speed on a hard material can lead to premature dulling of the blades.
Too high speed on synthetics (plastics mainly), will melt the material.
etc.
I'm sure the more experienced woodworkers will present other needs for spindle speed control.
Edit: Oh, almost forgot,
Festo OF 900E is my choice for a router. Then again, I have a milling machine for really rough or precision stuff if the need arises, so a small plunge-base one like that is enough.
Regards
Sam