Jacob":1h0a5r0s said:
Most copiers are not that precise but the general assumption is that it shouldn't matter as you are not expected to scale (accurately) from the drawing but should refer to dimensions.
I will probably be thrown off the forum for saying this, but - Jacob is absolutely right. Every drawing that left the drawing office I worked in had a range of notes, but number 1, in big letters, was always, "If in doubt ask. Do not scale." The reason is that copiers are never quite 100% accurate, even the big, fancy expensive ones, and paper can shrink and swell a bit too.
If you want something really accurate, work to the stated dimensions, reading them from the drawing and marking them out directly on the workpiece, scaling from a good quality steel rule or similar. That, or draw it out yourself on something that won't shrink or swell during the duration of the project. Draughting film might be good option - nice to draw on in pencil, but not cheap.
If dimensions are at all critical DON'T mark out directly from the drawing.
Note - where there's a chance to fit parts to each other, and final dimensions are not absolutely critical, you can 'get away with it'. Just apply common sense to the above points.
By the way - woodworkers' rods marked out on wood tend to work because the critical dimensions are on the long grain, the movement of which is minor compared to cross-grain. MDF would probably be OK long and cross.