The majority of CAD CAM programs do NOT produce curves and arcs, but actually produce a vast number of short straight lines to produce the arc. You can see why, because looking at an arc, unless it was reqular shape to which there is a mathmatical formula (e.g. a circle, or elipse etc.) it would be impossible to mathematically predict where the curve would go next.
GCode requires a seperate line for each of these short straight lines.
If you have your machine on Exact Stop (Config/General Config - 2nd Column), then the machine does that - all axis stop after each line - which accurately produces the shape written. It does however produce what appears to be jerky movement - since some of the lines will only be millimetres, or fractions of an inch long.
If you downgrade the resolution, the CAM produces fewer lines, resulting in fewer stops, producing less jerky movement.
You can change your machine to Constant Velocity and here, Mach 3 calculates the next line, and, as it is slowing at the end of the prrevious line, it also accelerates into the next line, so the machine does not stop.
The disadvantage (or advantage of this) is that it also smooths out corners - i,e, the points disapear - so if describing an arc it can actually help to produce a smoother curve. Because the machine does not stop, it is less jerky.
If you are, however, in the same program also cutting sharp corners, you need to change back to exact stop to do so, since constant velocity rounds corners, whether cutting inside or outside the shape.
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