These types of errors aren't usually caused by the cutter being too low when doing X/Y rapid moves, it's most likely a rapid Z move down to the part or the simulation is being run out of sequence with the actual machining order.
Lets look at the last problem first. If a part has two operations done on it: Roughing + Finishing, and in Simulation mode I just simulate the Finish operation, there will most likely be a 'Contact with model on rapid feed' error, this is because the Simulator is checking the workpiece model as well as the 'Part' model, and because the roughing operation hasn't been simulated first, the complete workpiece is still there when the finish tool rapids down to start it's work.
If the warnings are occuring when the tool is doing a rapid move down to the part, then it's usually because the 'Safe distance' value (Toolpath) is too small, usually thsi occurs with a spherical or Torus cutter.
A good 'rule of thumb' to avoid these errors is to allow at least the radius on the end of the tool + your safe allowance.
For example (metric), if I am using a 10mm ball nose cutter, I would always allow 6mm as my 'Safe distance' value. This is 5mm (nose radius) + safety distance (1mm).
The reason for this is that a ball nose cutter can cut on it's end OR it's side.
You could also use a 'Safe level' (absolute) value instead to avoid these problems, but this is at the expense of the cutter always feeding down from this Z height which leads to a longer machining time.
You can easily find out where any theoretical collision is occuring by pressing the '!' stop on collision icon in sumlaor mode.
We can also 'optimise the feed' after simulation.............but that's a bit too advanced for now...........
Dave  |