Quote Originally Posted by Muzzer View Post
Not sure that trying to set constant velocity within the controller is the only or best way to do this. Modern toolpaths and post processors can achieve complete control over speeds and (more importantly) accelerations, as well as include smoothing functions either within the post processor or the controller itself, if that is best.

Not sure how you create your toolpaths but the likes of Fusion 360 are very much up to date and there is the added benefit of an active and responsive forum where you could ask about this in the CAM area.
When I ran my first programme using UCCNC I had it set to Exact Stop and it took about 5 hours to finish compared to less than an hour when I was using Mach3. I found out the reason was with so many tiny movements there wasn't the time for the machine to accelerate. Looking back at my Mach3 settings I found it was set to constant velocity.

From my understanding constant velocity reads ahead and optimises the toolpath to try and achieve the set feedrate but in doing so it changes the toolpath, the allowable deviation in the toolpath is controlled by the CV settings. According to the UCCNC manual: There is always a trade off between machining speed and precision. The higher the allowed machining errors are set the faster the job will be finished, because the motion planner has more space for optimising the motion, however the less the workpiece precision might be. The only way to force UCCNC to follow the exact path is to either use Exact Stop mode (which is unacceptable due to the slow feedrates achieved) or set the CV allowable deviations as close as possible to zero.

As I was happy (in my ignorance) with the work produced by Mach3 I was looking for the CV settings to use in UCCNC to give a comparable product.