UCCNC Constant Velocity settings

[JAZZCNC]

CV is heavily influenced by acceleration and not just velocity. As the manual says it's always a trade-off between speed and accuracy so you can't have both but there are things you can do to increase it.

CV works by looking ahead and then determining the path it must take to make the corner and maintain the velocity, It does this by complex maths using velocity, acceleration, and corner angles, etc. It will also turn Off CV for a brief period for really abrupt angles which is why you can adjust the corner angle cut off point in general settings.

So the faster it can accelerate the quicker it can change direction, so with faster acceleration, it can wait longer before changing from the original path. Combine this with lowering the velocity and CV corner angle cut-off setting you can keep to the original path while still keeping a reasonable velocity.

Often you can actually lower the cycle times by lowering velocity and increasing acceleration. Esp, on work with lots of small tiny moves like 3D work.

As you have seen when you were in G61 exact stop mode you never actually reached the commanded velocity before the next move started at which point the process starts all over again because with exact stop the machine as to accelerate and then de-accelerate down again before the next move starts, this is why the whole machine shakes when in the exact stop. However, if you had turned up the acceleration then it would have cut faster as it can reach a higher velocity in less time, but the machine would have shaken more because it would be like hitting the brakes hard before the next move started.

This works exactly the same when in CV mode but it doesn't come to an exact stop at the end of each move, it just blends them into each other. However, the velocity is still lowered from the commanded velocity because it can only reach a set speed in the time before the next move comes along which it blends into it, so again the process starts all over again with the result being much lower velocity than what as been commanded.

This is why turning up acceleration and lowering velocity in motor tuning can actually lower cycle times. However it doesn't suit all types of work, so Here's a tip that I use all the time.
Setup several profiles with different motor tuning settings that suit the type of work your doing. So, for instance, I have a 3D profile where my velocity is tuned low and acceleration high. Then when doing 3D type work just load that profile.

To give you an example of the kind of time savings that can be had then create G-code for the Aztec calendar with a normal setup and simulate by cutting air, then do same again with high acceleration and see the difference in cycle time.!! . . . . You will get a shock.!

Also just in case you are not aware then you can put the machine into CV or Exact stop by typing G64 or G61 into the MDI before running the code, or by inserting it into your G-code files initialization line which is usually the first line in the code.