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General Mach Discussion / Re: Motors / DRO not moving to issued pos
« on: August 09, 2019, 04:47:25 PM »
Hi,
CV, or constant velocity mode is the normal operating mode for CNC mills. The software tries to keep the machine moving as fast
as possible.
When it comes to a right angle corner for instance it will slow as it approaches the corner in preparation to stop exactly
at the corner. In CV mode however it will not stop but take a shortcut and round the corner slightly before accelerating
away from the corner at 900 to its approach.
You can stop the corner rounding by going to 'Exact Stop' mode, which exactly as described would stop at the corner before moving
away in the new direction. This tends to result in the machine jerking around and long cycle times. For this reason CV mode is
preferred.
There are a number of settings that can be made to CV mode that will allow somewhat closer toolpath following but the
single most important measure is machine acceleration.
If a machine is to cut a right angle corner accurately and quickly it will need to decelerate quickly and the accelerate quickly
away in the new direction. Thus you are encouraged to build and tune your machine to exhibit the highest acceleration your motors
and machine construction can attain without flexing.
Acceleration is probably more important than maximum axis velocity with respect to cycle times and is certainly more important
to tool path following.
Craig
CV, or constant velocity mode is the normal operating mode for CNC mills. The software tries to keep the machine moving as fast
as possible.
When it comes to a right angle corner for instance it will slow as it approaches the corner in preparation to stop exactly
at the corner. In CV mode however it will not stop but take a shortcut and round the corner slightly before accelerating
away from the corner at 900 to its approach.
You can stop the corner rounding by going to 'Exact Stop' mode, which exactly as described would stop at the corner before moving
away in the new direction. This tends to result in the machine jerking around and long cycle times. For this reason CV mode is
preferred.
There are a number of settings that can be made to CV mode that will allow somewhat closer toolpath following but the
single most important measure is machine acceleration.
If a machine is to cut a right angle corner accurately and quickly it will need to decelerate quickly and the accelerate quickly
away in the new direction. Thus you are encouraged to build and tune your machine to exhibit the highest acceleration your motors
and machine construction can attain without flexing.
Acceleration is probably more important than maximum axis velocity with respect to cycle times and is certainly more important
to tool path following.
Craig