Its common on conveyor lifters to add a counterweight to reduce the effective mass that is lifted and hence reduce the work done by the motor. Its also common on fork lift trucks. I believe the mass is set to around half the maximum lift weight or half the expected mass to be lifted in the case of a conveyor.
The mass is connected so it hangs the other side of the top roller and assists the lift by effectively counteracting the mass.
Speaking simply and ignoring friction I think you are all partially correct.
If I remember my physics right, the counterweight would naturally accelerate down at 9.81m/secsq (gravity) if unconstrained, so I think it assists acceleration up to that value when the carriage is rising and the counterweight is moving down (above that acceleration value the connecting cable is basically unloaded) so you don't get any benefit.
When the main carriage is moving down and the counterweight is moving up, The counterweight resists the acceleration as the masses are effectively combined..
I could understand there may be a benefit if the carriage is many kilograms, but for a light carriage such as on the delta, the frictional forces are probably the main ones you are concerned with. This counterweight system would be more complex so any benefits you might gain would be hidden by the increased friction of the more complex mechanism.
Viktor does raise an interesting point as there may be some benefit to reducing the Mass of the tool head by connecting it directly to a counterweight or spring. I think you would only see a benefit when moving up in the Z direction quickly. As a 3D printer only does this in small increments every now and again, the benefits would be minimal with current printers.
Its a good suggestion though and one that could be effective on larger machines such as those that they are considering to print buildings.
The mass is connected so it hangs the other side of the top roller and assists the lift by effectively counteracting the mass.
Speaking simply and ignoring friction I think you are all partially correct.
If I remember my physics right, the counterweight would naturally accelerate down at 9.81m/secsq (gravity) if unconstrained, so I think it assists acceleration up to that value when the carriage is rising and the counterweight is moving down (above that acceleration value the connecting cable is basically unloaded) so you don't get any benefit.
When the main carriage is moving down and the counterweight is moving up, The counterweight resists the acceleration as the masses are effectively combined..
I could understand there may be a benefit if the carriage is many kilograms, but for a light carriage such as on the delta, the frictional forces are probably the main ones you are concerned with. This counterweight system would be more complex so any benefits you might gain would be hidden by the increased friction of the more complex mechanism.
Viktor does raise an interesting point as there may be some benefit to reducing the Mass of the tool head by connecting it directly to a counterweight or spring. I think you would only see a benefit when moving up in the Z direction quickly. As a 3D printer only does this in small increments every now and again, the benefits would be minimal with current printers.
Its a good suggestion though and one that could be effective on larger machines such as those that they are considering to print buildings.
