Tuesday, June 12, 2012

Linear motion drives for CNC router


v Ball screw (problems: backlash, not self –locking, expensive)

v Lead screws/power screws/translations screws: (efficiency 25%-70% , higher pitches result in higher efficiencies)

§  Acme screw (cheap, small/no backlash. Small pitch and slow speeds)

§  Square screw (most efficient, least friction, most difficult to machine, and most expensive)

§  Metric V thread (lowest efficiency)

v Rack and pinion
The following table shows a quick comparison between lead screw and ball screw as they are almost used in hobby CNC routers


Point of view
Lead screw
Ball screw
Efficiency
Linear speed
Slow
High
Self-locking
In most
No
Cost
Relatively cheap
Expensive
Manufacturing
Easier
Difficult
Backlash
Small
Large
Backlash compensation
Using Anti-backlash nut
Using software
Pitch
Small
Large