Originally Posted by cnczoner  BTW, I contacted these folks today... Nexen. Looks awesome if it meets their claimed specs, but expensive -- $409 f/each roller pinion, and $420 for a 39" length of rack. |
Disclaimer: I represent Nexen Products in Illinois as a distributor.
With that said, the Nexen Roller Pinion System is awesome!
It has some pretty incredible properties compared to a typical rack and pinion or a higher precision ball screw with preloaded nut.
One of the limitations ball screws it that the absolute accuracy of a screw increases linearly with the length. Longer screws will have a wider accuracy band.
However, because of the way the racks are manufactured, the error in non-cumulative. Also, because there is a rolling action, the efficiency is much higher than it would normally be in a rack and pinion setup. The lubrication requirements are limited because the rack is self lubricating with the coating on the rack.
Another neat part is because 2 or 3 teeth of the roller pinion are always engaged, there is no backlash.
To top it off, the speed the Nexen RPS allows is incredible - 425 in/
sec!
If you compare this to the cost of screws with similar accuracy grades with preloaded nuts, and the fact you can't get nearly the speeds, I think it has a lot to offer. The gantry manufacturers I've worked with agree!
http://www.nexengroup.com/rps/
Matt