as anybody ever tried roller pinion like those (http://www.nexengroup.com/rp/?gclid=CILYotDs5owCFRaSQAodwURE0Q)to retrofit
how do they compare to ball screw

i was looking at thoes back when i was working on my cnc router.. and it just turned out to be a cost thing for me... if you have a large distance to cover, and need accuracy over that distance, then it might be an option, but i really cant see the advantage to useing it on a mill.. infact i can only see drawbacks to this vs ballscrews.. one, it would require a complete redesign, 2 its gonna take some healthy gearing and or some pretty torque-y motors... 3 i would think that chips would build up in the gear rack and cause problems...

just my thoughts tho.. never tried it, so i cant say with any cert..

looking at the pdfs you'd still need a rail system to get any precision "cross-axis" I was hoping that you'd be able to elminate rails when Iyou showed the linkl. Nope! Pinion slot runs 3 - 5 mm wider than the rack. Bummer - BUT very high resolution along the axis.

Nice thinking outta the box!

:cheers: Jim

Actually, looking at that setup it might make for a really good starting point for a remotely mounted automatic tool changer. It can be mounted to the side and have an X and Y axis of it's own. You could have rows of tools Mounted on a table, which would slide over the work piece after the Z axis is topped out to allow for(hopefully)enough room to slide to tools into place. The table would slide in to the desired tool position to drop off the existing tool then to the new position to pick the next tool up. The sliding table would need to be made from light weight material to prevent tipping of the table as it extends beyond it's supports. It could also be mounted to the front of the machine utilizing the shorter Y axis distance to limit the amount of distance it must travel beyond it's supports. Or am I unwittingly pirating someone else's idea?

Interesting thought - just took a look at some of the application data - several things to consider - the smallest system is 3.2" from the bottom of the rack to the top of the roller - could be mounted with the rack on top to minimize chip collection - ~ 6" of travel per revolution so to resolve, for example, 0.0001" with a 200 step/rev motor, the gear reduction would be around 300:1 probably beyond a reasonable range for a single reduction stage and then there is the question of how much backlash the gear train would introduce to the system. I haven't done a back calculation to see how the maximum linear forces compare to the typical torque X reduction numbers from conventional screw drives.

For me it is interesting but a moot point - having lurked on this forum for several months, I have decided that the best route for my application is a ready-to-go Taig set-up - just waiting to accumulate the funding!

EM

Does anyone have the cost on this.

Might be a nice alternative on a cnc router. Or a Bridge mill.

as i remember it was about double the cost of just regular rack and pinion parts.. but dont hold me to that...