Rockwell Mill CNC conversion - Expert Opinion please

[Fraese]

Hi,

I am about to convert this type of mill to CNC for hobby metal fabrication (Al and steel).


http://s557.photobucket.com/albums/s...ent=11af_3.jpg

I located suitable ball screws and 400W Yaskawa AC Servo motors with low backlash planetary gear reducers and matching torque/speed controllers.

Using a belt drive to mount the drives, I could configure the following ratios easily:
1:1 >> 750 IPM max >> 254 lbs max linear force on table
1:2 >> 375 IPM max >> 508 lbs max linear force on table
1:5 >> 150 IPM max >> 1271 lbs max linear force on table
1:10 >> 75 IPM max >> 2542 lbs max linear force on table

Which ratio would you recommend? (My engineering degree gave me the knowledge to calculate these numbers but did not provide me with a clue how these numbers relate to real world needs. My gut feeling tells me 1:5 or 1:10 would do the trick)

BTW: I know that the knee of the Rockwell mill provides very little room for the Y axis ballnut. However, I found a second mill for cheap that I am going to subject to "knee surgery". http://s557.photobucket.com/albums/s...ent=cf20_3.jpg

TIA

Fraese