Re: Rong Fu RF 45 vs RF 31 CNC - Help!

As the project leader of a SIG of the Valley Metal Group, which
converted three (3) RF-31's to CNC with Servo Motors, I can tell you
that any of the machines made on this model are convertable. We had
ENCO, GRIZZLY and an Actual Rong Fu. They were all compatable.

We chose to build with Servos and GECKO drives. We are getting
feedrates of 60 inches per minute and rapid feeds of over 120 inches
per minute.

Our plan was to maintain the overall footprint of the machine and we
made a maximum effort to compact this conversion. The Z AXIS servos
system is concealed inside the head, and driving the spindle
directly. I found that using the Rack and pinion supplied as
standard with the RF-31 you could not get accuracies of +/-0.010"
due to the rough mACHINING OF THE RACK AND PINION.

The servos we used are ELECTROCRAFT and they draw about 6 amps
each. We used commercial ballscrews and nuts from ROCKWELL and the
ball screws specifications are accuracy of +/-0.004" per foot. When
I measured these ball screws the numbers were less than 0.002"/foot.

We made our own ZERO BACKLASH ball nuts using two ball screw nuts,
two adapters and a spring. The ballscrew nuts cost $27.00 each and
if you purchase a zerobacklash ball screw it will cost $127.00.

I have extra parts from this conversion group and i will be selling
them since one of the members of the group dropped out of the plan
and we had made parts for the fourth unit.

Everyone thinking of this conversion should look at MACH2 for
software as it is better than anything available. This software is
true to the ANSI standards, and is equal to the FANUC/GENERAL
NUMERIC controls which cost over $15,000.