[dangercraft]

Hello everyone,
I am working on my home VMC and I have a quick question...

First some background:

The machine is a Tree VMC 1060 (about 1994), travels are 40x24x25. I got this machine for next to free a couple years back, as it had some problems. After completing some other projects I am getting started on this one...

I am swapping out the Delta Dynapath control for LinuxCNC and I am thinking about switching out the servos as well. The servos are MSI, model 165-SFP-13B, resolver type units and I can't seem to find any information on them, the amps or the manufacturer (The VMS manuals don't say either.) For several reasons, my inclination is to swap them out for used, modern AC servos from Ebay. Here-in lies the problem. I have no idea what the specs are on these (the plates don't say), other than that I can figure that the RPM's on the motor are only about 300 (?!?). I figured this out because the rapids on this machine is 700IPM, the ball screws 2.5 inch pitch and there is no reduction between the motors and the screws which are belt driven.

My question(s):
Anyone happen to have any info on these servos?

Better yet: In a modern-ish heavy duty machine (mori, mazak, etc.) of the same travels and capacity, what size motors are normally spec'd? Gear reductions? Ball-screw pitch?

What I would like to do is install modern, used AC servos so that after I reduce to match the rpms and the ballscrews the torque applied to the balls crew is the same or better as what I have now.
I'd like to size the new motors so that I am getting a comparable amount of power to the table as the stock machine (which I understand was pretty powerful) or better yet, something comparable to a modern heavy duty VMC. For the reduction, I figured I would make a double reduction belt drive, say 1:3.33 + 1:3 for a 3,000 RPM servo.

Thanks!
Frank

[RICHARD ZASTROW]

2.5" pitch ballscrews????????? Might want to re-check that one.

Dick Z

[dangercraft]

DOH, you're right, I screwed up.

What I meant was 2.5 turns per inch.

According to the manual, the rapids on this machine are 790 IPM. So thats: (790 IPM / 2.5 IPR) = 316 RPM.

That sounds right?

Sorry about that.

Frank

[dangercraft]

Ok, found out the machine came with 200 in pound servos, thats about 22.59nm. To to figure out what to do.

Dangercraft

[bhurts]

Is that continuous or peak rating?

Ben

[dangercraft]

According to the manual, continuous. Those things are enormous.

Frank

[Larken]

DOH, you're right, I screwed up.

What I meant was 2.5 turns per inch.

According to the manual, the rapids on this machine are 790 IPM. So thats: (790 IPM / 2.5 IPR) = 316 RPM.
That sounds right?

No, that too slow.

790 in/min = 13.1 inches per second (790/60)
at 2.5 turns per inch it would need 32.9 turns per second ( 13.1 * 2.5 )
rpm =32.9 x 60 = 1974 rpm

[dangercraft]

You're right, I should have multiplied by 2.5, not divided. Don't know what I was thinking about.


Thanks!
Frank