Mach Questions

[tsutt]

What is a standard mach controlled mill setup? As in I have servo's that have encoders, Will these work 29in lbs 140v. 6.8 amp. What else is needed,like servo drives ect. this would be on a knee mill. I know this is vauge, but it's a place to start. Todd

[ger21]

You need drives that can accept step and direction. Rutex makes some that can handle the voltage you need. www.rutex.com
Also, if you have high res encoders, they may limit your top speed, as Mach3 has a max of 45000 steps per second.

[WayneHill]

Is the max limit of 45000 sps due to the Windows interface? Or will a faster computer have a higher steps per second?

[Bloy2004]

nope... the 45khz is limited by windows. A faster computer doesn't affect the pulse rate, but it DOES help in handling the processes.

I have 180VDC motors with gecko 320s at running at 73VDC ... I'd like to have Rutex drives to get more speed out the motors, but there is enough speed on a rack&pinion dual axis router. The encoders are 500cpr(2000ppr) and am with 75khz setup...
I plan to replace the 500 encoders with 250ssometime in the future, but for now I am happy with the 500 encoders.

[tsutt]

So what does this mean as far as speed goes with 2000ppr encoders and 2-1 belt reduction. Todd

[Bloy2004]

There are other considerations.... your drive screw pitch, speed of motors under usable voltage, etc.
Here is how I figured my needs, and why I would have more "comfortZone" with 250(1000) encoders:
http://www.cnczone.com/forums/showpo...5&postcount=14 ( I can't edit this anymore but where it says Mach's max ppr is 45,000, it should say pps(pulses per second).

P.S. I do have a power supply that provides lots of amps(25A) but it isn't used most of the time... if ever. The transformer stays only warm and enables good acceleration of all axes simultaneously. I can't max out the speed, but fortunately there is plenty ...any more and the mechanics would be stressed out. With the 250 encoders on my dual motor rack & pinions, I would have faster rapids to get to the other end of the router table.....but lose resolution. If I had more $, I might have opted for the Rutex drives that handle over 100VDC.

[ger21]

Originally Posted by tsutt So what does this mean as far as speed goes with 2000ppr encoders and 2-1 belt reduction. Todd

You'll get about 3 revolutions per second.

[Bloy2004]

Hi Gerry,
How did you come up with the 3 revs/sec?

John (bloy)

[ger21]

2000 is 8000 with quadrature, geared 2:1 is 16000 steps per rev, or about 3 rev's per second, right?

[Bloy2004]

hmm.. I think the 2000ppr is already the pulses per rev....
so, at 25khz you get 12.5 revs per second..... halve that for 2 to 1 belt reduction and you get 6.25 revs per second.

Or, at 45khz, you get 22.5 revs per second....halving that and you get 11.25 revs per second.

This is figuring the ratio is a reduction....

my interpretation may be wrong...

[tsutt]

So.....if thats the case. 3rps x 60 =180rpm/ 5rpi(.2 pitchscrews)=36 ipm. That would be totaly inadequite. Todd :frown:

[ger21]

Originally Posted by Bloy2004 hmm.. I think the 2000ppr is already the pulses per rev....

Does that depend on the drives?

Edit:

I just reread a few posts, and see what you're talking about, so You're probably right.