[ger21]

Accordingto what I've read at SDP-SI, GT2's are the best choice, with the least backlash.

You want to take the speed you want to move at, and take the top rpm of your servos, and gear accordingly, so that your servos are spinning at close to their max rpm when your machine is making rapid moves. There is no general rule, like use 2:1.

Also, I see about 6-1/2 turns per inch. Maybe a 4mm pitch? You can fine tune it with the software once evreything is up and running.

[JavaDog]

Accordingto what I've read at SDP-SI, GT2's are the best choice, with the least backlash.

Ok, so GT2 belts it is.

Going with the 3mm GT system (largest in the list, no GT2 listed) - I get this:



I changed the Belt Grooves to get the Actual center distance as close as possible to my Desired - I'm guessing this is why you can change that value!

I also see now that you can change the Pulley Grooves to maintain the ratio you desire...

You want to take the speed you want to move at, and take the top rpm of your servos, and gear accordingly, so that your servos are spinning at close to their max rpm when your machine is making rapid moves. There is no general rule, like use 2:1.

Ok, so on the servo spec-sheet it says that the rated speed is 2150rpm. But, on the chart/graph - well I honestly can't figure out what speed is ideal. Looks to me like around 700rpm? But, if I am reading the chart right - 700rpm would be 85oz/in? That seems really really low...

Also, I see about 6-1/2 turns per inch. Maybe a 4mm pitch? You can fine tune it with the software once evreything is up and running.

On the X and Y Ballscrews, right? Yes, they are 4mm pitch. I'm not sure of the pitch on the Z-Axis ballscrew.

But, you saying I can work all that out in software - just gear them all the same (same pulley-pitch, belts, etc)?

[Ken_Shea]

JavaDog,
I do not see any mention of the encoder pulse used or the drive, it has been my (confused) understanding that all these components need to be optimized to one another including the controller, I presume it is Machx.
These include
1) Encoder Pulses
2) Servo no-load rpm
3) Drives (mine operate in quadrature(what ever that means, in my case it equates to 2000 pulses per second with 500 count encoders)
4) Screw TPI
5) Controller PPS capability, my reading finds that 25K in the MACH3 is best.

Also, that optimally you would design around using 80% of the servos no-load speed.

As ger21 pointed out, gear ratios should not be arbitrarily chosen, but selected with the total system in mind.

confusing, huh

Ken

[Al_The_Man]

Although many do not go through the mathematics of designing a system, it is however usefull to get an idea of the demands placed on the machine in order to at least get a feel for what the outcome will be.
The highest demand on the servo is when the motor accelerates or decelerates and the amplifier has to inject a high degree of energy in to the motor due to the Inertia of the load. And the current practice is to keep at least an inertia ratio of motor to load below 10:1
The advantage of reduction is the inertia is reduced by the square of the reduction.
This is a PDF that may at least give an idea of how a system is designed, even if you don't bother with the math portion.

3) Drives (mine operate in quadrature(what ever that means, in my case it equates to 2000 pulses per second with 500 count encoders)

This term is a bit mis-used as an incremental encoder is a quadrature encoder, even before you take it out of the box.
It refers to the phase difference between the pulses and not the count etc.
If you use the basic 500 counts, it is still a quadrature encoder.
If you multiply the pulses by four, then it is quadrature x4.
I can understand the confusion, as I have seen at least one web site that states the wrong definition.
Al.

[Ken_Shea]

Al,
So then it is not the drive but the encoder that operates in quadrature ?

Differential encoder the same ?

The highest demand on the servo is when the motor accelerates or decelerates
Is this the reason for the suggested 80% operating rpm.


Thanks
Ken