Acceleration

[Photon]

Is there a way to calculate the maximum acceleration for steppers in a small DIY machine?
Is it only trial and error? If so, what would be a good starting point and progress strategy?

[Photon]

I see that there are no replies, so I'm guessing I didn't phrase my question very well.
I'll try again.
1. I want the machine to finish its work as quickly as possible.
2. The maximum speed it will move at is dictated by the material being cut, among other parameters.

The question is how to calculate an optimal (or close) acceleration or ramp up profile for the motor. I did some reading and understand that one thing that needs to be measured is the resonance frequency. Does any one have any experience with that?

How do people with working machines set their software?

[Al_The_Man]

One thing that helps in this area is to obtain one of the free system tuning software programs to calculate the inertia ratio of motor to load which should be kept below 10:1 ratio. In other words if you already have a system in place, you can use one of these programs to calculate the max acceleration you can use to keep it under this figure. Ideally you figure out these parameters ahead of time in order to calculate the motor sizing/gear ratio required.
This is all part of designing a system from scratch. If you do a search in the CNC zone you will find mention of the effect of how gearing affect the inertia ratio.
Al

[balsaman]

Acceleration is not just a function of the motors, but of the mass it needs to accelerate as well. Since every machine is different, it is indeed a matter of trial and error for the most part.

Eric

[ger21]

Originally posted by Photon

How do people with working machines set their software? [/B]

With steppers, most people gradually increase their acceleration rates, testing each time, until they start to lose steps. Then they back off the acceleration a "safe" amount. I've heard 20% used as this "safe" value.

[Photon]

Since there is no feedback in the system, how do you know when you lose steps?