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acceleration
« on: November 29, 2009, 02:54:03 PM »
Hello,
Can anyone tell me if a high acceleration will reduce your accuracy. my vol is set at 300 and my acceleration is set to 5 but it is slow moving but if i set it to 30 it moves great. If I set it to 80 it slides my machine back and forth when it moves. I would like to keep it at 30 if i t doesn't hurt the accuracy.
Thanks,
Jeff

Offline Hood

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Re: acceleration
« Reply #1 on: November 29, 2009, 03:04:17 PM »
It will only affect the accuracy if your steppers loose steps when using that acceleration, best way to find out is set up some means of measuring and do a lot of back and forth  G0 moves and see if it ends in the same position it started at. You can hoever usually hear steppers when they loose steps.
Hood

Offline ger21

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Re: acceleration
« Reply #2 on: November 29, 2009, 03:05:49 PM »
If using CV mode, higher acceleration will make it more accurate.
Gerry

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Re: acceleration
« Reply #3 on: November 29, 2009, 11:02:36 PM »
Thanks,
I tried the acceleration up to 80 it didn't seem to make a difference in accuracy but it move so fast it look like it is going to tear it self appart. I left it at 30.I turned the CV mode on and I didn't notice anything I will play with it some more. Thanks for the help
Jeff
Re: acceleration
« Reply #4 on: November 29, 2009, 11:20:27 PM »
Hello,
Can anyone tell me if a high acceleration will reduce your accuracy. my vol is set at 300 and my acceleration is set to 5 but it is slow moving but if i set it to 30 it moves great. If I set it to 80 it slides my machine back and forth when it moves. I would like to keep it at 30 if i t doesn't hurt the accuracy.
Thanks,
Jeff

At some point, you'll start losing position if you go too high on acceleration.  The loss may occur on rapids, or during cutting, depending on the characteristics of your motors.  It will also make the machine shake more on starts, stops, and changes of direction.  There's really no advantage to very high acceleration, unless you're doing a lot of 3D profiling, or running at very high feed rates.  Just find a value where the response is "crisp", without excessive shaking.

Regards,
Ray L.
Regards,
Ray L.

Offline simpson36

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Re: acceleration
« Reply #5 on: December 02, 2009, 08:06:34 AM »
The effect of acceleration is not trivial.

Depending on what you mean by 'accuracy', acceleration has a huge effect if you are running high feedrates.

If by 'accuracy' you mean 'repeatability', which is actually what was discussed here, then it has little or no effect unless as has been mentioned, you push steppers too far and they start to miss steps. Missed steps are audible only if there are many in a row. One or two missed steps here and there cannot be detected by sound, but can add up to a big problem.

If by 'accuracy' you mean the machines ability to hold a tolerance, then again, acceleration cannot reduce backlash and cannot make the machine more rigid.

However, if you define 'accuracy' as how close the machine can follow a profile, then acceleration is king. High speed without corresponding high accelerations leave rounded corners and other anomalies. The effect is exactly like a race car needing to open up their line in order to make it around a tight curve.