resolution accuracy

paolozampini1973

@jay_s_uk

I would like to do a theoretical calculation of the precision of an axis with nema 1.8 ° M350 = 16 4MM SCREW
external axis I want to calculate M92 = 99.975 exsternal driver and set to 400 M350 = 16 4MM SCREW I WANT TO KNOW THE PITCH AND ACCURACY CORRESPONDS
I DON'T remember how to do the calculation anymore

oliof

@paolozampini1973 https://blog.prusa3d.com/calculator_3416/#stepspermmlead

paolozampini1973

@oliof said in resolution accuracy:

@paolozampini1973 https://blog.prusa3d.com/calculator_3416/#stepspermmlead

Thank you very much that you always pay attention to me but with the link you sent me it does not help me at all

fcwilt

@paolozampini1973 said in resolution accuracy:

Thank you very much that you always pay attention to me but with the link you sent me it does not help me at all

I cannot understand what you are asking in item #2.

I'm guessing English is a second language for you.

You mention PITCH and ACCURACY. One answer is that you cannot calculate those but would get them from the manufactures specification sheet for the lead screw.

But since you mention calculating them then you must mean something else.

Frederick

alankilian

@paolozampini1973 said in resolution accuracy:

I would like to do a theoretical calculation of the precision of an axis with nema 1.8 ° M350 = 16 4MM SCREW

OK, this math is easy:

You have a 1.8 degree-per-step motor. That's 360/1.8=200 steps-per-revolution.
You are going to do 16 microsteps-per-step so you'll be doing 16*200=3,200 microsteps-per-revolution.
You have a machine that moves 4 milliMeters-per-revolution, so if you move 1/3200 revolution your machine will move 4/3200 = 0.00125mm per microstep.

Now, that's what the MATH says.

Real stepper motors do not turn 1/16th of a step for every microstep. They move something between 0 and 1/16th of a step per microstep.
WHAT??? But that means I don't gain any resolution by microstepping.
Yes, you gain noise and vibration reductions, and maybe a little resolution, but don't depend on it.

So, your system will move somewhere between 4/200=0.04mm and 3200/200= 0.00125mm per microstep.

This is the math of the system. a real system will not move precisely and accurately, so you will need to measure the actual performace of your system.

Things to lookup when learning about this:

Backlash
Axis sag
leadscrew accuracy and precision
Carrier following accuracy

There are about 100 things that affect the accuracy and precision of a mechanical system. They are all important and interesting.

I hope your needs are to be able to position something to within 0.1mm of where you want it to go. That's a reasonable target.

external axis I want to calculate M92 = 99.975 exsternal driver and set to 400 M350 = 16 4MM SCREW I WANT TO KNOW THE PITCH AND ACCURACY CORRESPONDS

I don't know what this means.