stepper motor : step size

Hi,


I am doing some research before building my first reprap, and i'd like to know the importance of the step of the stepper motors. If fact the real question is whether I should buy 0.9° stepper or if 1.8° are enough.


Thanks a lot

A smaller step angle gives you more resolution, or the same resolution at a lower microstepping setting, theoretically giving you more accuracy if the rest of your machine is high enough quality. Pay careful attention to belt tension and use good pulleys if you want to see any of this benefit. The trade off is that the electronics can only generate step pulses so quickly and you wont be able to drive a 400 steps/rev motor as quickly as a 200 steps/rev motor at full microstepping.

All in all, I wouldn't pay much extra for 0.9° motors, but If you can get them at a good price, go for it.

Thanks a lot for your help.

Edited 1 time(s). Last edit at 05/30/2012 07:38AM by karlito139.

Until we have ARM micros you will never be able to use all of the steps at 1/16 stepping, you would be limited to 1/8 stepping.

... for my IMS-drivers with 1/256 microstepping (51200 steps per rev. with an ordinary 1.8deg-stepper) I'm waiting some years now ... and mybe some years more, until the micros will handle stepping-clock frequenzies upt to 10 MHz

1/8 microstepping (1600 steps per rev. with 1.8deg- 3200 spr with 0.9deg-motors) should be enough for actual needs ...

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Worth taking a look at the Reprap Calculator as this will help

[calculator.josefprusa.cz] and scroll down to steps-mm belt.

Here you can quickly see the combination of things that will determine the resolution you want your machine to achieve.

1.) Motor Step Angle
2.) Stepper Driver (Micro Stepping)
3.) Belt pitch
4.) Tooth count of drive gear.

All of these can be adjusted to suit the equipment you already have, to get the best resolution you want.

If you went for 1.8 degree with say a 1/16 stepper setting, 5mm pitch belt and tooth count of 10 you would end up with 64 pulses to move your machine 1mm so your resolution would be 0.015mm

But if you went for 0.9 degree with say a 1/16 stepper setting, 5mm pitch belt and tooth count of 10 you would end up with 128 pulses to move your machine 1mm so your resolution would be 0.007mm

By changing the other values in the calculator it should help you work out your final pulse settings you need to program into your firmware as well as work out what hardware you want to purchase.

All good fun !

Cheers

Sean.

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Yeah, good luck with your arduino based micro handling 1/16th on .9deg motors. Again this is not feasible with todays micros until we have ARM micros at around 100mhz.

Tanks a lot for your help. I didn't know about this calculator, it is great.

So now the Arduino Due 32bit is out and has 85mhz We are getting closer to 100Mhz. So perhaps 0.9 degree stepper is feasible.