# Stepper motors - stride angle?

I am interested in using one of these cheap stepper motors for one of my projects, but need a step angle of ~2°. I came across the 28BYJ-48 and noticed that it has a "stride angle" of 5.625°/64. What exactly does this mean? I doubt it will give me the 2° accuracy which I desire, so maybe I could use a gear system to reduce that step angle further.

But in general, what is that stride angle referring to?

• The manufacturer's data sheet refers to "step angle". – Leon Heller Mar 14 '13 at 18:35
• The Kiatronics page is clearly produced by someone who speaks English as a second language, who worked from a translated data sheet (English to Chinese or Japanese, I'd guess) and then translated the translation of step as "stride", which is not an unreasonable mistake. It's like the story of the translating program which took "Out of sight, out of mind", translated it into Russian and then translated the Russian to English, and got "Invisible idiot". – WhatRoughBeast Mar 7 '16 at 21:34

5.625 = 360 / 64, ie, there are 64 steps per revolution.

However, the actual number of steps can be some multiple of that, depending on how you energize the windings. 2 to 4 times that number is easily achieved, and microstepping drivers can provide substantially finer interpolated resolution.

Your specification is not very clear - you seem to say both 2 degree steps, and 2 degree accuracy. Probably you want 2 degree steps with an accuracy of some fraction of that.

64 steps is relatively course - 200 step motors are widely available.

If you are looking at mechanical reduction, consider toothed timing belts and sprockets instead of gears. They are have less critical needs for mechanical alignment, and run quieter. If your system must operate in both directions without slop, the fact that timing belts suffer minimal backlash when the direction of torque is reversed makes them strongly preferable versus gears.

The notation 5.625°/64 indicates that the motor has a step angle of 5.625°, and the output shaft is driven via a 64:1 gear ratio. If you look at the picture of the motor, you can see that that output shaft is offset from the center of the unit, also indicating a geared output shaft.

So, following through, the motor has 360/5.625 = 64 steps/rev, but the output shaft has 64 steps/rev * 64 gear ratio = 4096 steps/rev, or 0.088°/step

That should be plenty of precision for you!

Two easy solutions:

• Most stepper drive IC's will support 1/2, 1/4, 1/8th or 1/16th micro-stepping, so you can divide the number by that to get much better resolution.
• Use gearing / belts
• Do you have any recommendations for stepper driver ICs which can do this? Thank you. – capcom Mar 16 '13 at 2:23
• Not really, we use A4988's but these are not DIY mountable without a hot-plate and a heat gun. Microstepping is a common feature though, googling for stepper driver IC's should turn up plenty. Allegro should have something. – John U Mar 18 '13 at 9:09
• Ya, but the A4988s are a little expensive, at least as they are on breakout boards because they are too small to DIY. I know they are used with RepRaps. – capcom Mar 18 '13 at 14:58
• I never promised cheap. The 4988's are cheap compared to the ones which are serially-driven and you just tell it where to go and it does the full motion control routine for you... – John U Mar 18 '13 at 17:31

I have never seen 64 steps per revolution before - the two common step angles are 7.5 degrees (48 steps/revolution) and 1.8 degrees (200 steps/revolution) but 5.625 * 64 = 360 degrees, so "stride angle" must just be the maker's term for step angle.

You are probably better off with 1.8 degrees (200 steps/revolution) but you could use this motor if you had to, half stepping would get you down to 2.8 degrees/step.

• This particular motor, the 28BYJ-48, is perhaps the cheapest stepper motor available on eBay ($2 to$3 with free shipping), and thereby has become a popular buy for hobbyists on a budget. I have a couple of them somewhere in my collection as well. – Anindo Ghosh Mar 14 '13 at 18:13
• Good to know. Most of my steppers are cheaper though : out of old Epson inkjets! – Brian Drummond Mar 14 '13 at 19:24

Actually after experimenting on this stepper motor with different Steps and speeds i found that it moves 2048 steps/rev with a max speed about 13 rpm so that means it is actually geared with a 32:1 gear ratio since 64(steps/rev)*32=2048 steps/rev.hope this helps :D

stride angle means the the degrees per one step but in half step mode not the full step one, and since the gear ration is 64 so the final number of steps per rotation in full step mode is 2048 step and in half step mode is 4096.

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