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Topic: Geared Stepper Motor (Read 12 times) previous topic - next topic


According to Stolfa the motor requires 64*((22*26*31*32)/(9*9*10*11)) steps for a full revolution. This fraction simplifies to 1650688/405. Therefore 405 turns are needed to get back to the initial starting position.


Having played around with this stepper for a couple of days, my results show an inconsistent undershoot similar to the previous posts.
Maybe this could be a power supply problem ?
Perhaps any future posters could post the type of supply they are feeding ULN2003.
For my part, I was using 2 paralelled 9V (PP3) batteries.


For high-precision geared motors anti-backlash gears are normally used (where spring-loaded gears remove all
the slack in the mechanism).

Adding a hi-res shaft-encoder after the gearbox would allow accurate positioning without needing to worry about
slack or the precise gear ratios...
[ I won't respond to messages, use the forum please ]


   I just received a new 10-pk of these 28BYJ-48 5VDC stepper motors and tested one to see if maybe a different manufacturer would use a slightly different gear ratio, some being 4096:1 and some being 4075.7728...   I set the stepper motor sketch up so that it rotates for 4076 steps, pauses for 3 seconds, then repeats; a period of about 15.3 seconds.  Depending on which ratio is in the gear box it either exceeds a revolution by 0.22271 steps or it is short a revolution by 20.2271... steps.  If the gear ratio is 74075.7728.. the paused point of the shaft will precess one revolution in 79 hours.  If the gear ratio is 4096:1 then the pause should precess in the other direction and make one revolution in 51 minutes.  Right now it's on course for about a 79 hour precession.  There may be another source of these motors with a 4096:1 ratio. If you know of one; let me know.



I can't believe there are so many motors that are not 4096:1.  Why? 
Does anyone else have the 4096 ratio?
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