Stepper Motor woes
 
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Stepper Motor woes

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Inq
 Inq
(@inq)
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Joined: 10 months ago
Posts: 982
 

@christine86 - I notice that you have not marked this Solved and I have not read the full topic, so apologies if I'm just repeating something someone else has already suggested.  

Having just worked through a problem with an A4988 https://forum.dronebotworkshop.com/motors/mal-justed-a4988 and reading your O.P. I recognized some of the behavior your mentioned.  

  1. Getting the the current setting high enough is the first challenge.  I could not get mine to register anything higher than 1.02 amps.  I was shooting for 1.5 also.
  2. But mainly I recognized the chatter as being where it "skips" a step.

As I'm sure you know, "skip a step" is jargon from 3D printing... but basically when the available torque (from supplied current) is not high enough to move to the next step, it pops back to the same step... basically ignoring the command to step.  I noticed the "chattering" you described when I used my fingers to retard the shaft... thus skipping steps.  

Even if you get this working on the test bed, I suspect that once you start loading it up with hardware, you'll experience the problem again.  The torque required to overcome the startup inertia of that heavy of a platter will be quite high.  

You seem to be quite adept as using CAD/3D Printing... Have you  considered creating or just downloading some reduction gears from Thingiverse... if you use enough reduction, you can turn a freight train on your turntable.  😉 🤣 😎 

VBR,

Inq

3 lines of code = InqPortal = Complete IoT, App, Web Server w/ GUI Admin Client, Access Point Manager, Drag & Drop File Manager, OTA, Performance Metrics, Web Socket Comms, Easy App API, All running on ESP8266...
Even usable on ESP-01S - Quickest Start Guide


   
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Christine86
(@christine86)
Trusted Member
Joined: 3 years ago
Posts: 43
Topic starter  

Hi @inq,

My bad, I didn't realize I had to mark this as solved!

It is solved now, though everything you mentioned WAS a problem. I had to go to 800 steps per revolution, & accelerate it from rest VERY slowly. I didn't realize just how heavy all of my parts are, especially the 16 trillion hex-head bolts & nuts I've collected. This is a picture of the finished project. I listed it some time ago, on thingiverse. It's now another project that no one will ever build. 🙂

Carousel

The link is https://www.thingiverse.com/thing:5343593  

I think of your thoughts on reduction gears, & am reminded of Archimedes purportedly saying "Give me a large enough lever and I'll move the world!" It's all about mechanical amplification.

Thanks for writing, as i said, I did suffer ALL of those problems, & found the only work around was to barely move the stepper, it takes 45 degrees or so before I get to the full speed I dare try to move it. And that's NOT very fast!

thanks,

Christine


   
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Inq
 Inq
(@inq)
Noble Member
Joined: 10 months ago
Posts: 982
 
Posted by: @christine86

My bad, I didn't realize I had to mark this as solved!

Nah!  You don't have to.  There is no forum Nazi. 😉  I just found the feature the other day and have started using it when I ask a question and someone solves it.  As you might have noticed, on some threads, they may go through many pages as people like to go off on tangents about whales, trees... beans in China.  It just lets someone know right off the bat that it's been solved.  If they came to it to help... they can see, it's not needed.  If they came to get help with the same thing... it lets them know somewhere is a fix.

image

I looked over your Thingiverse link.  Way cool project.  Say... worse case having to move through 180 degrees.  How long does it take?

VBR,

Inq

3 lines of code = InqPortal = Complete IoT, App, Web Server w/ GUI Admin Client, Access Point Manager, Drag & Drop File Manager, OTA, Performance Metrics, Web Socket Comms, Easy App API, All running on ESP8266...
Even usable on ESP-01S - Quickest Start Guide


   
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Christine86
(@christine86)
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Joined: 3 years ago
Posts: 43
Topic starter  

@inq Thnx for that, I learnt two things today,

1/ I learnt that if you had your adblocker on, you can't find the solved check box, &

2/ It takes 11.6 seconds for the carousel to move 180 degrees. Which is slow, but not as slow I had thought it was.

Cheers,

Christine


   
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