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What are “steps per turn”?

2012-02-22 Dan
Dear Dan,
Recently I am working on the Delta Robots. I look your forward and inverse Kinematics of the delta robots and it help me a lot.
In your application of forward and inverse kinematics there is a term “Steps per Turn” and this term in controlling the resolution.
What do you mean by this term ?
I am implementing this kinematics in MATLAB. How I can implement this “Steps per Turn” in my code or how I can calculate the resolution in my case.
Thanks
Regards,
Zeeshan
I use three NEMA17 stepper motors to control movement of my robot.  Hobby servos have 256 positions in 180 degrees.  My steppers have 3200 steps per turn. I calculate resolution as distance tip moves when servo makes one step.  Better would be to calculate all steps at all positions and find max/min but this is javascript and it would probably kill your browser.  I have some code in the open source project that calculates the exact shape of the envelope.  It could easily be expanded to calculate the min/max step (which might not be the same size everywhere in the envelope).
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Drawing Lines, Arcs, and Halftones with a Wall Hanging Arduino Drawbot

2012-02-13 Dan

Download the code here

2013-11-26: updated link to github project!

Among the various features are…

  • Verbose output: Debugging line and arc drawing took a lot of work and I see no reason to remove all the helpful debugging messages.  Maybe it will give you insights to my madness.  uncomment #define VERBOSE to see the storm of messages in the serial interface.
  • Serial command interface: Type commands to the drawbot and it will execute them.  Draw all the arcs & lines you want.  Write a javascript app to send whole SVG files to your drawbot.  Don’t worry about mistakes because I’ve added
  • Sanity checking: Try to send the drawbot out of the work envelope and it will refuse with a cryptic error message.
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Building a Delta Robot: 3D printed joints

2012-02-09 Dan

The green is one half of my first attempt.  The two on the right are attempts 2 and 3.  The assembled joint in the bottom left has an M3x20 screw and a 1/8 ID, 3/8 OD bearing.  In every single case the round part that holds the bearing cracked when I inserted the bearing.  In each case I increased the size of the hole.  In the last version I tried to file the inside edge and even smooth it with a drill bit.  While 3D printing is great for proof of concept I don’t think the makerbot is up to the levels of accuracy I’m going to need from these joints.

I wonder how it would do with shaft couplers and shaft collars.  Hmm…