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grbl or tinyg ?

Discussion in 'Control Software' started by jrmussel, Mar 11, 2016.

  1. jrmussel

    jrmussel New
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    Hi guys, this looks like a lot of fun. I found grbl and tinyg after watching NYC CNC on youtube and I'm excited to get mine working. Question is to use grbl or tinyg to run 2 steppers, NEMA23 probably about 2+Amp or little better. My application is pretty straightforward so don't think I need advanced S-curve and control as in the tinyg but I do have one oddity that I'm not sure either can handle (at least without source code modification): My X,Y stage is not a straight "gantry" style where X is one axis and Y is the other axis; my X position is a function of both motors, and my Y position is a function of both motors also using some trig functions. The trig is pretty simple, should not slow down but I do need some custom function both on the forward kinematics (driving position) and the reverse kinematics (reading position).

    Which board should I use? Some basic guidance will get me rolling (er, I mean driving). I would appreciate thoughts, this looks like a blast.
     
  2. jrmussel

    jrmussel New
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    I actually mean the gSheild, not the grbl. Since only 2 axes, I think the gSheild will suffice since I don't need adavanced power like S-curves, etc. I would like some opinions.
     
  3. Sonny Jeon

    Sonny Jeon Veteran
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    Both TinyG and Grbl are cartesian CNC controllers. Or rather, assume each axis is dynamically independent of each other. Forward and inverse kinematics are not supported on either platform. (Although TinyG does have a place-marker for it, I've never seen it in use.)

    However, depending on how optimized control you need, lots of users just write a conversion script that will make Grbl behave close to what they need. For example, a two-motor CNC that controls a hanging painting head was shared a little while ago on Grbl's threads.

    Full disclosure. I'm a little biased. If I were you, I'd try out Grbl. It's a much smaller source code base and is well commented. TinyG can be very difficult to work with. It'll run on both a standard Arduino Uno or a Mega2560, if you need more flash and ram (github.com/gnea/grbl-Mega/).
     
    David the swarfer likes this.
  4. David the swarfer

    David the swarfer OpenBuilds Team
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    must put this on my Mega! it is currently running 0.9 with my custom pin assigments
     
  5. jrmussel

    jrmussel New
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    Excellent, Sonny. I as thinking along the same lines, you just confirmed it for me. I can easily do some front end math on the gcode for my own kinematics. JR

     

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