Config Setup

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    Hello All,

    I have been reading up on the this and robs sand table project for some time and have decided to build a table myself. I have built the 100mm arm version with A4988 drivers and 1/16 stepping, the micro is the Esp 32 Huzzah dev board. I have discreetly wired the steppers to the esp and have confirmed that both motors are being controlled. As of now I am using the SandTableScaraPiHat2 config. The two issues/questions i have right now is about the config. Right now the enable pin (pin 4) does not appear to be going low and activating the motors. If I force the enable pin low all the time the steppers are driven using the web UI. Is there something wrong with pin 4 in the config? My other question is how many steps per rotation should I set? the default states 9600 but I figured that with 200 steps per rotation and 1/16 stepping i should put 3200. This results in an odd motion that does not seem to match the distances it says it should be going.

    Curious what other people did.

    hope to hear back, this project is awesome 🙂


    Try using SandTableScaraMatt. The pi hat is for a Raspberry pi.


    Hi All,

    So, I believe this falls under the Config section as I’m having challenges with drawing patterns and .the files….

    I tried to create a board explaining my challenges with links directing to Dropbox but I keep on getting the “This topic is pending moderations” after posting…. and after some while… “This Page doesn’t exist” … which is Weird….

    So, third try without any links….

    The sand table is finally up and running and drawing some patterns… well…. weird patterns…. The lines doesn’t conform to any possible shape applicable to the corresponding pattern being drawn (random zig-zag lines when a circle is expected).

    I tried numerous patterns downloaded from the web (the files) however, it seems that the program is reading the code wrong?

    The pattern it draws is random lines that don’t make sense… No neat or formal pattern at all…

    The ONLY pattern I could find that is working on the table is only ONE of the Spiral patterns on the Juggers website called “Spiral 4”

    This proves that the bot can read a pattern.

    Does anyone else experience the same issue? Or, does anyone have a pattern I could try that they know is working on their setup? My email address is

    I have uploaded all of the patterns I have multiple patterns loaded onto a dropbox folder which I would like to share with the group for testing but it seems that the dropbox links posted on the thread cause hiccups…

    Here is a manual paste of the link to the dropbox folder:

    Please really looking for assistance here.

    Kind Regards


    Your steppers might be wired to the wrong motor drivers since the upper and lower arms are driven at different angles to control the motion of the arm. Having them flipped might explain the nonsensical movement.


    So I actually just solved a very similar problem to what you are describing. Turns out I needed to swap the motor polarity on one motor and leave the other untouched. This means moving the pin connected to A1 and swapping it with A2 and the same for coil B. I just tried several combinations of swapping polarity and changing the motor between steppers until the pattern I was running looked right.


    Good evening dfronek,

    Thank you for the prompt response. It is appreciated.

    I’m not sure I’m following your last recommendation… Are you referring to the Drive M1A and M1B ports (referring to the electrical diagram shown on the DIY Kinetic Art table form of MattG) to be swopped?

    So, I have tried to swop the wire terminals at the drive ports M1A and M1B as well as M2A and M2B but it seems like it is not working.

    At the moment I can only draw 1 partial pattern and that is the pattern by Juggers website called “Spiral 4”. It starts with the spiral and is drawing it really nicely, but as soon as it comes to the end it buggers up the whole pattern.

    With other patterns, it doesn’t even remotely resemble the patterns when it draws. I’m struggling to upload photos to this form as when I use dropbox links the form doesn’t want to post it…

    Will it be possible (if you are willing) to send me a mail to my pvt email address so that I can share photos of what my bot is currently drawing and maybe share a pattern you have that works to see if my bot can draw the same pattern?

    Kind Regards


    Sorry for the confusion Hendrik, referring to the schematic I simply flipped the header 180 degrees, so the pin connected to M1B is now connected to M2B, and the pin connected to M1A is now connected to M2A. This just inverts the direction one of the steppers is going. This combined with trial and error of swapping what motor each stepper driver was controlling solved my issue. Also depending on what version of the arm you are using they may have different lengths from what is in the configuration file. This can be changed by altering the config option “maxval” to reflect the upper and lower arm length in mm. There are two maxval config options, one for the upper and one for the lower arm. It appears that you are using the TMC2100 stepper drivers and I assume you have not used the jumpers on the board to change the drive configuration. changing these jumpers will alter the steps per rotation configuration and could also impact your arms’ movement.

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