the drawing is offbeat

Home Forum Makelangelo Polargraph Art Robot the drawing is offbeat

Viewing 24 posts - 1 through 24 (of 24 total)
  • Author
  • #20654

    Hello Dan,
    I went back to the test of makelangelo 3.2. After several tests I always get the same thing.
    The drawing is offbeat and the pencil does not return to its starting point.
    After several drawings I change in the parameters of the program the dimensions of my board.
    The example you can see I ask for a size A3.
    You can see that when I ask him to go home he is very far away.
    Do you have ideas to correct all that?
    My water bottles are 100g is ok?
    Thank you for your help.

    Bonjour Dan,
    Je me suis remis au test du makelangelo 3.2. Après plusieurs test j’obtiens toujours la même chose. Le dessin est décalé et le crayon ne retourne pas a son point de départ.
    Après plusieurs dessin j’ai changer dans les paramètres du programme les dimension de ma planche.
    L’exemple que tu peux voir j’ai demander une taille A3. Tu peux voir que quand je lui demande de retourner à la maison il en reste très loin.
    A tu des idées pour corriger tout ça?
    Mes bouteilles d’eau font 100g c’est ok?
    Merci pour ton aide.


    Start at home.
    Use program to move down 100mm.
    Use program to move up 100mm.
    Where is it?

    Start at home.
    Use program to move left 100mm.
    Use program to move right 100mm.
    Where is it?


    Thank you Dan for your responsiveness.
    One curious thing is the coordinates of x and z before I had x0 and z 0.
    Now I have the first picture.
    Even by saying “This Home”.

    Merci Dan pour ta réactivité.
    Une chose curieuse ce sont les coordonné de x et z avant j’avait x0 et z 0.
    Maintenant j’ai la première photo.
    Même en lui dissant “This Home”.


    Left motor appears to have trouble. Do you get same results with right 100mm, left 100mm?

    Are the belts skipping on the pulleys? (pulley turns and belt does not move)

    Are the 100g counter weights catching on the belt? (not pulling consistently)

    – disconnect power
    – remove clear plastic cover from brain
    – adjust dial on south side of green circuits 10 degrees clockwise
    – restart machine.

    Dial controls current to motors. more current = more power = hot motor!

    y=308 not unusual. 0,0 is center of paper. width/2, height/2 is top right corner (center of right motor)


    Yes same problem. obviously when I move from right to left and from left to right the pencil never comes back to the same place.
    Belts swerved on pulleys from time to time.
    The 100g counterweights are hooked on the belt and move smoothly.
    The motors are already very hot.
    I do not touch the setting on the green circuit because I do not have a small screwdriver. And I want to be sure that’s fine.

    Oui même problème. visiblement quand je bouge de droite à gauche et de gauche à droite le crayon ne revien jamais à la même place.
    Les ceintures sautes sur les poulies de temps en temps.
    Les contrepoids de 100 g sontaccrochés à la ceinture et bouge sans problème.
    Les motors sont déjà très chaud.
    Je n’est pas touché au réglage sur le circuit vert car je n’ai pas de tourevis assez petit. Et je veux être sur que c’est bien celà.


    yes, those are the dials. probably not the problem there.

    belts should *never* skip on pulleys. if they are skipping your robot has a problem. I can’t see why it is skipping from the information you have provided.

    I asked for a test in the other direction to see if it is an exact mirror image OR if one motor is more of a problem than the other. Can you verify?

    Are you able to draw A2 OK? Maybe A3 is too large, or your board needs to be more tall (so the paper is lower). You can tell the robot that the board is taller *without changing the board* and that will make the 0,0 position lower. it will also mean after “set home” you will see Y is a larger number. The benefit is that the pen holder will not try to draw at the top of the board where problems can sometimes occur (hitting the electronics, too much tension)


    yes it is the image c for the test. It’s not a mirror image. I am testing an A4 size letter size image.
    I tested 2 12V 2Acest power supplies ok.
    I tested A2 in A3, impossible in A4 too small apartment for the ficihier.
    It’s discouraging ….
    What is the ideal size of the board?

    oui c’est l’image c pour le test. Ce n’est pas une image miroir. Je test une image A4 taille papier à lettre.
    J’ai tester 2 alimentations de 12v 2Acest ok.
    J’ai tester en A2 en A3, impossible en A4 trop petit appartement pour le ficihier.
    C’est découragent….
    Quelle est la taille idéal de la planche ?


    For the bottom drawing, with the sharper lines, I put 250 g on the bottles. it’s not fluid on belts.
    But in the end he never returns to the good home


    My last test was done with the actual size of my board 80 cm X 120 cm. Which does not change much of the board of your tutorial which is 84 x 122.



    what if you slow down the machine?

    settings > pen > max speed=8000, draw speed=5000

    try 1000 lower each time until results improve.


    Hello Dan, excuse me for this late response.
    Curiously the program was set to settings> pen> max speed = 6500, draw speed = 6500. I followed your advice and said settings> pen> max speed = 1000, draw speed = 1000.
    You can see the result. It’s better. I put you an image with are back to the Home.
    Looking at the machine working slowly, it is the belt that jumps apparently, which creates shift. Can you tell me if the gear is well placed?
    Thank you


    It appears to be well placed.

    …. count the number of teeth on the pulleys. Long ago a supplier gave us 18 tooth pulleys that had “20” written on the side. We counted EVERY pulley in stock. Now I’m feeling paranoid that it could be happening again.


    20 teeth on mine


    Good news.
    It’s not perfect, but almost. I am on the right track. I unscrewed everything, including the notched wheel, one was not sere enough. Obviously the floor of the room where the machine is is not flat. I have everything upgraded. Maybe it was a swaying bottle. The return to the Home is not accurate. So I continue in this direction and I will give you a return.
    Thanks again Dan.




    Thanks again for all Dan.
    I put you a visual of a drawing size A2.
    And a little thing that improved the roaring.
    I put Teflon.
    I will make a more suitable frame.
    It is possible to buy Makelangelo 3.2 Laser Cut Parts on your website.
    Is it possible to buy the files instead? I would like to cut them out of thicker wood or pvc.

    See you soon,


    In fact it is mainly: 4 MECH-0077 m4e1 Makelangelo 4 motor mount.


    You might have some success with the M5 printer parts (instead of teflon):

    I will look into getting the DXF files online.


    Thank you for your generosity.

    I will test the printing of M5 printer parts. I have a Micro delta Rework for printing.
    And thank you again for the publication of your DXF file



    I’m also having offbeat drawing/movement. Granted I have a custom made version with spools and all.

    After following your tips here:

    How to fix 9 common Polargraph drawing problems

    I told the machine to move 10cm to the right and adjusted pulley pitch accordingly. Now having perfect X axis precision. However, Y axis is always off by 1-2 cm’s.

    What could it be?


    Your pulley pitch should be calculated from the number of teeth. For example, if you are using GT2 belt (2mm per tooth) and your pulley has 20 teeth then your pitch is 40mm.

    If your pitch is correct and your X or Y movements are wrong, check the measurement between both motors (machine width).

    Does that help?


    Well, I’m using spools, so there’s no pulley nor teeth. And I should say there’s no winding problem in my setup either.

    I started out using the the spool circumference for “PULLEY PITCH” – I’m assuming this is the right way to go? But then when it wasnt accurate, I re-did it with your formula in the link above. Now X works flawlessly, but Y is off. Probably if I re-do it, calibrating on the Y axis, the X axis would be off.

    With this in mind, you think it’s the drawing area measuements that are inaccurate? I’m using a ~1.5×1.5 area so there might be some minor measurement errors when I set it up. But I mean, it can’t be off by more than 1cm, and I am getting movement accuracy errors of 2-4cm. It seems a bit much off for such a small measument inaccuracy no?


    spools with string wound around them work poorly. each winding changes the diameter, which ruins the accuracy.

    There’s definitely a calibration problem, probably a measurement issue. You’re close, I can feel it. It doesn’t take much error on a polargraph to make a big difference.

Viewing 24 posts - 1 through 24 (of 24 total)
  • You must be logged in to reply to this topic.