mScara: Very Shaky and inaccurate

#1

Hi,

I just received my mDrawBot kit today and built mScara. Everything appears to work, but unfortunately the drawing accuracy is not very good. The lines are very shaky, which bothers me more than the lack of accuracy, here is a video of one of the sample SVG’s included in mDraw. Here is a video of it (vertical video warning :smiley: ): http://youtu.be/GmXNI6ZEjOI

Unfortunatelly I can’t upload images (because I am a new user…), but as you can see, the circle is not properly closed and in the top right the lines are very shaky (you can even here it during the drawing that its shaking more at that part of the drawing). I tried a bunch of different things mechanically to reduce the shaking, but even without the pen, the shaking is there. Any ideas about how to fix this, or is this as good as it gets?

Thanks!

#2

Hello

Give you some suggestions

  1. Make sure you have tighten each screw.
  2. Change a lighter and smooth writting pen
  3. adjust the steering angle when put pen to the paper
  4. make sure your desktop is smooth

Thanks

#3

Hi Everyone,

      Ive received my Mdrawbot today and after spending all afternoon trying to make the mscara to work i totally gave up.
      I have taken everything apart 2x times to check every screw and connection but still no luck.Everything powers on and all led lights that supposed to be on are on.

When the whole thing starts to move, it just goes all over the place and is very shaky to. It moves like crazy, not even on the right direction when i try to move it manually.

All screws are tighten correctly and i even pulled up the pen so it doesnt touch the paper(so makes it lighter to move), even this way all crazy things happens.

Drivers has been installed and proper software to. tryed many arm positions and everything i could think of but still no luck. Ive uploaded a quick video on youtube so guys could check into details and possibly help me.

PLZ PLZ PLZ PLZ PLZ HELP

Many thanks

#4

Your drawing looks quite all right, take a look at mine:

I guess there are two problems:

  • shakyness of the whole thing
  • accuracy (the thing should complete a circle even if it was shaking on the way)

As for the shakiness I was thinking of using the caster wheel to add support at the end of the first arm - but all the parts are actually in use for mScara, and since it’s my first kit - I have no way of attaching it :expressionless:

As for the accuracy - so is it a problem with tensioning?

I checked:

  • the screws
  • wiring (so it’s not in the way)
  • arm position during the draw process (so it doesn’t bump on the base on the way)
#5

Did you try to tighten the belts as this guy suggests?

#6

Hello @smulork and @mokafolio and @Vexatus

I give you guys some suggesttions

  1. PP02L%8P}}J1A}O~YF3F_GN.jpg975x758 259 KB

make sure the value of arm length is set correct.
2. There have a rotary knob on the motor module, in general, it should be rotate to the largest, you can try to contrarotate it a little (if the electricity is the largest it may cause the stepper motot shaky, if the electricity is too small, it will lose steps)

QQ截图20150523123315.png303x572 249 KB

Thanks

#7

@mokafolio
Alright, so I got mine just yesterday and set up the scara and am experiencing the same issues. By adjusting the pen such that it just BARELY touched the paper, I got smoother results, but still not as nice as I would like. The whole arm itself shakes as it moves. I did a calibration test by drawing a circle, and it did not close it. If I had to guess it would be because of the angle of the pen. When pushing it is angled back, and when pulling it is angled forward. So it may not be in the same relative location to the arm even though the arm is in the right spot. (Just a theory)

@smulork
Unpower the scara, then in software press the “Home” button. Now align the real arm to the virtual one in software. (Straight to the left). Finally power back up the device. Both with now be “Calibrated” to each other.

From here you can click once anywhere inside the drawable area, this will cause the arm to move and place the PEN wherever you clicked. (I was trying to do this click/drag thing early on… and that doesn’t work) If the pen still does not go to the same place, try switching motor1 and motor2 on the Orion… I had them backwards at first.

@Vexatus
I thought about adding a caster as well… one of the faults with this design is that the straighter the arm is, the greater the moment. This means that the pen is actually closer to the paper when the arm is straight rather than when it heavily bent. The increase of pressure on the pen when drawing causes inconsistencies. Something like a caster would alleviate that and most likely help with the accuracy, but I don’t know if it would help with the shakyness.

EDIT: responded to Vexatus

#8

My mScara is shaky also, changing power settings on motor drivers does not help at all, it seems that shakes are from motor “stepping” and length of the arm, what I also noticed that the speed setting on mdraw does not work the arm runs as quick on 1% speed as on 100%. Mdraw needs still lots of work (like errors on the terminal window, new setting do not stay after restart …)
Could makeblock please fix the speed setting ?

#9

Yes, your video is very shaky and the round is not “round”. Did you follow the latest manual of mDrawbot here?
If you still didn’t solve the issue, please contact product manager albert@makeblock.cc to solve it immediately.
Sincerely,
Una

#10