trembling line makelangelo

[Anonymous]

hello everybody

I’ve a problem with the drawing, the line is not exactly straight.
You can see it on the picture.
I’m working with an arduino uno, a motor shield V2, two stepmotors 5V with an external supply.
I’ve made some weight with bottle and water.
Is it normal or can i do something to fix that.

thanks

[Anonymous]

I would need to see your pen in action to figure out where the shake is coming from.

The not-straight line could be from starting off center, or your pulley size could be off a little bit.

[Anonymous]

ok
this is a little video to show you how it works.
the pulley size is good and i have shorten the belt but it’s the same thing…

[youtube:1v3dz06o]p3EyfTK6tLM[/youtube:1v3dz06o]
[youtube:1v3dz06o]fZkGH3cabfY[/youtube:1v3dz06o]

what do you think about it?
thanks
jm

[Anonymous]

i would try a bit more weight on the pen holder to cancel out the vibration. I’d remeasure the center point to be sure I’m starting in the right spot.

https://www.marginallyclever.com/blog/2014/10/how-to-fix-9-common-polargraph-drawing-problems/
might also help.

[Anonymous]

hello

i’ve try to put more weight and i’m sure about the center ( i followed your instruction), but it’s the same problem.
is there something to do in the arduino code? Because when i tested on another program like polygraph, the motor turn with not vibration.
i order another stepmotor in 12v to test with it.
thanks for your answer.

i’ve got another problem. The drawbot not return to the home position.
the pulley size is good, when i’m testing top,bottom, left, right, the pen return exactly to the start home position.
But if i’m drawing a square, the drawing is not center in the page and when i’m return to homme position there is a interval with the first home position (about 1cm on top and 1cm on left).
i’ve remeasure the center point and it’s perfect.
I don’t understand why. It’s not a problem with the spiral, scanline, or big zig zag but with crosshatch there is a big interval in the weaving ( not with the vertical and horizontal but with the oblique layer)

ps : sorry for my english i’m french..

[Anonymous]

i find a part of my problem.
I used some too long cable to the motor, it’s probably why one of the motor was very hot and trembling.
i placed the arduino beetwen the two motor and i think it works better

the second problem is the return to the home position.
I’ve made somme test, draw lines by returning to the center position between each.
As can be seen on images there is a lag.
Is what the problem could come from the motor power?
I’m using two nema17 2,8v 1,7A by phase and a power supply 5v 3,3A.
I also tested with two different motor (nema 17, 400 steps, 3v, 1,7A by phase) but the problem remains the same.

[Anonymous]

One motor isn’t receiving every step command. I’ve seen this before. It could be faulty wiring. I swapped the stepper that gave me trouble for another and the problem went away.

[Anonymous]

yes, but i’ve test with two different motor and it’s the same thing.
is the problem could come from the shield adafruit?

[Anonymous]

If the motors were swapped and it made no difference then that would be the next thing I would investigate.

[Anonymous]

the problem came from the power supply.
I’ve testing with a switching power supply and every thing is ok.
it works well with a power well below that the motor.
My motor is 3V 1,7A and the power is 2,6v 1A….

[Anonymous]

yay! Glad it is fixed.

[Anonymous]

thanks for your help…

Tomorrow I will try to make a bigger picture.
With the exeption of the measure I have to adapt, do I have to change something?

[Anonymous]

Uh… I’m not sure. We’ll know more after you try a test pattern again.

[Author]

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