Issue with calibration

[Anonymous]

Hi there,

So I have my Makelangelo up and running. I have drawn a few things with it, in order to test it. But I figured after some time that there was a configruation problem somewhere. My robot does not manage to “find” the edge of the paper.
So I looked at
https://www.marginallyclever.com/blog/2014/10/how-to-fix-9-common-polargraph-drawing-problems/
And I followed the instructions; however, I also realised that my Makelangelo does not manage to draw squares. It draws rectangles.
So when I want to do a 15cm*15cm square, it actually does a 14,5cm*15,5cm rectangle.
The pen is in the correctly centered.
Any idea how I might correct it?
Thank you!

[Anonymous]

What’s your pulley size?

[Anonymous]

I used 15 x 15.
At that point I had a vertical line of 8,5cm and an horizontal line of 7,5cm when I used Y+/-100, and then X+/-100.
I then used the formula
new pulley size = current pulley size * 10/A
To get a new pulley size. It didn’t work. 15*10/8,5 = 17,64 and with this pulley size my drawings were now 7,5cm and 6,5 (give or take, I didn’t measure these ones precisely as I realized they were smaller and not bigger.

So I used the formula
new pulley size = current pulley size * A/10

And now I use a pulley size of 12,5. And when trying to draw 15*15cm square, I get a 14,5×15,5cm rectangle.

[Anonymous]

i’m looking at my test machine and I see I have it set to 13mm each.

Also with the latest motor mounts I measure from the inside edge of each motor. The motors are 42mm wide. So if the board is 800mm wide, take of 42mm for a total machine width of 758mm.

Does that help?

[Anonymous]

Sorry for the late update.

So here it is. My board is 500mm wide. When I tried to draw 10cm line I had
Y= 10,5cm
X= 9,5 cm
I tried to do as you advised and configurated it a 458. I got
Y= 11cm
X= 9cm
So I then configurated it to 542mm (why not?) and I got
X= 10cm
Y= 10cm
And it is spot on.

I can’t really figure out why but it works :). Thank you for the help!
Now off to make beautiful drawings !

[Anonymous]

when you get a good drawing tweet and tag it #makelangelo so we can all see it. 🙂

[Author]

Posts