Only works when the drawing is simple?

[Anonymous]

Hello,

I am living abroad for a few months and was looking for a small project to play with. I am captivated by makelangelo and wanted to try to make one. I was surprised to be able to source most of the parts to build one within walking distance of where I am living in Amman, Jordan. I am having some trouble, though, and hoped someone on here might be able to help me.

I am using an arduino Mega clone, a v1 motor shield clone, and some used 3.2v 1.2a 200step stepper motors. I found some belt and some belt pulleys and had a gondola printed locally.

I do realize that I have problems with my stepper motors. They are 1.2a but the v1 shield is rated for .6a/1.2peak. The chips on the drive do get quite hot. I have popped some heat sinks on their for the moment and am trying to source more appropriate motors. So far I have not been able to do so.

The above may be the source of my problem, but Im not sure.

If I feed the machine a very simple drawing, a simple dragon fractal or hilbert curve it seems to work:

This is the best result I’ve gotten, with the pen lift working and everything.

With a slightly more complex pattern it looks pretty good, but the whole figure is shifted down relative to the frame:

But when I try to draw an actual image, it just doesn’t work. It seems to lose a few steps all the time. This is some scrap paper where you can see the pink ink is a few attempts at a sandy noble style but each pass of the gondola is not lined up with the previous pass. And the black was an attempt at a spiral, and you can see that the first two circles don’t line up and the second circle is slightly bigger when it should be smaller.

Finally, here is an attempt at a relatively simple zigzag. It sort of starts off OK, though I think it might be crossing over itself when it shouldn’t be, but then it wanders up off the page. It seems like it goes wrong when it is trying to make lots of direction changes.

Is this possibly a function of my motors being borderline undriveable by my little shield, or is it a setting somewhere?

any feedback would be greatly appreciated. Thanks!

[Anonymous]

Oops, posted before checking carefully. (Sorry about the there/their typo)

Also the 3rd picture didn’t post:

[Dan]

I’d fix the known heating problem first and try again.

[Author]

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