February 7, 2012 – MakerBlock

DrawBot – Calibration

Calibrating my DrawBot was apparently important to its operation. Who knew?! If you’re following along at home, you’ll definitely want to check out Sandy Noble’s instructible on Polargraph calibration. I’ll put my settings here, but they probably won’t be that helpful to you unless you’re using the same exact equipment and hardware as I am.

Setup->MM per Rev = 50

Based on the actual spool center diameter, this should be 47. But, with some line wound onto the spool, it should be more like 54. So, of course, I chose something that was neither.

Setup->Steps Per Rev = 400

While my stepper motors have 200 steps per revolution, Sandy’s controller software uses an interleaved step system, the steps must be doubled.

Setup->Machine Width = 844

Although the “Machine Width” is defined by Sandy as “The distance between the two closest points on the sprockets,” I used a different figure.¹ Since my machine uses spools, rather than sprockets, and the spools are unwound on the far side of the spool, I measured from the far edge of the spool’s core the the other far edge of the other spool’s core. I figure this is probably the best measurement of the width of the line available to the machine.

Setup->Machine Height = 848

This is a relatively arbitrary specification given that my spools have about four times as much filament than I could use in my current configuration. I intended this to be 844, but must have typed it in wrong. :)

Setup->Page Width = 216

Rounded up from 215.9, which is 8.5 inches converted to millimeters.

Setup->Page Height = 279

Rounded from 279.4, which is 11 inches converted to millimeters.

Setup->Pen Tip Size = 0.12

With my 2’x4’x0.5″ board covered in butcher paper, I’ve marked out on the paper the locations of the various important lines for my machine.

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Heaven forbid I do something normal, right? [↩]

DrawBot – Why are you crying?

Starry Night by Van Gogh, drawn by a freakin’ robot with ADD

After about half an hour I noticed my drawing robot was not making the low scritchy scratchy humming drawing noise. I’ve started the drawing again… It looked like it should have been working, the controller software indicated it was still connected, the command queue was still loaded, the Arduino + Motor Shield were still lit up, but it just wasn’t moving.

In retrospect, I should just have hit the reset button on the Arduino. I think that would have made it pick up with the last command. But, then I wouldn’t have the lovely picture above to show you!

Actually, I’m really really happy with the drawing quality. Check out what it looks like when overlaid the subject image:

Starry Night by Van Gogh, drawn by a freakin’ robot with ADD, overlaid the subject image

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You know there’s something wrong when…

My office is about two blocks from a grocery store and many days I’ll just walk out there and grab a sandwich from the deli. As I was walking back I thought of something I might want to blog… but none of my current blogs¹ was particularly appropriate for this notion. For a full minute I actually toyed with the idea of starting a fourth.

Which, of course, is just pure madness. There’s no damn reason for one man to blog in four places across the internet. ²³⁴

Thankfully that moment of madness has passed and I have no recollection of the thought which prompted me to taste insanity just before my turkey wrap.⁵

I post two places regularly and on a third site very infrequently. [↩]
Unless, of course, schizophrenia counts as “reason.” And, I’m pretty sure it’s the opposite. [↩]
Or close enough to the opposite of reason when one considers the appropriate number of blogs per capita. [↩]
One man, one vote, and one blog seems about right. [↩]
Except for the lingering knowledge that I had some thought/idea that was so compelling I might actually decide to spin up a fourth blog. [↩]