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Topic: Wall Plotter, the Frankenbotic Thinganator, Alpha test (Read 7 times) previous topic - next topic

focalist

Yeah.. Seen the RepRap.. Out of my price range for now.  Of course there's nothing stopping anyone using this fishing-line design with a an extruder I suppose... Who knows what nonsense this will lead to!
When the testing is complete there will be... cake.

focalist

#6
Jun 19, 2011, 08:10 pm Last Edit: Jun 19, 2011, 09:05 pm by focalist Reason: 1
An intermediate stage video from the other day, just showing a bit of geometric drawing.  I think the point that I was try to get across- somewhat reasonable x/y pair plotting- is kind of lost anyway.  Other than seeing the very clear "pixelation" of the line (I'm using a slightly modified version of Bresenham's line algorithm.. I'm hoping Bresenham will be as helpful at arcs..), you wouldn't know it wasn't just some kind of rhythmic periodic pendulum or something.  Not the effect I was looking for.  A better exhibit is in progress.

http://www.youtube.com/watch?v=puoAsZ_kQD0

I'd recommend muting the music, I had youtube assign something Ambient at random, and honestly it's pretty irritating.  Looking into how to re-replace the audio.  However, it will be superceded in a short time by something much better.. Text Plotting derived from G-code.

I'm in the process of implementing a very basic g-code interpreter (pen up/down, x,y absolute... that's it at first).  The text print ("Arduino Rocks") is actually running as a series of 1200 lines of Arduino code similar to:

line(232,10,235,12);

derived by stripping down a Gcode set produced by DeskEngrave.  I cheated and stripped out everything but the x,y pairs, and used an Excel macro to make it into the line statements.  All I really need to do is perform that parsing on the Arduino itself.. sscanf will do it.  It seemed a reasonable enough idea to test what the output would look like..

As you can see, the first attempt didn't work out as well as I had hoped, but it clearly heading in the right direction and shows proof of concept.  I still haven't implemented Pen Up yet, but there's a reason for that.  Dry Erase is just testing.  A little math will fix up the problem encountered below, at least the being upside down part (LOL):



I do have to address the arc problem.. going to have to come up with a reasonable formula to calculate in to compensate for the geometry.  Anyone got a good solution already on hand?  As I see it, I just need to compensate for the arc at any given radius, so a formula should be workable.. and probably something I ought to know.. or knew once, long ago, when I needed to, for a grade.  Something about the two motors being chords on the arc, which then you can use to get the radius, which you then apply an adjustment for a circle offset by the radius at twice the distance?  Wikipedia, and a headache I'm sure, are coming..

Will this be it for the Thinganator?  No.  We're just getting started ;)



When the testing is complete there will be... cake.

focalist

Hehe.. Okay, still a little code work needed... and I think I actually parsed out some lines... but here's that phrase we all know so well:



Hello, World....
When the testing is complete there will be... cake.

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