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Author Topic: What motor size is needed to build a big polargraph
Televio
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Posts: 3
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Post What motor size is needed to build a big polargraph
on: February 14, 2013, 15:03
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Hi,

I want to build a big polargraph with an drawing area of 2m x 2m. Is this possible with Nema17 motors used in 3D printers (Holding Torque: 43.15 N-cm)? Or are they to small?

--
Andreas

sandy
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Posts: 1317
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sandy
Post Re: What motor size is needed to build a big polargraph
on: February 14, 2013, 19:35
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Hi there, even a very weak motor will be able to move the gondola around accurately if you move slowly enough, and have the right counterweight.

The problem is that any combination of gondola and counterweight will have a certain "sweet spot" where the gondola naturally hangs (usually in the middle of your page somewhere), and it takes torque to lift it out of that happy zone and up to the top, or push it down to the corners. You can increase torque by increasing current, but expect to run hotter too.

That said, it's all proportional. If I built a 200cm2 machine with my motors, I'd expect to be able to draw a panel around 120-140cm2 in the middle, so I sacrifice about 30-40% of the machine area. If I wanted to draw a 200cm2 panel I'd need a machine that is 280cm2.

Some other things start happening at that size too, the main one being that when the gondola is high up at one side of the machine, the long string might tend to hang under it's own weight. I would switch to using a lighter thread, a non-beaded one.

sn

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