The Egg-Bot Kit

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The Egg-Bot Kit Powered By Docstoc
					We have mentioned Eggbot several times this year as we demonstrated it at Maker
Faires in San Mateo and Detroit, as well as at the California state fair. And today,
we're very pleased to (finally) reveal the the design of our new kit.
 So what's an Eggbot? It's a machine capable of drawing on spherical or
ellipsoidal surfaces. You might say, a pen plotter for spherical stepper driver
coordinates. Or a simple but unusual CNC machine, ripe for hacking. Or an
educational robot-- and you'd be right on all accounts.

 It's worthwhile to point out that there's actually quite a bit of history here
in this project. The Eggbot kit is the result of our collaboration with Bruce Shapiro,
Ben Trombley, and Brian Schmalz. Bruce designed the first Eggbot back in 1990, and
there's been a process of continuous evolution ever since.
 The Eggbot has a rigid but adjustable chassis that allows you to mount spherical or
egg-shaped objects of various sizes, and stepper driver manufacturer rotate them
about their axis of symmetry using a stepping motor under computer control. A
second stepping motor moves a pen about an axis perpendicular to that "egg" axis,
and a small servo motor raises or lowers the pen above the egg surface.

  Above, you can see how we adjust the eggbot adjusted for drawing on ping-pong
balls. Below, a somewhat larger object: a medium-large "vanity" lightbulb:
  One of the major components of the chassis is this set of five individually routed
0.100" (2.5 mm) fiberglass shapes. These are actually fabricated in a circuit board
process. Their thickness makes them significantly more rigid than normal 1/16"
circuit boards. There are a few reasons for the circuit board process-- the primary one
is that it makes our robot remarkably rigid and durable. A side benefit is that we can
use the copper layers to form integrated heat sinks for the motors.
  The Eggbot kit includes Brian Schmalz's EiBotBoard (EBB), which includes a
USB interface and dual microstepping bipolar stepper driver. With its 16X
microstepping and the 200 step/rev motors, we get a resolution of 3200
steps/revolution in each axis.
  The EBB also controls the little servo motor that raises and lowers the pen arm. In
previous versions of the Eggbot kit, raising and lowering the pen has usually been
done with a solenoid. But the servo motor allows very small, precise motion to raise
and lower the pen over the surface. The end of the pen arm is hinged with an acetal
flexure for precise bending, and the pen arm clamp fits ultra fine Sharpie pens and
many others.
  The EBB also controls the little servo motor that raises and lowers the pen arm. In
previous versions of the Eggbot kit, raising and lowering the pen has usually been
done with a solenoid. But the servo motor allows very small, precise motion to raise
and lower the pen over the surface. The end of the pen arm is hinged with an acetal
flexure for precise bending, and the pen arm clamp fits ultra fine Sharpie pens and
many others. stepper driver supplier
  There is, of course, much more to the design in detail.
 Our web store is now taking pre-orders for Eggbot kits. And, as we move towards
shipping over the next couple of weeks, we'll be posting documentation here.

 Eggbot is now an open source hardware+software project, and we'll be posting
the design files as well as user documentation and example code.

				
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posted:2/12/2011
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