Needed: Cheap Gantry 3-axis robot

Not sure of the specifications yet, but in order to put together a funding proposal I need some basic ideas for cheap efficient gantry set-ups (table-top) with Accuracy: ~0.1mm Repeatability: ~0.01mm Resolution: ~0.01mm to 0.001mm Speed: 5-10inch/sec for x and y, faster for z axis Does anyone have any cheap/DIY suggestions?

KE7GKP: You must have a very different definition of "cheap" if you are looking for that resolution and speed. Good luck. I believe the RepRap project gets those kinds of distance and resolution, but nowhere near that kind of speed. If you want that kind of speed AND resolution, you are probably looking at something more capable (and more ($$$) than Arduino.

I'm not sure the Arduino would be the limiting factor; I think the limiting factor will likely be the hardware. To keep that level of resolution, repeatability and speed, you're going to likely need to use brushless DC motors (for the speed and torque), 16 bit binary encoders, and multi-start ACME thread screws (with anti-backlash traveling nuts) for each axis. None of that is going to be anywhere near cheap (heh - just price out the ACME thread screws if you don't believe me).

I actually think the Arduino could handle everything else (well, if you dedicated one Arduino per axis)...

KE7GKP:

I'm not sure the Arduino would be the limiting factor;

I was basing my evaluation on the stated desired resolution multiplied by the stated desired speed. But maybe with one Arduino per axis, it is doable. But that makes coordinating diagonal and arc moves more difficult.

You're right about that - something I forgot. I think I would tackle it in a couple of ways (of course, you'd probably have to use steppers for the following):

1) Implement an external clock to run each Arduino synchronously 2) Hook each Arduino up to the other two (two digital inputs going to a digital output on each of the other Arduinos)

(1) would keep all the Arduinos in time with each other; (2) would act as a synchronization mechanism, such that the Arduinos wouldn't send a pulse to their respective steppers until each Arduino read a HIGH from its neighbors - when all are in agreement, the step occurs.

Not sure how well that would work, but it'd be worth trying out, I think...

:)

This does not qualify as "Cheap" yet..., but Have you looked at the CubeSpawn project? its an Open Hardware project I'm working on - Its 3 parts away from running once it is running - I'll be using it to make parts for additional cubes - in time it should be able to make a lot of its own parts

I set out to use Arduino with it - and still will - but I'm focusing on the EMC version at the moment

see more here: http://cubespawn.com

And... Its currently in a contest until the 30th of june as well http://contest.techbriefs.com/machinery-and-equipment-2011/1531 a vote would be nice ;-)