Yesterday I also asked one of the lab techs at uni about an issue I had previously stated about controlling the steppers with a slave controller or not. He said that he had done both previously and said that it really depends on the grunt of the master controller, as it should be doing error management on top of just the control. So with that in mind I think I'll use slave controllers to manage the steppers. Talking of which another conundrum I've come up with is how to operate the Z plane. I've decided telescoping is too complex and would also be more flimsy compared to moving the entire frame. This has made me think how many steppers to use for the Z direction. If I have two it means that at any point in time one of the other two plane could be on an angle which would be bad. I'm thinking I will probably just use two motors and make the frame more rigid by how its mounted onto the pylons in the corners, maybe having a second join on the Z slide round the back of the pylons, though this would make it slightly harder to mount a case. This is also a problem as the weight from the XY steppers will mean there is more force in certain places compared to others. The stepper motors are only around $20AUD so maybe its better having three Z steppers as it might be cheaper all up. Another issue I had raised previously was the weight of the ball screws. I've decided these aren't a problem as they won't weigh much relatively and other materials will most likely deteriorate quicker.
One last thing was that I had a quick look at development boards for the electronics today on element14 (Farnell) and I'm thinking either the Texas Instruments: TMDXDOCKH52C1 - H52C1 Concerto Experimenter Kit or FreeScale Semiconductor: FRDM-KL25Z - FreeScale Freedom Board. Most of the others they had on offer were much more like a computer on a board rather than basic development boards. I think I'll start off with one of these and get a feel for how they work and then if needs be design my own board. I haven't looked into the slave controllers but I'm thinking of using either TI MSP430s, Atmel ATmegas or a Microchip PIC. The TI MSP430s I have at the moment seem to not work as well as they are made out to, even when simply copying example code so I will most likely use one of the other two.
