Good question, I knew I should have an answer ready for that :)
Sources for which exactly?
ATM, the world lacks a plug'n'play expander board. Certainly something could be lashed together with a Sanguinololo or stripboard, but Reprap deserves something better.
I am working on EXT4, I have just sent off gerbers to get some PCBs made. It will be a cheap and simple solution, and compatible with any base board.
RepRapPro also have an expansion board, not sure when it goes on sale. It's designed for their Duet board, but is probably usable with other boards. (The Duet solution is a bit pricey I think, although it has some nice features).
I am thinking that the 6 axis motion would form an interesting challenge on it's own, and tool heads could be considered later. One thing I am keen to evaluate in a prototype is whether a Cortex M3 or M4, is able to handle the real time math, or if something bigger is required.
NXP have an interesting dual core chip, a Cortex M4 plus M0. The M0 could handle stepper driving and acceleration profiles, with the M4 doing the user interface and number crunching. The great thing is all these chips are around the same price as an ATMega256, with much greater capability, and that trend is likely to continue.
Right now, I wouldn't push anyone into buying RAMPS-FD, there is a new revision coming up soon which fixes several issues, but v1 is usable for prototype work.
Sources for which exactly?
ATM, the world lacks a plug'n'play expander board. Certainly something could be lashed together with a Sanguinololo or stripboard, but Reprap deserves something better.
I am working on EXT4, I have just sent off gerbers to get some PCBs made. It will be a cheap and simple solution, and compatible with any base board.
RepRapPro also have an expansion board, not sure when it goes on sale. It's designed for their Duet board, but is probably usable with other boards. (The Duet solution is a bit pricey I think, although it has some nice features).
I am thinking that the 6 axis motion would form an interesting challenge on it's own, and tool heads could be considered later. One thing I am keen to evaluate in a prototype is whether a Cortex M3 or M4, is able to handle the real time math, or if something bigger is required.
NXP have an interesting dual core chip, a Cortex M4 plus M0. The M0 could handle stepper driving and acceleration profiles, with the M4 doing the user interface and number crunching. The great thing is all these chips are around the same price as an ATMega256, with much greater capability, and that trend is likely to continue.
Right now, I wouldn't push anyone into buying RAMPS-FD, there is a new revision coming up soon which fixes several issues, but v1 is usable for prototype work.