I'm just starting with building Phill's 3977 board, its an excellent chip, the boards Phill has designed are perfectly suited for the hobbiest and you can get the chips from allegro as samples. I had a ucn5804b 3 axis board running my small router and blew one of the chips when i went to a higher voltage. Those chips are obsolete so i decided to build the 3977 board, i also have plans to build the picstep boards for my next mill. I have played with the sla7051 chips as well as the lmd18245's from national that the picstep boards are based on. Theres lots of options out there. I'm still working on a serial interface rather then using the parallel port, using pic18f452 chip. I even built my 30 volt power supply with help from guys on the site. Basically comes down to what you want to do.
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Have a good one.
Dave |