Looks good. From just looking at the PCB, some suggestions:
1. Move the stepper boards as close together as possible, and allow for Molex KK connectors for the motor connections (same 0.1" pitch). Even if you don't populate the board with them, it gives you the option. Looks like you're VERY close to fitting them now.
2. Make the stepper motor drive lines as thick as you can make them.
3. Perhaps go for a mini-usb or micro-usb socket? Micro's are all the rage (everyone seems to have one with their phone), but the mini's seem to fall off PCB's less (they tend to have some pins like the shield through the PCB, whereas micros all seem to be SMD).
4. Perhaps a small cap between the USB socket shield and the board ground? (dubious idea, but thought I'd ask).
5. I'd be inclined to rearrange S1, C7 and C8 a bit to give D1 more room (the more it can dissipate, the better), and /or replace D1 with a different component to give better protection (depends on what it is now of course). I'd also make the cathode track from the fuse thicker (from the fuse just to D1's Cathode, not the rest), so that it's definitely going to blow the fuse and not the track.
PS: What fuse holders are those, and what fuses do they take?
1. Move the stepper boards as close together as possible, and allow for Molex KK connectors for the motor connections (same 0.1" pitch). Even if you don't populate the board with them, it gives you the option. Looks like you're VERY close to fitting them now.
2. Make the stepper motor drive lines as thick as you can make them.
3. Perhaps go for a mini-usb or micro-usb socket? Micro's are all the rage (everyone seems to have one with their phone), but the mini's seem to fall off PCB's less (they tend to have some pins like the shield through the PCB, whereas micros all seem to be SMD).
4. Perhaps a small cap between the USB socket shield and the board ground? (dubious idea, but thought I'd ask).
5. I'd be inclined to rearrange S1, C7 and C8 a bit to give D1 more room (the more it can dissipate, the better), and /or replace D1 with a different component to give better protection (depends on what it is now of course). I'd also make the cathode track from the fuse thicker (from the fuse just to D1's Cathode, not the rest), so that it's definitely going to blow the fuse and not the track.
PS: What fuse holders are those, and what fuses do they take?