Here’s a quick demo of the pen arm in action:
I’m pretty happy with how it’s working. Now I just need to get the drive train working. I think a few things are conspiring against it at the moment:
- Underpowered steppers - I’m intentionally using smaller steppers to keep the cost down, but powering these from 5V USB means they haven’t got much power. I’m going to use a 12V battery pack to get a bit more out of them.
- Drag from the USB cable - the only USB cable I have is pretty stiff so puts quite a lot of drag on the bot. I’ve got a bluetooth module I’m going to use which, in combination with the battery pack, should cut this out of the equation.
- Lack of grip on the wheels - I tried running an elastic band around the main wheel which did work a bit, but quickly slipped off and made things worse.
- Not 100% sure I’m driving the steppers correctly so I need to double check that too.
Now I just need to find the time to sit down and dig into it.