This weekend I got busy with the boring job of wiring. I decided to use old-school 9-pin serial leads and plugs for my electrical conduits, mainly because I was trying to avoid any sort of soldering and the sockets I bought from JayCar let me get away with glue gunning!
All-in-all, the wiring job was pretty successful – I got the x- and y-axis motors and end stop switches wired up and ‘working’.
Unfortunately (as suspected) when I powered everything up my little 42mm NEMA17 stepper motors and Pololu A4288 drivers struggled with the torque needed to spin the drive rods. They stall and start squealing. When you step back and look at them on my Behemoth, the motors do look a little weedy- like 4.5HP outboard motors on the side of an oil tanker. In retrospect, if my drive rods weren’t so clunky and misaligned the little soldiers could probably pull it off, but as soon as any load came on them when I was actually milling it would be an issue. Anyhow – I’ll be looking into beefing things up torque wise. I am considering them a ‘proof of concept’ at the minute.
The control box and one of the two X-axis motors. The electronics is a Protoneer CNC shield on an Arduino: you can see Pololu drivers on top – the elements with the black squares on (these are the TI chips that overheat and cause stall) The three serials ports on the end of the box are for y-axis, z-axis and spindle control respectively.
As above but with the control box lid closed. Yes- it is made from a (Caro) wine box. This is a reoccurring theme. In time I shall be sticking a RaspPi in the box with a touchscreen mounted on the top face.
The other x-axis motor. Too small right? You can see the serial lead going into the control box (yes, it’s a slice of a wine bottle box). The red wire goes to the x-axis end stop: when the bridge upright closes the switch it zeroes the x-axis.
Thank you Caro. Nothing new here that wasn’t in one of the previous photos. Incidentally, the grey aluminium the serial sockets are attached to: that’s a ‘flashing sample’ from work. Thanks ‘We-have-a-prefab-idea-for-school-classrooms’ people.
Another angle of the same. I think I’ll only need the z-axis port. You’ll see there is a ‘Z’ on both faces – this is just a pass through so cable doesn’t get minced by the tool. BTW, the thing in the background, framed by the CNC control box, the lid and the bike wheel is my bike holder – it’s fixed to floor joists.
The y-axis end stop switch (end of the red wire). When you have a 3000W motor with a cutting tool attached it to, it is important that the machine knows where to stop.