Assembly IV: More Wiring

The mechanical assembly of the printer has been going well, but its time to work on the electrical side of things once more.

At present my 3d printer contains a 72V power supply for the servos, and a 24V supply for everything else.  I'd never really given much thought to whether I would need 12V, or where the 12V might come from.

Over time it became clear that many of the fans I would like to use require 12V, so I decided to discretely install a Pololu switching regulator in some of the unpopulated space of the X4 Smoothieboard.  The regulator powers the full set of small MOSFETs, which will be used to power fans.

I also printed a set of "locks" to hold the stages in place.  The stages roll freely back and forth when unpowered, which can be highly inconvenient if you are moving the printer around.

The fasteners are held captive within the printed halves to prevent them from getting lost (or worse - pulled into the stage by the considerable number of magnets within).

Finally I prepared the other half of the bed wiring.  I chose to cut the bed wires very short and terminate them with connectors so that the bed can be disconnected if necessary.  The connectors also let me to use high flex wire in the cable chain.

Here is a picture of regular 16ga copper wire next to high flex silicone wire of the same gauge.  High flex wire is stranded very finely which allows it to bend easily.  Regular copper wire is not designed for repeated bending and over time the thicker strands of copper can develop small cracks.

It can be very annoying to route cable though cheaper cable chain, but the Misumi stuff I'm using is quite nice.  The tabs pop open easily, but feel quite secure when closed.

The wires are secured on both ends of the cable chain with Velcro straps, although the photos aren't at the right angles to show it.

The cable chain exits into the space below the printer, allowing the bed wiring to join its peers in the cable nest.

I continued to make progress with the wiring and decided to test fit the back panel as well.  Its not a particularly difficult task, but routing wires can be slow since there is already so much stuff in place.

I also chose to include an e-stop switch.  An emergency stop isn't strictly necessary, but I have a thing for illuminated switches.

The e-stop will directly cut mains power which keeps things simple.  I would have preferred to use the better looking Omron A165E-LS (one of my favorite switches) but those cost a staggering $90/ea so I settled for this Misumi switch instead.

Here is a final photo after all the wiring has been completed.  The fork terminals on the right side will connect to 24V, and the fork terminals on the left will connect to 72V.  I ended up using orange/blue/green for hot/neutral/ground as I was running out of black wire.

At this point I'm 95-98% sure that the printer will work, but failure could be extraordinarily expensive so I'd rather not take any risks.

Instead of powering everything up at once I'll poke around with a multimeter and test incrementally.  This will be very slow, but should limit damage if I've made any mistakes.

1 comment:

Rowan Meara said...

This build is really exciting to watch. I've been thinking about making a more rigid printer, although not quite this insane, and look forward to seeing what the benefits are. Your documentation of the entire process has been amazing!



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