Distributed Solution Simplifies Hot Rod ROBO

I took yesterday off of the Hot Rodding mission because I needed a break from it.  Too much of even a great thing can be a bit overwhelming and cause loss of interest which would kill the project so I rested.  In the morning during the wee hours, I sat by the ROBO and stared at all the wires that I had pulled out and that were dangling all over the place.  Surely there must be some way to simplify this.  Here is a repeat of the photo that shows the wires:

Reduced to it's base and guts, the ROBO is ready for customization!
Reduced to it’s base and guts, the ROBO is ready for customization!

Now that is one tangled mess of wires, or more specifically an untangled mess of wires.  I like to think that my best ideas are supernatural in nature, the evidence for this being that they really are “light bulb” moments, or epiphanies, not some gradually well thought out evolution of an idea.  Be that true or not, this was a bright spark of an idea – I imagined putting a small circuit board on each of the five steppers.  Now that I have a better (but not fully complete) feel for exactly how much circuitry is required at each stepper (heaters are a bit fuzzy but clearing up), I can imagine putting the circuitry for each stepper on the stepper itself.

If I also put the linear regulators, which will be LM317T’s (adjustable positive linear regulators in TO-220 packages), on those stepper boards then I need only run power and control – just three wires – to each stepper.  For the extruder and the heated bed steppers, a second board on standoffs can do the job of running those circuits.  This then becomes a distributed circuit rather than a centralized circuit.  The nature of the system is such that a centralized approach is less desirable because of all the wires.

Let’s look at the most complex part of the system as far as wires are concerned, the extruder carriage.  It has two wires each for two fans (4 wires so far), two for the heater and two for the thermistor (total now 8 wires), four for the stepper in a bulky insulated cable sheath (12 wires total), and i think that’s all, so yeah 12 wires to that thing and some of them larger wires too.  No wonder the ROBO designers used a big snake of a cable to the extruder carriage.  This cable snake caused issues for me when I tried to use the full height of the ROBO and the snake caught on the exposed ends of the Z riser rods, causing the machine to go kachunka-kachunka in a scarily violent manner until I managed to panic and hit the power switch.  This happened twice and I realized that I could not use the full height of the printer on my particular shipped device.  With only three braided wires, this problem is reduced or eliminated.

The rest of today’s efforts on the ROBO hot rodding project will be spent on putting in a jameco order.  Jamaica is a good low cost supplier to hobbyists and they have all that I need or most of it, so one stop shopping is the winner here.  See you next blog entry, and I hope you enjoy the ideas.

Les

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