Sunday, 27 November 2016

Project: Proteus Delta part 5

Proteus Delta with current rod arms
     Last time, I'd just finished installing the steel rod arms, but I ran into a problem with 6 of them being too heavy for the motors to hold at the top unpowered. I replaced 3 of them with wooden shafted ones after some weighing and experimentation that showed the max unpowered holding weight of all 3 motors is around 900 grams or 300 grams per motor. 

Wooden rod arms being assembled
How to use 6inch/150mm calipers to measure long objects with some markings
     I'd mentioned measuring the rod arms in part 4, but didn't include details on how that was accomplished. I just wrapped some small pieces of electrical tape around the rod arms roughly 1/3 of the way along from each end as reference points, then measured the lengths of each section of rod, that puts my accuracy at +/- 0.03mm, since my calipers are accurate to +/- 0.01mm. The updated average length is 396.54 +/- 0.03mm, and that finishes the rod arms.
Left to right: Power supply bracket, 5x20mm 5A fast-blow fuse, power plug/switch
     After sorting out the rod arms, it was time to start on the electrical harness. I've already installed the motors and end-stops, so the power plug/switch unit is next. For wiring up one of these 'Power switch with fuse and socket' units I followed this guide by, it covers all of the details of setting up the mains wiring correctly. For the housing, I'm using a remix of this power inlet mount, with some added extra flanges to allow it to fit on the electrical conduit with the help of a shortened variant of the alternate conduit mounting brackets from the Emmett-Delta design. The printed parts are connected with 2 m3x50mm screws and a couple of m3 nylock nuts.

Power supply wired in and ready for securing
Power supply mounted and secured
Duet 0.8.5 mounting posts

     With the power supply fully installed, it's time to mount the Duet 0.8.5 onto the base and plug in the motors and end-stops. Since the Duet is designed to use function as a heat-sink for the stepper drivers, I designed some printable mounting posts to provide space for airflow under the board. Once mounted, it's mainly just a matter of plugging in the motors and end-stops to the relevant pins, which are helpfully marked on the underside of the board. It's worth noting that for micro-switch end-stops, the leads need to connect to the outer pins of the 3-pin connector, not the center and one side used on a RAMPS 1.4 derived board.

End-stop connector for Duet
Duet 0.8.5 mounted and partially wired
     That's it for now, my next step is to sort out the wiring pinout for the power supply's output, so I'll be breaking out the multimeter next time for exploring what pin gives what current level, along with mounting the cooling fans, but that's for next time.

End-stop wire routing at the top of the towers
End-stop wire routing at tower base, note the zip-tie retainer on the right
Proteus Delta almost ready for motion testing
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