Archive for November, 2013

Reprap Morgan SAE build

So far, here are my notes on building a Reprap Morgan using easily sourced parts in Iowa. Easily sourced means the metric bits need to be kept to a minimum. The rest was printed on a Reprap Prusa Mendel with a SeeMeCNC Steve’s Extruder and their Bowden hot end, using green ABS from Makergeek, sliced with Slic3r 0.9.10b with two shells & 20% fill. That feels a little flimsy on the thinner pieces – if I break something, I’ll probably re-print at 5 shells.

I printed the moving bits for the shaft – the two drive wheels & 4 arm pieces, plus the Bowden lock nut. I was surprised how well the nut fit – I thought my printer wasn’t accurate enough, turns out the spring belt tensioners I added work wonders. I printed the metric version & substituted hardware for what was close, and had fairly good luck.

For the main shaft I used a 5/16″ x 3′ threaded rod ($2.50 or so) a box of 100 hex nuts & a box of 100 washers ($10). the instructions call for a pipe crimped around two nuts to improve stability – I got a 1/2″ x 2′ copper pipe ($5). For the outer tube, I got a 3/4″ x 2′ ($7) that barely fit the printed parts. OK, it probably was too tight, but I’m pretty sure it isn’t going to slide around. for the “elbows” I got a 4″ and a 2.5″ x 5/16″ bolt, a little over a dollar for the two.

I did buy metric bearings. I didn’t know where to look for the 6805  (the one I got is labeled as an auto part if that helps), so I bought through Amazon ($7) and the 9 608 bearings are used in roller skates & skateboards. It was cheaper to buy a 10-pack off Amazon for $10, though.

As for assembly, the washers were too big for the bearings & caused them to grind, so they were skipped. Since this is just a test fit, I didn’t crimp the 1/2″ copper tube yet, either. But, with some gentle persuasion, everything fits!The copper tube may need to be seated deeper into the printed parts than I have it, but not bad for a test fit & guesses at the hardware store! Total investment so far is about $43.

I’m not a big fan of the stand design, so an enclosed one may be in my future. Maybe built as a freestanding table.

I’ll still need electronics (~$120), 4 steppers ($70), a J-head hot end ($50+), linear rod & bearings (?), heated build plate, fan… this is far from a cheap design.

Morgan column

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