Tuesday, 14 January 2020

Upgrading the Sculptor: Bondtech BMG gearing, Silent fans, and Thermistor replacement

Sculptor ready to print
    Time for some 3D printer upgrades! This time it's the Sculptor i3MK2.3 under revision, specifically the print-head assembly. After refitting my Ender 3 with Bondtech gears during the early fall. I was quite impressed with how reliable they after a couple hundred hours of printing. So when a decent quality clone of the BMG turned up on Amazon, it was time for a much needed upgrade and overhaul for my second oldest printer.

E3D Thermistor and Capricorn XS PTFE tubing.
New (top) and old (bottom) E3D thermistors
   First step of the upgrade process was to strip down the existing tool-head and check the electrical parts for any issues that may have come up over the last year or two of use. One issue that I'd been aware of going into this refit was a bad bearing in the hot-end fan, but as soon as I removed the part fan it became clear that there was a major safety issue with the thermistor cartridge, specifically that part of the insulation had frayed away from the wires it was supposed to protect, that could cause a fire if the control board glitched at the same time, so getting a replacement became the top priority for this upgrade cycle. Fortunately it turns out that E3D had already fixed the manufacturing fault that caused the issue, so I ordered a couple of the updated version, one as a replacement and one spare for future repairs.

Secondary extruder gear installed on idler arm
    Bondtech actually has a specific kit of the BMG that is meant for refitting an i3MK2, so there are SLS optimized source files to work from for the printed parts, fortunately I found an FDM optimized remix on Thingiverse (thing:3347150), so it was just loading the parts into a batch on one of the other printers, cleaning off supports and starting assembly using the online instructions from the official kit as a guide on what goes where.

Gearing system half installed on motor
Assembled Tool-head bolted onto gantry
    Once the mechanical assembly was done, it was time to sort out the electrical issues that had cropped up. Since I had the tool-head apart anyway, the hot-end got stripped down to components and refitted with new parts, Capricorn XS PTFE for the barrel lining, a fresh nozzle and the replacement thermistor, all fairly simple refits but you do have to dismantle the lite6 hot-end to do them. With that side of things done, it was time to deal with the worn out fan.

Fractal Designs Silent Series R3 4010 12V fan
     My local computer store turned out to have some nice 4010 fans from Fractal Designs in stock, so I picked one up to test it out and see how it compared to the Noctua model on the Mega Kossel. Visually, they're quite different, the Noctua has a smaller core with larger blades whereas the Fractal looks more standard, but sound-wise they're about the same when powered up, so I'm fairly happy with the Fractal Designs model and I'll probably be using them in future refits.


Fractal Designs fan installed and ready
     Once all the fans were mounted, it was time to calibrate the extruder and do a test print. Instead of the usual 3DBenchy, I decided to try the Lattice Cube by Lazerlord (thing:1850320) and see how it turned out. 6 hours of overnight printing later, I was greeted by a nearly perfect print when I came into the workshop to check on it. Overall I'm expecting this upgrade to keep the Sculptor running reliably for several years to come.


Lattice Cube freshly printed