21 Jul 2012

3D printers: and then there were three

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It has been a month of good progress within our Reprap 3D printing project. Within another month we hope to have three Repraps running. Several of us have picked up knowledge from our first printer and are starting to understand many issues related to how to run them efficiently, and what sort of objects they are best at printing, etc.








Mork (Reprap #1, the Green 3D machine)

Mork has undergone quite a significant amount of rebuild to fix various performance issues that have materialised over the past couple of months. Mork has gone from unusable to almost fixed, and we expect to have it fully performing again shortly. It is still a mess of wires and loose cables, but at least it is functional. Some of the issues we have addressed and hopefully fixed are :

  • Off-square frame. This might be a progressive issue as various frame nuts are often shaken loose by printer vibration. We need to look at lock-nuts, double-nuts, and/or Locktite on all 3D printers.
  • Broken idler pulley. This was craftily replaced with a part from a dis-assembled printer.
  • Erratic PLA spool feed. Viv rebuilt our wooded spooler, and the PLA now runs more consistently off it. It is still not perfect, so it is still risky to leave the printer unsupervised to do a big print job, but it is reasonably workable for now.
  • Poor adhesion and poor PLA feed. We have played with temperature settings, and also cleaned out the hot-end, and replaced its hob bolt.
  • Off-square x-axis belt. Following the replacement of the broken idler pulley, the replacement was reworked so the belt is parallel to the x-axis frame
  • Heater not powering on consistently: Traced to loose wiring connections, mainly at the original hot-end. This has been fixed.
  • Loose wiring and also a dry solder joint on the Sanguinololu controller board.
  • Cracked x-axis drive pulley. The root cause was the x-axis motor spindle having no flat “key” for the pulley screw to bite into, so the screw was overtightened and eventually the pulley shank split. This caused slip in mainly one direction, resulting in a “leaning tower” effect on print jobs.
Mega Mindy (Reprap #2 aka “The Big Pink”)

Construction began on Wednesday 18th July, after most of the parts required were laid out at the Space.

It was suggested, discussed, and agreed on night to increase its base dimensions, ie the triangular frame,
from the standard Prusa 370mm, by cutting the 1m * 8mm stainless steel rods in half, ie to 498mm. The rest of the framing and smooth rods will be scaled up in synch. This should allow us to print bigger objects: 33% bigger in any dimension, or 2.5 times as large in mass/volume.

We are still missing about a dozen printable parts and will need to get more pink PLA for this.

Vader (Reprap #3 – Grey and black)

This printer is Steve Daltons, but it is being built slowly and steadily as a group effort so far. Construction began late June. So far at least six members have spent time in its construction, with much communication occurring both onsite and on our mailing list, to ensure that this printer is well built.

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