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Printing tips & instructions

Ben Gruver edited this page Feb 19, 2019 · 2 revisions

Note: I use Slic3r (prusa edition) pretty much exclusively, so you may need to translate my recommendations into the appropriate dialect that your slicer of choice speaks :)

Filament choice

For the clusters and keys, you want as opaque of a material as you can get. Try printing a small 2mm thick solid sheet, and hold a flashlight up to the back. Ideally, you won't see any light leakage through the print at all. I tried a few different filaments that I had on hand, and by far the most opaque was some 5% copper filled PLA by Gizmo Dorks.

However, PLA does not work well for the 3d printed "PCBs", since PLA has such a poor heat resistance, and it's too brittle and prone to breaking for the ball-head screws. In both cases, I recommend polycarbonate, although ABS may work as well. I used Polymaker's PC-max filament for both.

Clusters

The clusters should be printed in the opaque PLA at a fairly fine layer height, mostly due to the threaded sections that the ball-socket cap screws onto. I recommend .1mm.

If you run into issues with the corners raising up during the print, try changing the infill angle to 0 or 90 degrees, instead of the 45 degree default. I had some issues with this even with the PLA strangely. But with the infill being parallel to the sides, it spreads the "pull" due to shrinkage across the edges better, and doesn't have that concentration of stress at the 2 opposite corners that are in line with the 45 degree infill.

Keys

The keys should be printed in the opaque PLA, and generally don't need any special consideration to print. One exception is the center "down" key, which should be printed with a fine layer height (.1mm). This is so that the shaft is as smooth as possible, to reduce the friction between the shaft and its hole in the cluster, and to help prevent it from binding and getting stuck down.

Also note that all of the thumb keys except the "down" key need to be printed with supports enabled.

Ball-head screws

These are the trickiest to print, due to the tall and narrow geometry, with very little surface area on the bed. They should be printed with the PC-max filament at .1 layer height with 100% infill and a raft. I also tweaked the default pcmax profile a bit - I enabled the cooling fan at 20% and reduced the heat bed temp to 100, since my bed wasn't able to reliably get up to the 115 of the default print profile.

That neck area between the threads and the ball head is where these tend to break, so I also tweak the printing parameters in that area as well, although this is probably optional :). I make the external perimeter nice and thick (.8mm extrusion width), for extra strength and layer adhesion. I also use a concentric infill for this area. Or you can just crank up the number of perimeters. The idea being that a circle of infill should be stronger than some straight lines or whatever.

If you run into problems with the screws detaching from the raft, or with the raft detaching from the bed during the print, I recommend changing the extrusion width for the first layer of either or both to .8mm. This ensures a nice "squished" first layer, with the highest chance of staying adhered.

Ball socket caps and screw bases

These aren't too bad to print. Since they're both threaded, you need to print at a fine layer height - the usual .1mm is perfect. The filament choice here isn't important, I just used the same PLA as I did for the clusters and keys.

PCBs

These should be printed in PC-Max, with 0 or 90 degree infill to reduce the chance of corners pulling up. I also print the first layer with .8mm extrusion width, to help ensure good adhesion.

Handrests

The handrests should be printed with supports enabled, but only the front edge of the opening in the middle needs to be supported, the rest of that void can be bridged over, so you can enable the "don't support bridges" option if it isn't already enabled.

If you want a fairly smooth surface, I recommend .1mm, but they're perfectly fine even at .35mm. If you use .1mm layer height, I recommend bumping up the "combine infill every" setting to 3, which helps keep the print time in check. This allows the perimeters to be printed at .1mm, while using .3mm for the majority of the infill.

The material isn't terribly important. I used a copper colored PETG filament that looks similar, but somewhat better than the copper-filled PLA, if less opaque :)

Printed part BOM

Cluster parts

  • 8x cluster.stl
  • 8x cluster_pcb.stl
  • 24x short_side_key.stl
  • 8x long_side_key.stl
  • 8x center_key.stl

Thumb cluster parts

  • 1x right_thumb_cluster.stl
  • 1x left_thumb_cluster.stl
  • 1x right_thumb_cluster_pcb.stl
  • 1x left_thumb_cluster_pcb.stl
  • 2x inner_thumb_key.stl
  • 2x thumb_down_key.stl
  • 2x outer_lower_thumb_key.stl
  • 2x outer_upper_thumb_key.stl
  • 1x right_thumb_mode_key.stl
  • 1x left_thumb_mode_key.stl

Central parts

  • 2x central_pcb.stl
  • 2x central_pcb_tray.stl
  • 1x left_handrest.stl
  • 1x right_handrest.stl

Standoffs

You can mix and match the heights to find the perfect height/angle for your hand, so it's good to print a surplus of the various sizes to have enough to experiment with. Here are some recommended print counts, based on how I have mine set up, with some extra of each.

  • 30x ballscrew_cap.stl
  • 30x ballscrew_base_tall.stl
  • 16x ballscrew_base_short.stl
  • 6x ballscrew_base_tiny.stl
  • 30x ballscrew_tall.stl
  • 16x ballscrew_short.stl
  • 6x ballscrew_tiny.stl