Printer End Caps

After printing a dice, I decided to print something more difficult than a cube, but also useful. The aluminum extrusions have cut ends that are sharp, so I designed an end cap. This object had a number of firsts for me, being the first object I designed myself with AutoCAD, to have thin structural details, and to have custom designed supports.

These sharp ends have drawn a little blood as I worked around the printer

An end cap designed to cover the end, fitting into the extrusion slots

I knew I wanted the outward facing surface to be very flat, so I printed it on top. The dice prints had shown that I have quite a bit of bottom side bleed-through, which means I need more pigment in the resin. Until pigment comes or I change resins, I'm working around it.

I also knew the dice was a little smaller than designed. The dice were 11.5 mm, when it should have been 12 mm. The MSDS for Makerjuice currently states a shrinkage of 5% (per dimension I believe, not volume). I designed the end cap to be 21 mm, anticipating the shrinkage to result in 20 mm.

The support tabs bent outward due to the top layer shrinking

I learned that the thin tabs that insert into the extrusion bent out as the top layer cured. The first layers of the top layer shrank, moving the top of the thin tabs inward, while the bottom of the thin tabs remained in place. The consequences of this new angle meant the supports act like springs in the extrusion slots, adding friction and preventing the cap from coming out. However, this adds stress on a fragile and thin part. I snapped one tab after inserting the endcap a few times. I'll have to redesign the part with this bending effect of the shrinkage in mind!

Fits!