Summary

This small tabletop bowling game was made for my children and friends birthday party. Make a set of 5 or 10 pins, add a standard marble (glass preferable) and play. No rental shoes required.

Instructions

This was fabricated on a MakerBot Replicator (2012 model) Dual, using the standard MBI Black and White ABS 1.80mm filament, and with MakerWare 2.01 on medium quality with 2 shells, 15% infill. ABS extrusion temperature was set to 230C and HBP was set to 110C. A layer of ABSynthe (scrap ABS plus acetone) was spread on the kapton tape to improve adhesion.

To get the proper dual extrusion I opened the white STL first, and then added the red/black STL layer second. On my system the black spool was on the right extruder, and the white spool on the left, so I had to set the colors in the MakerWare preferences, and then select the white objects and change them from the default right extruder to the correct left extruder.

When building an array of pins, you will need to use a raft, otherwise near the top of the pin structure (just below the second color) the pins will get knocked/dragged down by any ooze from the secondary extruder head (see the third image for what an afternoon of printing will give you without a raft). MakerWare will NOT generate a raft when dual-strusion is required (gahh!). To fix this I manually created a 0.54mm flat surface, added it to the THING in MakerWare, and moved the pin array "up" by 0.54mm (make sure to select both the white and the black/red pieces of the pin when moving it vertically). Arrays can be loose, gridded, staggered or maximally packed for density.

NOTE: If you print a single pin on a MakerBot Replicator Dual, you will see the ooze effect from the inactive toolhead brushing the print during the build at every-other layer increment due to the GCODE tool-change command. The only way to get a really clean print as far as I can tell is to watch the print like a hawk and use a knife to scrape off the ooze from the inactive extruder. Print time for a single pin with the settings above was 22m on a pre-heated system.

Modeling:

To create the pin model in Rhino (OS X), I first created the contour using "curve through points". To find the points for the curve I created simple boxes representing the outer dimensions of the pin, and then created POINT objects at the verticies. Then select curve through point and use the vertex points for the outer curve (bottom to mid-point) and separate curve for the mid-point through to top (from just below the black/red band up to the top of the pin). Once a full profile curve is available, to create a water-tight solid I use "revolve around axis". Once this is complete to add the color band in the middle of the pin I created two "surface from planar curves", one at the bottom of the black/red band, and one at the top of the band. Then Boolean split using the surfaces just created as the cutting objects. This leaves us with 3 distinct watertight solids, the base, the colored band, and the top. Export the two white objects into one file, and the black/red band into the other file.

Tabletop marble bowling pin