3D Printing Leg Levelers for a Pinball Machine Trophy

A 3D model of a leg leveler designed in SketchUp. The 3D printed leg leveler on the bed of a MakerBot Replicator 2 3D printer. The 3D printed leg leveler fitted into the end of a pinball trophy leg. The FSPA pinball machine trophy with 3D printed leg levelers.

I designed and 3D printed leg levelers for my FSPA pinball machine trophy. Click photo to enlarge.

The Free State Pinball Association awards miniature pinball machine trophies to league winners. Their trophies include many details such as flipper buttons and coin doors, but they have no leg levelers. I designed leg levelers for my trophy and 3D printed them at a local maker space.

Free State Pinball Association Trophies

Back Alley Creations designed and built the trophies awarded by FSPA. Each trophy resembles a modern pinball machine, with a body, hinged backbox, coin door, plunger, flipper buttons, and legs. A trophy is about 5½ inches long and 8 inches high. Laser engraved plates replace the backglass and playfield. They are surprisingly heavy at about 26 ounces.

Through a combination of luck and slowly improving skill, I won an FSPA trophy last summer in the B division at Mighty Mike's in Sterling, Virginia. The trophy looked great on my shelf, but was missing something: leg levelers. The legs made of square brass tubing were simply cut off at the bottom and perfectly aligned to provide rock-steady support to the tiny game.

Measuring the Real World

I measured a leg and leveler from Surf Champ, the newest game I own. The leg leveler was screwed into the leg's square base, which was 1 3/4 inches on each side. The diameter of the leg leveler was roughly the same. The leg leveler bolt was 5/8 inches in diameter.

Using the best Harbor Freight digital micrometer that $12.95 can buy, I measured the inside and outside of the trophy legs three times each and averaged the readings. The square trophy legs were 5.6 mm inside and 6.6 mm outside.

Designing a 3D Model

I chose the free 3D drawing program SketchUp Make to design my miniature leg leveler. I watched a dozen tutorial videos on the SketchUp web site and practiced making the example models myself. Now I know enough to be dangerous.

SketchUp's drawing tools seem to work best on models ranging in size from tabletop to an entire building. My leg leveler model was much smaller, so I multiplied my dimensions by 100 to work in SketchUp. The leg leveler diameter of 1 3/4 inches is 44.45 mm, so I modeled it as 4445 mm. (I reduced that slightly so the drawing radius was 2222 mm in the model.)

The model comprises three components:

Leg Leveler
I modeled the profile by eye with a few arcs. Then I used the Follow Me tool to rotate the profile through 360 degrees.
Bolt
I drew a 5/8 inch diameter circle (1588 mm in the model). Then I pulled it up to an appropriate height to make a cylinder.
Leg Plug
I drew a 4444 mm square and pulled it up slightly to form the lip to hold the leg. I used the offset tool to make a smaller square on top and pulled that up to form the plug to fit inside the leg. I scaled the top to make it slightly smaller, giving a taper to the plug.

The first screenshot below shows the finished leg leveler model.

3D Printing the Model

Cortona Academy of Science, Technology & the Arts in Herndon, Virginia hosts the Reverse Space makerspace. Local makers gather each Thursday to work on their projects, to use any of the dozen 3D printers, and to socialize. Members and guests are welcomed by Karl Strauchs, who enthusiastically explains how to use all of the complex technology.

During my second visit to Reverse Space, Strauchs walked me through the steps to 3D print my model on a MakerBot Replicator 2. First I downloaded a plug-in for Sketchup to export my model in STL format, which is used by many 3D printers and tools.

Next, I imported my model into the MakerBot software. This program showed how my model would look in the 3D printer: much too large. Recall that my model was 100 times the actual leg leveler size, which was many times larger than the size needed for the trophy. The MakerBot software let me scale my model down to 6.6 mm to match the trophy leg. Now my model looked tiny compared with the printer.

The MakerBot software examined my model and planned a path for print head to create a disk, a cylinder, and two boxes. I selected the "raft" option to print a stable base under my model. Strauchs checked my progress and adjusted the print speed to accommodate the tiny model. The program rendered the 3D printer instructions to a file on an SD memory card.

I inserted the memory card into the Replicator 2 and pressed Print. The machine heated its extruder until it reached 220 degrees Fahrenheit. Then it began to move. First it demonstrated its readiness by depositing a line of plastic along the front of the printer bed. It moved the print head to the center of the machine and quickly laid down the raft—a circular base for the model. Then it outlined the bottom of the leg leveler and filled it in with a back and forth motion. The bed descended slightly and the printer added another layer to the model. Soon it finished the leg leveler and began to work its way up the bolt.

Trouble began when the printer outlined the leg plug. There was no supporting structure underneath, so the plastic squirted out to form what looked like a pile of spaghetti. Eventually the coils of plastic provided enough support to complete the leg plug, but this model was doomed.

Strauchs showed me how to add supports with the MakerBot software. This second model was better, but I could not remove the supports from my tiny model. Still, it let me check how the plug fit into the leg.

Back to the Drawing Board

After some Internet research, I redesigned my model to avoid unsupported overhangs. I turned the entire model upside down so the leg plug would print first. I widened the bolt to add strength. I introduced a taper from the bolt to the leg leveler. It may not look prototypical, but I hoped it would print.

I returned to Reverse Space the next week to try my new model. The first print was successful, so I printed three more leg levelers. A little dab of glue secured them in the trophy legs. Next time I'll print some more with gray plastic instead of black.

With a print time of five minutes a piece, 3D printing is not suitable for mass producing tiny leg levelers. I needed only four leg levelers, so 3D printing was the right tool for me. In just two evenings, I was able to experiment with different designs and printer settings until I was satisfied the the results.

My leg leveler model can be downloaded from the SketchUp 3D Warehouse. You can print it yourself in a makerspace near you or modify it to meet your own needs.

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