Adventures in 3D printing Pachinko Pockets

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As part of a customization project that I'm currently working on, I decided I wanted to try my hand at creating my own custom pachinko pockets to replace the little bunnies that once caught the occasional ball at the bottom of my machine. Unfortunately, the bunnies would not fit with my target theme Going for a Japanese Ryuu (dragon) theme on the machine.

Printing the pockets would give me a good idea of what to expect when I go about creating a custom center feature later on for the same machine at a much lower price

In browsing the internet, I came across a clip art image that gave me an idea about what I wanted to do. It's a little Koi fish splashing about in the water; a perfect fit given that the mythology around Asian dragons in general is that they start off as Koi fish. This is the image that I ultimately ended up starting with:

koi-fish.jpg

Nice and round shape that suits a lower pocket for a pachinko machine well. $10 later, I have a vector version of the file that I can work with, and the feel good sensation that comes with supporting an artist.

For the 3D modeling portion, I'm using PTC Creo Elements Direct Modeling Express, a free version of the professional Creo drafting tool that they produce. The program works OK, but ultimately had a number of interface issues that made things take longer than they actually should have. But hey, it's free, accurate for sizing and exports to the format I need for 3d printing, so I'll make do

I loaded up the image in a vector processing tool and cleared out a few of the details. At the scale I was working at, I wouldn't need the bubbles, nor the colour gradations on the scales or waves. It took a few tries to get the overall shape into an outline that I could import into Creo Express for quick and easy extrusion of the details. This ultimately involved ensuring that I exported one cohesive shape through welding/combining/intersecting the various shapes in the EPS file I bought into a DXF file, importing the DXF into PTC Creo Elements Direct Annotation and then copy/pasting the sketch onto a workplane in Modeling. Took me about half a day to figure out the magic combination of actions that would allow me to copy and paste into Creo. (And I'll detail them on my blog when I get to that point to save some of the technical stuff)

A few hours, power outage (lost all my work!), and then 30 minutes later, I had a workable model:

fishpocket.jpg

I kept the scale detail as more of an experiment than anything. I wanted to see just how small of details 3d printing could manage. (Ultimately, these initial prints were more to see if this was viable more than anything else)

I exported the model to STL format and uploaded it to Shapeways for printing. A few revisions had to be made, but eventually I got something that was printable. Placed my order ($6 for the two pockets + Shipping) and in two weeks, I had my pockets.

BRGccEWCIAEWgpz.jpg

New pockets compared to old bunny pocket.

As you can see, the scale details did not come out at all, which means I'll have to revise the design and put the details in in paint rather than in plastic. (I figured as much) The waves had no problem coming out.

The material I used was the Strong, flexible plastic in polished royal blue. The colour itself is very royal blue, so that's fine though the finish is very gritty. It almost feels like a very fine grit sandpaper. It's also very matte, so I may need to look into whether or not I can put a clear coat on this plastic without damaging it.

On reviewing the design I used, I have made the following notes for the "better" print that I'll do when I get my center piece artwork done:

• I used 1mm width on the wall that catches and diverts the ball into the hole in the board. Given the material and general impression of the strength of the material, I probably want to increase the width to 2 or 3mm to ensure it doesn't crack under the constant pummeling of 11mm steel balls
• Holes are lined up perfectly with the holes on my playfield, so my measurements there are good.
• The rails I built in to the inside to divert the ball into the hole were too thin to print. They need to be 1-2mm wide as well.
• I need to reduce the detail on the fish such that the holes/details are similar to the waves.

I'll be doing some additional testing on the material later on in the process, but I figured I'd show off what I had for those who might be looking into 3d printing parts for their machines.