Illuminated Space Shuttle Pinball Machine Toy

Making a replacement toy for the Space Shuttle Pinball Machine

The central toy on the Space Shuttle Pinball playfield is often beaten up and broken.  I have repaired several of these, but I have always wanted to modify one to light up.  Despite the white color, the plastic in the original toy is completely opaque, and therefore incompatible with this mod.  In 2008, Bob from Phoenix wrote me that he had started the process of vacuum forming them, and I assisted him as well as I could.  This write-up shows how the custom toy was made.

toy as found
Example of an original Shuttle toy with typical breakage.

The master form for the Shuttle toy created by Bob.  It is not an exact
replica, but quite close.

The vacuum forming table.  Essentially a box built with 2x6s
with holes in the top for air flow.

The underside of the box.  The vacuum is a 10 gallon shop vac with the filter
removed for maximum flow.

The master mold on top of the vacuum forming table.

The procedure for vacuum forming:
  1. Suspend the sheet of PETG in your oven (set to 325F) until it sags (about 3").
  2. Quickly put the soft plastic over the form
  3. Hit the vacuum to mold the plastic.
  4. Once cool, remove and trim the edges.
The plastic is 1/16" (0.06") thick PETG from Professional Plastics in Phoenix, AZ.

A freshly formed plastic sheet.

The edges of the toy trimmed off.

The toy painted white and ready for decals.

Bob sent me two of his creations, and the rest of these images were shot by me.

The first technical hurdle was applying a translucent coating onto the inside of the clear plastic.  I experimented with various viscosities, and settled on a four to one ratio of water and white acrylic paint (more water than paint).  Some Acrylic Flow Improver (by Winsor & Newton) was added to ensure that the paint particles stayed suspended.

The paint was applied by pouring some into the form, and then swishing it around.  I then let it drain and dry.  This was then repeated a total of five times to build a thin even coat of paint.  The result looked quite good except one could still see some unevenness when backlit.  However since the real Shuttle has blemishes too, I was not too concerned about it.  One important issue is that the coating is very soft and can easily be scratched.  So I always had to handle the form very carefully.

The vacuum formed toy after application of the translucent coating
on the inside.

The toy cut from the full sheet.  The applied paint looks very even, although
slight variations can be seen when backlit.

As an afterthought, I figured out a way to replicate the Main Engine nozzles
by using red star posts.

Photo with the real thing showing the main engine nozzles.
This was shot during the preparation of STS-125.
Click here for my involvement with this mission.

The finished upper form.

In my restorations of the standard Shuttle toy, I fasten an anodized aluminum sheet to the bottom of the unit for stiffness and stability.  This platform has always given me the idea of one day mounting LEDs on it to light up the toy from below.  However due to the original plastic's opacity, this would only be possible with a custom molded form. 

I first cut an aluminum sheet to cover the bottom completely.  The idea then was to nestle the plate into the bottom of the plastic (just like I do with the original toy), but I soon realized that the coating I had previously applied was too soft.  Eventually, the white would be scratched off the bottom edge, and it would not look very good. 

I changed the plan to have the aluminum extend all the way around, and bent small tabs to hold the outline of the toy.  This prevented all contact with the soft acrylic paint.  The aluminum sheet was also a good substrate to mount the switch that is activated when the ball ascends the ramp.

Photo of the bottom of the upper form, and the lower platform that holds the micro
switch and LEDs.

For the LEDs, I selected white low-profile ones that had a small hemi-spherical focusing lens.  I filed the lens flat, and the resulting pattern was very even.  I lined four of them up along the main long axis of the toy.  I then selected two high-brightness sharp focus units and laid them down flat to light up the wings.  This produces a long white path of light, which would hopefully shoot its way into the narrow and flat wings.

I used white hardware as much as possible.  This included white wires, and a white microswitch.  The microswitch is put on the starboard side so that its shadow would be cast on the side of the shuttle toy facing away from the player.  That strategy paid off extremely well as you will see later.

Closeup of the switch assembly.  I bent a wire to form a rectangle under the toy,
and the trip lever then hits the microswitch lever.

The white LEDs are connected to the GI circuit.  With a meter, I measured that the GI circuit is at 5.6Vac on my machine.  I then set up a 12V wall-wart transformer with a variable transformer dialed to the same voltage.  I could now test the white LEDs from my workbench.

The LEDs have a forward voltage of about 4V.  I placed the four middle ones in parallel, back to back.   Thus two conduct on each half wave of the GI waveform.  This is then in series with a 43 ohm 1/4 W resistor.  The steady state current is about 60mA, so each LED runs at 15mA rms.  The two narrow beamed LEDs are also back-back, and have their own 43 ohm resistor in series with them.  They consume 20mA, leading to a total load on the GI of 80mA (AC rms).  This is well below a single #44 bulb.

Close-up of the middle part of the toy.  One can see the two side-firing
narrow focused LEDs that light up the wings.  Also note the three
red LEDs in the back.

One problem that I only solved at the end was what to do about the Main Engines.  These are of course a very prominent part of the Shuttle.  My first idea was to simply have red LEDs fire upwards to cause the OMS (Orbital Maneuvering System) pods to glow and flash (these are the round bulbous parts in the back of the Shuttle).  However, I did not like this idea as an exhaust plume would look much better.  I then thought of how I could produce this plume, and hit on the idea of fastening red star posts to the back to form the nozzles of the main engines.  I could then simply put some bright red LEDs in the back to light them up.  These LEDs had to fire upwards into the star post for maximum effect, so embedding them into the star posts would not be preferred.

Close-up of the aft section.  The LEDs are simply hot glued to the metal
substrate.  The aluminum is anodized and forms a tough insulating

There are three ways to illuminate the red LEDs.  In the first, I could connect it to the flash bulb circuit.  These light up infrequently.  A better circuit are the two lamps on the lamp matrix (#39 and #40).  These flicker constantly during attract mode and game play.  In addition, #39 is very easy to reach on the playfield.  The positive line (Yellow-Green) is used by the '1000', '2000', etc lights, and the negative line (Red-Violet) is used by the 'A' light.  Both of these lines are within inches of the pass-through hole for the microswitch cable.

The red LEDs are wired in series, with a blocking diode, and a 43 ohm resistor in series.  This produces a bright red flicker effect in the exhaust nozzles.  It looks quite good.

Once that was done, I printed a set of graphics onto clear adhesive polyester, and applied that to the upper form as a final step.

The finished toy.  The illumination is
very even, and the red nozzles flicker the same way the lights
do on the exhaust plume on the backglass.

Shot with three Shuttle toys.  Repaired unit prepared for sale (left),
unit that lights up internally (middle), and original unit for this machine (right). 
Note the signed plastic in the lower left.  It has been signed by
the crew of STS-125.

In conclusion, I am quite happy with the result, but I will see if any adjustments need to be made with game play over the weeks ahead.  One unforeseen effect is that the hole cut into the bottom plate to allow the trip wire to pass allows quite a bit of light onto the ramp.  This lights up the very dark ramp entrance.

If you enjoyed this mod, you may also want to checkout
others I have done with similar complexity:
Project Log
  • March 2009 - Bob develops the process of vacuum forming the Shuttle toy.
  • July 2009 - Using the vacuum formed sheet from Bob, I create the custom toy for my machine.

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