The Modern Firepower Pinball Project - The Cabinet is Nearing Completion

The pinball cabinet has landed!

I’ve been constructing the cabinet by hand over the past month, and just yesterday I installed the cabinet legs for the first time, and the cabinet is finally on the ground.  Now in a very recognizable form, this deceptively simple looking box was one of the most challenging aspects of this project.

To me, the most recognizable feature of a pinball machine is the cabinet.  The classic coffin shape is unmistakable even from a distance, and four years ago it seemed to me they all looked exactly the same. When I started the project, I gave little thought to constructing the pinball cabinet, thinking it is little more than a box with a window on top.

It wasn’t until much later that the cabinet became a design nightmare.

My goals were simple, I wanted to create the modern interpretation of a standard shaped pinball cabinet that could house any normal-sized playfield, and modify it to hold a TV for the backglass.  I was planning on writing a Windows program to be the heart of the pinball machine, and envisioned using a TV for showing artwork and scores while playing, and also for the control panel to configure the game.


My main challenge was that I didn’t have access to a pinball machine to measure the cabinet.  Complicating matters, I foolishly assumed that there was some kind of standard cabinet specification, wonderfully detailed in nerdy schematics.  Google corrected my assumptions:  turns out that there are a lot of cabinet variations and there is no industry standard.  The lack of industry standards has haunted me through the entire project.

Even worse, I was unable to find any decent schematics.  Most of the schematics I found were not standard pinball cabinets, but rather modified designs intended to hold LCD panels for digital pinball games like VirtuaPin.  These measurements were worthless for creating an authentic pinball cabinet.  I also couldn’t find a parts list for all the cabinet hardware I would need.  I had to do a lot of research to come up with a parts list, and even then I’ve missed a few items along the way.  Parts are in the mail as I write this, and I’m sure the last order has not been placed.

The component closest to having a standard size is the playfield; most playfields come in one of two widths and have a common length.   Since the cabinet’s primary purpose is to house the playfield, the playfield’s common sizes leads to cabinets that are roughly similar in size, yet that still doesn’t lead to any real standardization of form factor.  I pressed forward in the belief that as long as the interior dimensions were matched to the playfield dimensions, the cabinet would turn out fine.

Every manufacturer seems to have their own variation of a pinball cabinet, their own ideas on length, width, angles, trim and features.  These ideas have changed over time as well, with each decade bringing new styles of cabinet to market.  It was hard to know where to start and what direction to go in.



Since I wanted to use standard pinball cabinet parts, I decided the best path forward was pick a cabinet style that I liked and that had all the parts available for purchase.  That decision led me to a 90’s era William’s standard width cabinet design.  I then ordered all the Williams parts I could find:  legs and brackets, lock bar and receiver, coin door, side trim, hinges, glass and the plastic channels for the glass.  I also ordered some arcade buttons for the cabinet.

The best schematics I found were for a William’s widebody cabinet provided by ‘macattack’ on the arcadecontrols.com forum.  Unfortunately, macattack had documented the sizes in metric, and these measurements didn’t convert cleanly back to the fractional inches that I’m sure these American produced cabinets were originally spec’d.  Also, several key measurements were missing, such as the cut-outs for the coin door and ball shooter, the positioning of the leg bolt holes and the cabinet slope.  +Ben Heck (one of my heroes) had published some schematics for his pinball designs, and while these were based on real tables, one look at the design showed me he had taken way too many design liberties for me to use his measurements.  Luckily, Ben did show that the cabinet is sloped 3.5 degrees forward, a key measurement I needed, and the slope is accomplished by mounting the front legs higher on the cabinet than the rear legs.

My scribbled measurements... at least I kept notes.

With everything in hand, I reverse engineered the cabinet design.  I had to look at hundreds of pictures to determine what features in the schematics to trust, and I carefully measured and test fit every piece of cabinet hardware I had purchased.  I worked methodically, allowing each known measurement to lead to the next.

I didn't notice until after I installed the lockbar receiver, but there are two metal tabs that align with the top edge of the wood panel.  This seems to be a feature to help in proper installation. My installation method was within a millimeter of perfectly flush on the metal tabs.  I still prefer my method, as it ensures alignment left to right.

For example, before I cut the side panels out of the 3/4" plywood, I held the various trim pieces and the glass panel against my penciled cut lines to ensure the dimensions were compatible; and after I had cut and assembled the sides of the cabinet, I was able to determine the proper installation of the lockbar receiver simply by attaching the lockbar, holding the assembly in place, and then marking the screw holes.

The plastic channel for the glass panel, which installs like a T-molding.  To install the channel, you need to cut a slot on the top edge of the cabinet side walls.  I couldn't find the cutter size mentioned anywhere on the web, so I measured the plastic channel and took a chance and luckily I got it right.  I used a 3/32" slot cutter router bit.

As I proceeded, I found that each piece only fit correctly one way, and so as long as I test fit and measured carefully, the parts basically defined the cabinet.  Form follows predefined form.

The rear legs are installed low with only a small gap at the bottom of the bracket.

Installing the legs was very daunting, since I had limited measurements to go by.  I finally concluded that the proper method was to install the rear legs as low on the cabinet as possible, limited by the bottom panel of the cabinet, and the front legs are installed 3 1/8” inches higher, which on a 51.5” length cabinet provides the proper 3.5 degree slope to the cabinet.  High school trigonometry saves me again.

The front legs are installed 3 1/8" higher. Notice that the bracket is flipped to put the bolts at the top.

Just like Ben Heck, I took a few liberties in the design to make it fit my goals.  The backbox is not a standard size, it is about 1 inch wider and has been designed to hold a decased 32” TV.  The arcade buttons I chose to use for flipper buttons are much deeper than normal leaf switch flipper buttons, and had I installed them in the typical location the buttons would have obstructed the playfield inside the cabinet.  The solution was to install the flipperbuttons about an inch lower in a position that was still comfortable to reach, and within a fraction of an inch of hitting the playfield.

Notice the large slot on the inside of the backbox.  The LCD TV slides into this slot.

I also skipped the typical ventilation holes on the back side of the cabinet , and instead I am attempting to control air flow from the bottom front of the cab, up through ports into the backbox, and then out the back at the very top.  The airflow path is similar to a modern computer case design.  I’m hoping a convection current will create a constant airflow to keep all components cooler, and I’m also expecting my choice of components to run much cooler than a normal pinball machine would run, minimizing the need for cooling.

Three 4" holes for cabling and airflow between the cabinet and the backbox.

I've been taking notes and recording my measurements, currently just chicken-scratch on paper.  I'm contemplating whether to share the dimensions and schematics, because like so many before me, the cabinet I have designed is not an original.  I'd be curious to see this cabinet side by side with an original pinball cabinet of the same vintage, just to see how close I came to an original William's cabinet.

I still have a few challenges left to master before the cabinet is complete.  I haven’t been able to mount the backbox hinges to the cabinet, as I seem to be missing some spacers that would prevent the hinges from rubbing on the cabinet artwork.  I’m waiting on some plastic bushings to be delivered that I think are supposed to be used when mounting the backbox hinges to the cabinet.  Hope I'm right.

I need to install playfield support strips inside the cabinet for the playfield to rest on, and these need to be positioned to slope the playfield at 6.5 degrees.  Unfortunately, when you put a playfield in the cabinet to measure the angle, you can no longer access the underside to install the support strips.  I will cut a big hole in a test playfield so that I can I can accurately slope the playfield while installed and still have access to mount the playfield support strips.

I expect the biggest challenge will be installing the ball shooter – this is the only component mounted to the cabinet that interacts with the playfield.  I theorize that if the angle isn’t correct you will either launch the pinball into the glass, or not have enough power to get the pinball up the ramp.  I’ve found absolutely no measurements that detail how to install it correctly, so like every other component I plan to reverse engineer the installation location.  After the playfield is installed I will take a wooden dowel the same size as a pinball, place it on the ramp, and slide it down until it makes contact with the front panel of the cabinet.  That will show me the correct location for the ball shooter.

After everything is installed and tested in the cabinet, if I can tear myself away from playing pinball, I plan to disassemble and paint the cabinet.