Designing the Cabinet

I had a few design goals:

1. Firstly, I wanted to use a 27" monitor, not the "full-size" 39/40" monitors that will fit in a standard Williams ("WPC") cabinet with an inside width of 20.5" (521mm). This desire stemmed from a) the Wife Approval Factor; b) not being 100% sure, that once built, I would continue to want to play pinball for the long-term and c) being an expat, having to think about the inevitability of moving home one day and not wanting the hassle of moving a 200kg pinball cabinet (and also, the uncertainty of not knowing what house we'd move to and whether it would have room for a full-size pinball machine).
2. Secondly, apart from the different scale, I wanted the finished product to look just like a real cabinet, including legs, buttons etc
3. I wanted an apron at the rear to allow me (eventually) to include flashers or an LCD matrix
4. I wanted a real analogue plunger, so needed to make sure the playfield monitor didn't get in the way of the plunger (or vice versa)
5. I wanted to use rabbet joints, rather than just gluing panels of plywood together edge-to-edge
6. Because I'm using a relatively small and light monitor, I decided not to install a clever playfield monitor hinging mechanism and instead simply lift it out when required. I also decided not to bother with a folding backbox because everything's small enough and light enough to be lifted around by hand.
7. Because I have small children who go to bed early, my pinball "play time" will mostly be in the evenings after they're in bed. This means I can't have a loud clanging pinball machine - or at least, I have to be able to turn the volume down. So I wanted built-in volume switches in the cabinet to be able to turn things down at night
8. I wanted to be able to connect a keyboard and mouse, and connect to the internet (my chosen motherboard had no WiFi) so I needed to have a USB and ethernet socket from the PC exposed to the outside of the cabinet
9. On the topic of internet, I chose to have a machine that is largely not connected to the internet - once everything was installed and running, I wanted to disconnect it and keep it standalone. Not least to avoid unwanted Windows updates from breaking something. New and updated pinball tables will have to be imported using a USB stick

A lot of the design challenges I've had stem from my decision to build a smaller-sized cabinet. The Pinscape guide is all based on full-size dimensions and the vast majority of people who have built a cabinet have built a full-size (or even larger widebody) cabinet, so much of the information about what works, what fits etc is not suitable for a smaller cabinet (or at least, it might be, but it's hard to know).

A couple of things I didn't try to design up front, but rather left aside, to figure out once the cabinet was completed:

1. The front apron / lockdown bar - style, material, dimensions
2. The side rails and protective glass
3. Any lights/flashers/strobes, or LED lighting (under-cabinet or along the side rails)
4. Cabinet artwork
5. The DMD screen

For the apron, it was apparent from my dimensions (see below) that there would be a considerable gap at the front of the cabinet - partly this was to allow the monitor to clear the plunger and partly this was to avoid the backbox being too close to the player - as this is a scaled-down model, the backbox is proportionately lower, and if it was also brought too close to the player, than there would be too much of an angular difference between the playfield and the backbox / DMD which I thought would be uncomfortable. However, I wasn't sure quite how to fill in that gap at the front of the cabinet - perhaps with another piece of plywood, or potentially, with a custom lockdown bar. So I decided to leave this decision until after the build was otherwise complete so I could get a feel for what would work and what wouldn't.

For the side rails and glass, my hesitation stemmed partly from the fact that I wasn't sure if I would be able to get a custom piece of tempered glass. Given where I live, "custom" anything is pretty hard to get unless you speak Urdu/Hindi or Arabic. Which I don't. Plus I wasn't sure if playfield glass would be needed anyway. And the side rails (and front lockdown) are designed to hold the playfield glass securely in place. So no playfield glass = no immediate need for side rails or lockdown bar.

For the lighting, this was really a case of "the more stuff I throw into this, the longer it's going to take to make" and I want to start playing pinball sooner rather than later. Flashy lights are nice, but not essential, and easily something I can add at a later date if I still feel like adding them. Similar logic applies to cabinet artwork - I think I'll probably design some vinyl decals, but to do that I need to learn how to use Illustrator, and then find somewhere here that will print them. Nice to have, and probably a good next project once I've got the machine up and running

For the DMD screen, I have an old iPad lying around that will fit, but I'm not convinced as I would need to swipe it "on" every time I started the pinball machine. So I'll wait until everything else is done and then see if it works or if a proper LCD is needed instead.

Process

I started with the standard Williams ("WPC") dimensions described in the Pinscape guide. Knowing that I only wanted to use a 27" monitor, the next step was to determine a scaling factor to use, to shrink all the dimensions down so that my 27" monitor would fit snugly. I identified the monitor I wanted to use and got its dimensions: 614mm wide by 365mm high. That 365mm now provided me with the interior width of the cabinet: I added 10mm to allow for error and also to allow me to get a finger down the side of the monitor in order to lift it out if needed, thus ending up with an internal cabinet width of 375mm.

I then found a scaling factor that I could apply to the Pinscape dimensions to bring everything down to scale: this factor was 0.74 - in other words, if I multiplied all the Pinscape dimensions by 0.74 I end up with a cabinet that is the right width and depth for my 27" monitor. Then I built a simple spreadsheet that takes all the Pinscape measurements for each part of the cabinet and simply scales them down to my needs (and also converts everything to mm because I don't use or really understand inches). Here's an example for the cabinet side panels:

In the above you can see that I've added a mm to the depth to allow for the final panel to be sanded down to fit flush, as recommended by Pinscape. In this example you can see that I also need to adjust the Pinscape measurements for the rabbet joints that I incorporated. Various approaches to joinery are given in the Pinscape guide. I picked the double rabbet because I have zero carpentry experience and these looked considerably easier than the alternative options. The Pinscape base dimensions assume no joints, so I had to remove widths here and there to allow everything to slot together with the rabbet joints. Because I lacked faith in my carpentry maths, I also built a complete replica of the cabinet in Sketchup (on which more below) to make sure that everything fitted together properly before I actually committed to cutting plywood in real life.

Finally, I allowed a couple of mm for builder-error in a few places: hence the additional mm adjustment which I intended to sand off once the cabinet was assembled. Because I didn't want these visible in Sketchup, I needed a second set of dimensions for the Sketchup model (the green row).

Once I had all the cabinet parts re-sized, I could then determine what width the backbox would be, which in turn informed me what size backbox monitor I needed (something less than 545mm, so around a 22" monitor) and similar for the DMD (something around 230mm, or about a 10" diagonal screen).

Routing and jointing

Once the panel dimensions were set, I created a new sheet to calculate all the various rabbet joints and holes (button holes, fan holes, speaker holes). Whilst I resized the cabinet panel sizes using the 0.74 adjustment, I couldn't rescale all the button holes and positions because a) I am using standard buttons and b) the standard positions are designed to work well with full-size humans, of which I am one: there was no point re-positioning all buttons by 0.74 because then they wouldn't fit my fingers. Here's an example of the calculations for the cabinet sides and front panel:

However, things like the speaker holes and DMD cutout dimensions in the DMD panel did have to be re-calculated: my DMD panel will be a custom width, and much narrower than a full-size, so I had to make sure that I could fit the speakers in, that they wouldn't get in the way of the brackets I was going to use to mount the panel to the backbox, that the DMD cutout would be big enough to actually be visible and importantly, that it wouldn't be so small that I couldn't find an LCD panel that would fit etc.

Sketchup

As a complete beginner to carpentry - indeed, to designing 3D objects of any sort - it seemed like a really good idea to "build" my cabinet in software, before I tried to build it in real life. There are a few options for 3D design software, but the one I settled on was Sketchup. It has a free online version that seemed to allow me to do everything I needed, and the learning curve wasn't too shallow (yes, shallow, because most people plot time on the x-axis).

So I took my dimensions spreadsheet and slowly "built" the cabinet in Sketchup. By doing this I could determine that the measurements (and particularly, the adjustments I made for the rabbet joints) would assemble to a 3D object which actually fit together without gaps or overlaps.

Test fitting components

Once built in Sketchup, I was then able to "test fit" various PC options inside the cabinet. Again, the smaller size of this build meant that internal space in the cabinet is limited - standard builds seem to have plenty of space for pretty much anything and everything, but this 3/4 size cabinet was going to be more of a challange. I already had some PC components to hand (CPU, memory) so decided to go for a no-case build, with the motherboard mounted (through standoffs) to a small piece of 6mm plywood. But I wasn't sure if I should go for an ITX, mini-ATX or ATX motherboard, and I wasn't sure if a standard sized GPU would fit. With Sketchup, I could quickly mock-up small boxes of the same size as these different components and put them inside the cabinet to see what fit, and in what orientation. This led me to a standard ATX motherboard size, but with a) smaller 2-fan GPU and b) SFX power supplies, which take up considerably less space (and have much shorter cables) than the standard size.

Cutting plan

Again in Sketchup I created a copy "off to the right" of my cabinet and collapsed all the panels back down into a single horizontal plane, then jiggled them around inside a simple rectangle that was exactly the size of a standard piece of plywood (1219mm by 2439mm). This allowed me to come up with a way to cut down the standard piece of plywood into all the various shapes I'd need. In a standard-sized build, there's barely enough plywood to make all the parts so this is quite a tricky job. For my 3/4 build, there was plenty of spare plywood left over (sadly, not enough to account for the massive screw-up I made on day 1 of cutting, but more on that later).

Parts

As described above, Sketchup allowed me to figure out what parts would fit in my cabinet even before I built it. This allowed me to pick a backglass monitor that I knew would fit. It also allowed me to pick the following parts, with reassurance that they'd actually fit:

• Backglass speakers - I went for 4" car speakers because I knew they'd fit even in my reduced-size backbox. And a subwoofer - I went for a 6" car sub and could test in Sketchup that it would fit, and where it would best be placed
• A plunger - again, I built a very crude plunger in Sketchup (basically, a cylinder of the right diameter and length) and made sure that it wouldn't hit the playfield monitor or the right-hand flipper and MagnaSave buttons
• Flipper buttons and leaf switches - Sketchup allowed me to tweak playfield monitor height and front panel buttons so that nothing clashed with anything else. I actually tweaked the Pinscape guide for the front panel button positions as I wanted more space on the sides for my flipper button assemblies. I also could tell that there would be enough room for the longer 1 3/8" flipper buttons with the VirtuaPin leaf switch assemblies.

I built a parts list on a second sheet of my spreadsheet, listing options, prices and dimensions. This turned out to be pretty important because there are a lot of parts in a pinball cabinet, and keeping track of what I needed, had, had ordered, was being delivered or was still not ordered was a not-insignificant logistical challenge. Basically, this Excel sheet became my virtual quartermaster.

Concept test

I couldn't resist buying the PC parts and monitors, getting Windows installed and testing it, long before I started building the cabinet.

Next

With my design in place, the building process could commence.