Playfield

Playfield :: Fabrication :: Slots

If you are going to CNC your playfield, that’s great. However, most people don’t have free access to a CNC machine, and paying someone to do the job for a one-off project may not be cost effective. So, for most of the blog, I will consider that the fabrication sections are going to be done by hand…

The second-most-difficult feature of the Playfield to create by hand is the Switch Slot (the most difficult being an Arrow Lens).  The Playfield Switch is obviously one of the most important hardware features of a Pinball Machine, since the game is essentially a continuous electro-mechanical interaction, where the Pinball activates a Switch, which in turn activates a Solenoid, which in turn impacts the Pinball, and so on, and so on.

We start with a full-size 1:1 printout of our Playfield CAD drawing, but in this example I’m just focusing on the section where the Switch Slot will be. Spot-drilling all of the features at the same time with a full-size drawing will guaranty that holes are placed correctly relative to each other. Here is the Slot creation process in detail from start to finish.

Step 1:

Spot drill both ends of the slot using a 1:1 scale printout of the Playfield CAD for reference. Then, carve a small groove from center-to-center to keep the next set of pilot drill holes in line.

Custom Pinball Switch Slot

Spot drill the ends of the slot, then cut grove.

Step 2:

Establish the center line with an X-acto knife, then drill a set of pilot holes in the groove. Use the finish drill size (.198″) as a visual guide to set the spacing.

Custom Pinball Switch Slot

Drill additional holes in the center groove, using the finishing drill bit as a guide.

Step 3:

Once the spot drills are finished, follow-up with the finish drill (.198″) in each pilot hole.

Custom Pinball Switch Slot

Drill to final size using pilot guide holes.

Step 4:

Using the same X-acto, establish the outside walls of the slot with clean cut, using the outer diameter as a guide. Then come back with angled cuts until the slot is clear. Flip over the the other side to complete the slot.

Custom Pinball Switch Slot

Clean up edges with X-acto knife.

 

Playfield :: Design :: Reference

My philosophy is that Pinball is an art form, and a knowledge of current and vintage machines is essential to understanding the “grammar” of this artistic communication. Aesthetic is said to be “Content put into an overall Structure in order to create Meaning”. In the case of Pinball As Art, the content is our flippers, bumpers and targets; the structure is our Playfield geometry and rule set. Speaking the language of pinball means understanding how these elements have been used in the past, and how they work together to create game-play.

Here are four different Playfields that were designed and fabricated within the last three years. I’m posting links to DXFs, SVGs and VP simulations, for use as templates or reference for your own design. Two of these were recently on display at the Seattle Pinball Museum show featuring custom Pinball machines…

Jupiter Crush : 

Click to view the VP simulation, or Right-Click to download the DXF file or SVG file for this table.

This Playfield was designed to be reminiscent of tables from the late 70’s and early 80’s, with features similar to games like Bally’s “Skate Ball”, “Rolling Stones” and “Harlem Globetrotters”. Every game should have a hook or twist that makes it unique, and this game features a Negative Bumper that subtracts points when lit. Reseting the bumper requires a skill-shot to the lower left U-turn.

Jupiter Crush custom pinball machine

Completed Playfield with artwork, mechanisms, lights and plastics, next to the DXF used to fabricate the this table.

 

Retro Spa: 

Click to view the VP simulation, or Right-Click to download the DXF file or SVG file for this table.

Wide-body games were an attempt to make pinball more exciting by adding more features, but unfortunately most of these games didn’t make good use of the extra space. The engineering challenge for this Playfield was to maintain all of the features and game-play of a classic wide-body, while proving it could be done in a standard-size machine. As an added twist, early artwork for the classic game that was rejected 40 years ago was used for reference on the Playfield and Backglass.

Retro Spa custom pinball

Retro Spa completed table with DXF for reference.

 

Tattoo Mystique: 

Click to view the VP simulation, or Right-Click to download the DXF file or SVG file for this table.

This Playfield is meant to be reminiscent of games like “Fathom” and “Blackout”. The simple set of rules is deceptively difficult, with game-theory elements of risk-and-reward designed to thwart those players who are only out to get the high-score.

Custom Pinball Tattoo Mystique

Screenshot of simulation for Tattoo Mystique, and DXF of cutout locations.

 

Miss Adventure:

 Click to view the VP simulation, or Right-Click to download the DXF file or SVG file for this table.

This fourth game in the series is designed to literally “take it up a level”. It has features inspired by classics like “Fan-Tas-Tic”, “Freedom” and “Silverball Mania”, as well as a lower level similar to games like “CFTBL” or “Black Hole”. This lower level is actually intended to be a “virtual” Playfield that will have many different features that can change on-the-fly.

The upper level is also meant to be changeable to keep the game fresh and interesting. The symmetry of the ramps was chosen to allow maximum flexibility of future upper level designs.

Custom Pinball Miss Adventure

White board of Miss Adventure, with DXF.

Playfield :: Fabrication :: Lenses

A majority of the holes you will cut into your custom Playfield will be for Lenses, so this is how we will kick off the actual fabrication of a blank table… Vintage lenses come in several standard sizes, typically 1″, 3/4″ and 5/8″. Rollover targets are also treated as lenses, and are 1 1/8″. Newer games added other sizes and shapes, but we will focus on these, plus a couple of vintage Arrow Lenses. All standard lenses are 1/4″ thick, which is an important feature for fabrication and installation.

Custom Playfield CAD File

Screenshot showing several lens sizes with retaining ledge visible.

Above is a screenshot from a CAD program showing several lens sizes with the retaining ledge visible.

You can find a selection of sizes from many different suppliers, but here are a few examples from Marco Specialties:

Notice that there are a variety of options aside from just color. There are transparent, opaque, star patterns or just plain versions. A couple of  other important things to note:

  • The decision on which lens to use (color vs white, transparent vs opaque, star vs flat) is going to be largely based on what type of lighting you will have, and what the specific application is. I prefer to use LED bulbs under lenses, so I typically go with White or Clear. The vinyl Playfield overlay is translucent, so the final color can be chosen later. If you are using incandescent bulbs, it would be better to use a colored lens. For lenses that have lettering on top (not uncommon), I like plain opaque White. When an indicator really needs to stand out, I go for a transparent colored lens with a star pattern, and same color LED bulb underneath. The end effect looks great and has a vintage feel.
  • All lenses have a letter (e.g. “A”, see above for more examples) molded into the top surface. These have to be removed by sanding. I typically glue the lenses in slightly “proud”, and then sand down the whole Playfield as part of the finishing process. Alternatively, you could pre-sand the them on a belt sander, but the results are sometimes uneven.
Custom Pinball Lens Shapes

CAD drawing of various standard lens shapes, available here.

Here are the steps to drill and insert lenses:

  • Print out your Playfield. This needs to be done full-size on paper using a large-format printer. I do this at Kinko’s or FedEx, and it’s very cheap for black and white.

 

Custom Playfield Fabrication

Apply full-scale CAD layout to blank Playfield.

  • Dimple with spot drill. I typically use a #43 (0.89″) bit, which is the standard pilot size for a #4 screw. Apply your Playfield CAD printout to your blank, and drill through your plywood at the center location of all lenses.
Custom Pinball Fabrication

Spot drill a pilot hole o guide the Forstner bit.

  • Forstner bit front side. Using a “Forstner” bit the same size as your lens, drill down slightly less than 1/4″. I usually make a jig in each lens diameter to gauge depth. When I feel I’m close to the final depth, I’ll slow down the RPMs and stop several times to check with the gauge.
Forstner Bit for Playfield Lens

Drill pocket 1/4″ deep on front side, check with lens jig.

  • Forstner bit back side. After doing all the fronts (usually one size at a time), flip to the back side an use a bit 1/8″ smaller than the lens diameter. This provides a lip or ledge for the lens to sit on. Coming in from the back does two things: you’re using the existing spot drill hole so there’s less drift, and the surface edges will be cleaner since they don’t risk being punched out from the front.
Custom Pinball Playfield Insert

Flip over and drill from the back with 1/8″ smaller Forstner bit.

  • Glue all lenses in. I typically use wood glue in case of mistakes, but you can be more aggressive and use clear epoxy. Use a finger from the back side to level and prevent the lens from dropping to far down. Let the glue dry… then…
  • Sand. I start with about 180 grit to get the plastic lenses flush, then switch to 220 then 320.

There are other processes later that will seal and clear coat the lenses to bring back their shine, and we’ll cover that later…

Playfield :: Hardware :: Bumpers

One of the most ubiquitous pieces of Playfield hardware is the Bumper.

It has at times gone by the name “Thumper”, “Jet” or “Pop Bumper”, but when people say “Bumper” they are generally referring to the switch-and- coil-activated mechanical Bumper that is standard to most modern games. At one time these Bumpers were passive, with just a rubber ring and a switch to add to the score, hence the need to have names to distinguish active Bumpers. But by the time of Pinball’s peak in the mid-80’s, most all Bumpers were active, except for a few notable games like “Silverball Mania” or “Space Invaders”.

Most machines typically have three Bumpers, but almost any combination of number or location you can think of has probably been tried. This is where the grammar and language of Pinball comes in…

If you are unfamiliar with all the Bumper variations that have been used it the past, check out the Internet Pinball Database (IPDB), and the reproductions section of the Visual Pinball (VP) website. When you design your game, you should be aware of what other games have used similar layouts. Even if you are not trying to emulate or reference vintage tables, there will always be some comparison and connotation associated with them. It’s important to understand this grammar so as to not create some unintended meaning.

The “standard” Bumper has undergone some evolution to make things easier for manufacturing, assembly and repair, even though the basic components remain the same. Here are representative examples:

  • Evolution #1 : Added Nutplate: The earliest improvement was to add a plate with pre-tapped holes.

Gottlieb Thumper

  • Evolution #2 : Combined Plate and Switch: The second improvement was a plate with built-in mount for a spoon switch. This unit could be built as a sub-assembly prior to installation.

Stern Thumper

  • Evolution #3 : Molded Plastic : An incremental improvement to number #2, this was probably a cost savings, but also presented a cleaner fit and finish on the top play surface.

Bally Thumper

Any of these would be a good choice for a custom pinball machine. You would want to make the decision early on, however, since the Playfield would have to be drilled to accept the specific hardware. Most likely, you will base this on what’s available in your stock or on eBay.

It’s much cheaper to buy a used Bumper unit, and if necessary rebuild with new top-side parts for cosmetic considerations. A used unit that already has the brackets, coil, metal ring assembly and the switch, can be re-built to like-new condition with the following parts:

Bumper re-build parts

These can be found at Marco Specialties or Pinball Life:

And if you decide to start fresh instead of rebuilding, you can find this as an assembly:

Here’s what the top-side parts look like assembled:

Assembled Bumper Parts

If your assembly already has a base, you probably will not need the Playfield insert. These parts can then be added to the rest of the sub-assembly, making the installation and future repair that much easier.

Downloads:

  • CAD diagram of EV2 version of Bumper, showing Playfield cutout. You can right click here and “save as”, or click through to preview in most browsers. Keep this item as a template in your custom pinball artwork file, then import into Inkscape or other drawing programs.