Playfield :: Hardware :: Flippers

If you are contemplating building your own machine, then you probably already know a good bit about how pinball machines work. It’s basically series of electro-mechanical events where a steel ball activates a switch, which in turn fires a solenoid that drives a mechanism, sending the ball off in some other direction where it most likely hits another switch, and so on and so on…

The Flippers are the only real interface to the game: You manually activate a switch that fires a solenoid, which then drives the flipper mechanism… The issue that becomes apparent with Flippers is that you want high-power (and high current) when you’re hitting the ball, but you don’t want to burn out your flipper coils if you hold the buttons too long. These problems have been solved during the long evolution of Pinball, with somewhat complicated results.

It’s understandable that there are often questions about connecting and firing Flippers; With their double-wound coils, multiple recirculation diodes, and end-of-stroke (EOS) switches, it’s easy to get confused if you’re hooking them up for the first time. And to make things more complex, today’s modern control systems have the ability to do many more things, like fire the “power” and “hold” coils independently, apply “patter” to the coils, feed the EOS switch into the controller as a normal switch, or even bypassed it completely.

I’m not going to make a case for what is the best way, but I will elaborate on each of the pro’s and con’s and let you decide what works best for your own Custom Pinball Machine…

Background on the standard 70’s- or 80’s-style setup:

Most early games fired the Flippers directly off of the cabinet flipper buttons, using high-power contact switches. In addition to this, there was some sort of relay in series with the circuit that could enable and disable the flippers between games, or even between balls. Here’s a diagram of a standard vintage-style setup:

Typical vintage circuit for enabling pinball flipper mechs.

And typical vintage-style EOS switch setup and function:

Typical End-of-Stroke switch setup and function.

In the above diagram, the EOS switch is Normally Closed (NC) before activation. The switch is shorting out the “Hold” coil, which is a higher resistance and would otherwise limit the current. One the Flipper has reached full stroke, the EOS switch opens, adding the “Hold” coil to the circuit. This reduces the current while maintaining enough of an electro-magnetic field to keep the solenoid in position. On a side note, the typical convention for labeling coils is to indicate the wire gauge, followed by the number of turns. So “25-500” is 500 turns of 25Ga magnet wire. The hold coil is labeled “34-4500”, so 4500 turns of 34Ga magnet wire. Low gauge is thicker wire, with less resistance and higher current carrying ability. Resistance also increases with length. So more turns at a higher gauge will yield a much higher resistance than fewer turns at a lower gauge, even if the same amount of copper is used.

Speaking from personal experience, about half of my Custom Pinball games use this type of setup. The specific relay (and corresponding socket) that I have used to enable the flippers can be found here:

• K10 Relay : PB325-ND
• Socket: PB642-ND

 

Standard K10 form-factor relay, DPDT suitable for pinball.

Typical K10 relay socket with terminal connections.

You have a couple of options in wiring up this circuit. I like to have the relay on the high-voltage side of the flipper coils, and use the cabinet buttons to switch the ground side of the coil.

If you’re interested in using this old-school method, or possible have scavenged parts from vintage machines, here are a couple links that describe how these older circuits work, and how to properly repair older Flippers:

• http://stevekulpa.net/pinball/bally_flipper1.htm
• http://techniek.flipperwinkel.nl/wpc/index3.htm

Old-school Advantages:

Zero latency from button push to firing the flippers. And, only one solenoid driver channel is used, just for the relay.

Old-school Disadvantages:

As simple as the circuit is, it can be a lot of wiring to get power, ground, buttons, flippers, and solenoid driver lines all to a central relay. Power of the flippers are not independently adjustable.

Variations on the Old-school circuit:

From a power supply standpoint, one concern with flippers is that their high-power coils produce large current surges (see the previous blog post for more info on power supplies). This could become a problem particularly on multiple-flipper games. However, I have wired four-flipper games in parallel without any issues. If it is a concern when building your own Custom Pinball Machine,  there are clever variants that uses the EOS switches to stagger the firing of the upper and lower flippers. The advantage being that the surge current is spread out over time, so each flipper gets the full power available. Primary flipper requires a DPST leaf-switch, circuit diagram here:

Staggered firing of multiple flipper coils using the primary EOS switch, reduces surge current.

Modern Systems:

If you’re building a Custom Pinball Machine, the controllers and drivers available today allow for independent firing of both the “power” and  “hold” coils, or they can adjust the duty cycle of the voltage to the solenoid so that only a single “power” coil is needed. The EOS switch can be used to tell the controller to go to a much lower duty-cycle, or the EOS switch can be bypassed completely and a timer function used instead to switch to a low-power mode. This modern technique uses PWM, sometimes called “patter”. Here is a good breakdown of the various methods that can be used today:

• Mission Pinball Flipper Reference

Modern Advantages:

It’s much easier to wire flippers directly to the driver, and have cabinet buttons go to the controller. I currently have two Custom Pinball Machines wired this way, and I can see how the ease of wiring justifies the downsides. Plus, you have full control over flipper power, and could even manipulate the power as part of the game rules.

Modern Disadvantages:

Having the Flipper buttons sent to the controller, and then the controller signal sent to the driver, can introduce latency (that is, a significant delay between pushing the button and seeing something happen). This is by far the most commonly cited disadvantage. However, I can say from personal experience that it’s barely noticeable (or not detectable at all), even with a relatively low-speed controller like an Arduino. With that said, there are other potentially more critical disadvantages… Eliminating the EOS circuit is not “Fail Safe”. Having the high-power coil under computer control could lead to problems, especially during development and testing, or as a machine gets older and less reliable.

Another disadvantage is that configurations firing two coils per Flipper (independant “power” and “hold”) can eat up available driver channels pretty quickly, especially on multi-flipper games. But this would only be a corner case where the EOS switch was eliminated, while retaining the “hold” coil (as in situations where PWM “patter” drive is not an option).

Where to Buy:

Aside from eBay, and especially if you want new hardware, the best places to buy Pinball Flipper Mechs are from Marco Specialty or Pinball Life:

• Marco Specialty: Stern Flipper Assembly 500-6543-04
• Pinball Life: Bally Flipper Assembly pbl_C-13174-R_C-13174-L

Reproduction Bally Flipper Mech available from Pinball Life.

Reproduction Stern Flipper Mech from Marco Specialties

 

 

 

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Playfield :: Electronics :: Switches

Switches are probably the single-most important device on a Pinball Playfield, and are fundamental to the game itself. The entire Pinball Machine is essentially an electro-mechanical interaction, with the switch being the all-important middle-man between the ball and the active mechanisms…

Switches also pre-date a lot of the other devices we commonly associate with Pinball, like Flippers, Thumpers, Slingshots, etc. and most machines today still use some manner of the traditional wire-form activated leaf-switch we find on older games.

The focus of this blog is on solid-state based Custom Pinball Machines, and one advantage with SS when it comes to switches is that they can be scanned as a matrix. Most SS games since the 70’s have used this technique. With matrix scanning, you can read 40 switches with 5 drive lines and 8 read lines (5×8 = 40), but only use 13 digital I/Os (5+8 = 13). And just to hammer home the math, that saves 27 I/Os (40-13 = 27), putting this in the wheelhouse of a small micro-controller board like the Arduino Uno.

The Layout.

Here’s a typical schematic (below) of a switch matrix from a standard Bally 70’s solid-state (SS) game. I present this because it will serve us well even today since the principles are the same.

Schematic of a switch matrix designed to be scanned by solid-state electronics. For our Custom Pinball Machine, we will use a micro-controller like the Arduino Uno.

 

Scanning The Matrix:

In the case above, there are five drive lines and eight sense lines, which we will model for our own design. The process of scanning works like this:

• All the drive lines are initially held low.
• The first drive line is switched high.
• Each of the eight sense lines are read.
• These values then represent the state of switches 1 thru 8.
• The first line returns low, and the second line goes high.
• Again, read in the eight sense lines.
• These values become the state of switches 9 thru 16.
• And so on until all 40 switch states are read…

Notice that each switch in the schematic has a diode on the drive side. This prevents “ghosting” in the case of multiple switches being active at the same time. Without it, the current from one drive column could back-feed through any switches active on the same row, in essence driving a second (unintended) column. An active switch on the second column would create a “ghost” activation on the first (real) drive column.

Below is a spreadsheet I usually create during the design of the game, and reference for the assembly and wiring.

Excel spreadsheet showing switch signal names with drive wire colors and sense line colors.

Most older games made use of two-color striped wire, so there was never a duplicate color combination for any signal. In our case, it’s more feasible to use a limited set of standard colors, and just keep track of where there might be duplicates.

I always create a chart like this early on, giving the switches logical names and grouping them based roughly on where they will be located on the playfield. It helps to use the same name later in the Arduino code that will be doing the scanning.

The Switch.

Almost all older games use leaf-switches connected to a wire-form for activation. These usually have three contacts, and the diode mentioned above is mounted directly on the switch. This make wiring easier and more mechanically stable.

 

This is a typical “spoon” switch used to activate Thumpers. There is a built-in diode, with the drive wire coming in on the positive side (yellow), and a sense wire on the negative side (orange).

The Code.

Below can be cut-and-pasted into an Arduino project. Use this for testing and diagnostics, or as a reference for creating your own game code.

There are several features to this code aside from just scanning the switch matrix, hopefully it will become clear as you read though it:

• The code compares the previous state of the switch to the current state to determine if the state is “new”
• It then rotates the state for the next loop so that current becomes previous.
• It only call the state “new” if it went low-to-high, you can change this in your own code.
• It implements a de-bounce timer function, which is adjustable, or just comment it out.
• Prints the “new” switch state to the serial monitor when switch is activated.

// --------------------------------------------
/*  
INSTRUCTIONS:

This code will scan a 5x8 switch matrix and print the status of new switch states.

CODE FLOW:

  -  Set the first drive line output.
  -  Scan first input.
  -  If state was low, and now high, set new switch flag.
  -  Send message out to Serial Monitor (optional).
  -  Loop through all eight inputs.
  -  Loop through all five drive lines.
  -  Delay.
  -  Repeat.
  
For questions or comments, check the blog:
https://howtobuildapinballmachine.wordpress.com

*/

//  --------------------------
//  BUILD VARIABLES HERE
#define DEBOUNCE_MODE 1
#define SERIAL_MONITOR 1

//  --------------------------
//  VARIABLES
unsigned char j = 0;	//
unsigned char i = 0;	//
unsigned char k = 0;	//

//  --------------------------
//  SWITCHES
unsigned char switchStateNow[40];	// start no digit selected
unsigned char switchStatePrev[40];	// start no digit selected
unsigned char switchNew[40];	//
unsigned char switchDebounce[40];

// --------------------------
// DEFINE SWITCH NAMES HERE
// optional for this test code, but good idea
// if you are going to build on this as a game later.
enum
{
SWITCH_0,
SWITCH_A, // was 1
SWITCH_B, // was 2
SWITCH_C, // was 3
SWITCH_D, // was 4
SWITCH_5,
SWITCH_6,
SWITCH_7,

SWITCH_8,
SWITCH_9,
SWITCH_10,
SWITCH_11,
SWITCH_START,
SWITCH_COIN,
SWITCH_KICKER,
SWITCH_ROLLOVER,

SWITCH_LF_SPINNER, // 16
SWITCH_LANE_DROP_1,
SWITCH_LANE_DROP_2,
SWITCH_LANE_DROP_3, // kicker / shoot again
SWITCH_LANE_TARGET,
SWITCH_MID_TARGET,
SWITCH_22,
SWITCH_RT_SPINNER,

SWITCH_THUMPER_1, // BLACK - ORANGE
SWITCH_THUMPER_2, // BLACK - GREEN
SWITCH_THUMPER_3, // BLACK - BLUE

SWITCH_LANE_R_1,
SWITCH_LANE_E,
SWITCH_LANE_T,
SWITCH_LANE_R_2,
SWITCH_LANE_O,

SWITCH_SHOOT_LANE,
SWITCH_LF_OUT_LANE,
SWITCH_LF_RET_LANE,
SWITCH_LF_SLING,
SWITCH_OUTHOLE,
SWITCH_RT_OUT_LANE,
SWITCH_LOW_1_THUMP, //SHOOT_LANE,
SWITCH_LOW_2_THUMP // 39
};

#define SWITCH_DEBOUNCE_DURATION 10 //10 loops

void setup() 
{  
  pinMode(14,OUTPUT); // analog in used a row drive out
  pinMode(15,OUTPUT);
  pinMode(16,OUTPUT);
  pinMode(17,OUTPUT);
  //pinMode(18,OUTPUT); // if only using four drive lines, no need to set this

  pinMode(2,INPUT); // analog in used a row drive out
  pinMode(3,INPUT); // analog in used a row drive out
  pinMode(4,INPUT); // analog in used a row drive out
  pinMode(5,INPUT); // analog in used a row drive out
  pinMode(6,INPUT); // analog in used a row drive out
  pinMode(7,INPUT); // analog in used a row drive out
  pinMode(8,INPUT); // analog in used a row drive out
  pinMode(9,INPUT); // analog in used a row drive out

  digitalWrite(2,LOW); // pull up on
  digitalWrite(3,LOW); // pull up on
  digitalWrite(4,LOW); // pull up on
  digitalWrite(5,LOW); // pull up on
  digitalWrite(6,LOW); // pull up on
  digitalWrite(7,LOW); // pull up on
  digitalWrite(8,LOW); // pull up on
  digitalWrite(9,LOW); // pull up on

#if (SERIAL_MONITOR == 1)
  Serial.begin(9600);           // start serial for output
#endif

//  --------------------------
//  INITIALIZE SWITCH STATE ON, SINCE WE TRIGGER ON RISING EDGE
  for (j = 0; j < 40; j++) 
  {
    switchStateNow[j] = 1; //
    switchStatePrev[j] = 1;//
    switchNew[j] = 0;
    switchDebounce[j] = 100;
  }
  
} // end setup

void loop() 
{
  //  *****************************************
  //  -----------------------------------------
  //             START READ SWITCH
  //  -----------------------------------------
  //  *****************************************  

  // SET DRIVE LINES HERE
  for (j = 1; j < 5; j++) 
  {
    // START ALL LOW (no signal)
    digitalWrite(14, LOW); // pins 14-17
    digitalWrite(15, LOW); // pins 14-17
    digitalWrite(16, LOW); // pins 14-17
    digitalWrite(17, LOW); // pins 14-17    

    // DRIVE ONE LINE HIGH
    digitalWrite((j+13), HIGH); // pins 14-17

    // WAIT HERE FOR RISE TIME
    delayMicroseconds(400) ;
    
    // START SCAN
    for (i = 0; i < 8; i++) 
    { 
      switchStatePrev[((j*8) + i)] = switchStateNow[((j*8) + i)]; // rotate variable
      switchStateNow[((j*8) + i)] = digitalRead(i + 2); // pins 2-9

      // check for a "new" state
    #if (DEBOUNCE_MODE)
      if ((switchStateNow[((j*8) + i)] == switchStatePrev[((j*8) + i)]) || (switchDebounce[((j*8) + i)] > 0))
    #else
      if ( switchStateNow[((j*8) + i)] == switchStatePrev[((j*8) + i)]) 
    #endif
      {
        switchNew[((j*8) + i)] = 0; // same as old
      } // end if
      
      else // must be new if not old and new equals one
      {
        if (switchStateNow[((j*8) + i)] == 1)
        {
          switchNew[((j*8) + i)] = 1; // new
          
          #if (DEBOUNCE_MODE)
            switchDebounce[((j*8) + i)] = SWITCH_DEBOUNCE_DURATION; // set timer
          #endif
          
          #if (SERIAL_MONITOR == 1)
            Serial.print("Switch = ");
            Serial.print((j*8) + i); // TODO check this formatting later
            Serial.print("\r\n");
          #endif
        }
      } // end else
    } // end for i
  } // end for j    

  #if (DEBOUNCE_MODE)
    for (j = 0; j < 40; j++) 
    {
      if (switchDebounce[j] > 0) 
      {
        switchDebounce[j] -= 1; // ramp down to zero
      }
    }
  #endif

  delay(10) ; // 10ms loop time
  
  // end read switches

//return;

} // end MAIN LOOP

 

 

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.

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.

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.

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.

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.

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 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.

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.

White board of Miss Adventure, with DXF.

Playfield :: Fabrication :: Blank

The standard Playfield is fabricated from 1/2″ plywood, and is 42″ x 20.25″.

There are many types and sources for plywood, but unfortunately the actual type specifically used for vintage Pinball Playfields is no longer available (see this useful  FAQ from CPR), so the best solution is to try and find something better than the original. You will probably see a lot of options for cores and laminates, and it can be confusing. A lot of the information is good, but not very useful if you’re on a budget or don’t have access to lumber yards or big suppliers nearby.

I’ve tried several options, and luckily one of the best ones is cabinet grade plywood from the local hardware store. But here’s the key: it needs to have lots of plys for stability. This is what will keep your Playfield flat, straight and warp-free in the years to come. Look for at least a 9-ply count, bearing in mind that the surface veneers count as plys but are slightly thinner. Birch is not hard to find, works well and looks great. Another advantage is that your local hardware store is likely to have this in a 2’x4′ sheet size, so you are not wasting wood or money.

Birch veneer, 1/2″ thick nine-ply cabinet-grade plywood from the local hardware store.

Most vintage tables used Maple top with a hard core (and no voids). If you have the resources, this is still an option, but I personally think the additional cost isn’t worth it. For short-run production… maybe, but we’re talking Pinball as Art here, and designing something for production would take away from that.

To get started, here’s a Playfield blank based on vintage 70’s-80’s Bally hardware. It is similar (or the same) as Stern and Williams from that era, and parts are easy to find:

Bally blank Playfield template.

You can find a link here to a DXF and SVG version, for use in a CAD or Illustration program respectively.

I usually will purchase a sheet of 2’x4′ plywood and use a T-square to measure out 42″ x 20.25″. Take a look at the surface of both sides first, and decide which will give the best finish on top. I use a bandsaw, but a circular or table saw will work for these initial cuts.

Second step is to cut out the lower edge notches, which are clearance for the shooter (right) and cabinet flipper buttons. Again, here I would print out your CAD layout 1:1 scale and tape to the surface as a guide. You will want to use a band saw or jig saw for this, and to make it look really clean I use a 1/2″ Forstner bit in the corners first to establish the right radius.

The rest of the Outhole Kicker cutouts can be done the same time you’re doing the lenses and other hardware openings.

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.

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:

• Playfield insert 1″ round green star #PI-1FGS
• Playfield insert 3/4″ round Orange #PI-34RO
• Playfield insert 5/8″ round White opaque #PI-58RW
• Playfield insert 1-1/2″ triangle Green #PI-112TGT
• Rollover star button housing red 3A-7537 #C-901

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.

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.

 

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.

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.

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.

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.

• 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.

• 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.

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:

These can be found at Marco Specialties or Pinball Life:

• Pop bumper cap red star – Stern #13A-12-1
• Pop bumper base 03-6009-A5 #C-115-1
• Pop bumper body 03-9675 #C-114-3
• Ring and rod assembly 60-1705 #A-4754
• Pop bumper skirt – white #03-6035-5
• Lamp socket small bayonet pop bumper #E-120-25
• Spring – compression pop bumper 10A-7 #10-7

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

• Pop bumper lower bracket assembly #515-6459-04

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

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.

Playfield :: Hardware :: Apron

To kickoff the Playfield section of the custom pinball blog, I’ll start with something relatively easy: the Playfield Apron.

This will be very important later, as the dimensions of the chosen Apron will have an impact on the table layout. Most Aprons are standard width, but there will always be slight variations that will have to be accounted for or modified. Since Playfield geometry is defined from the bottom-up, it’s critical to get the Apron mechanicals established before laying down the rest of the hardware.

As with most posts, I’ll will try to outline two or three fabrication methods to chose from… And will post links later to CAD or graphics files for download.

Step 1:

Decide New Or Used. The Apron is one of those pieces of standardized hardware (like Thumpers, Drop Targets and Flippers) that you will want to source from either a parted-out machine or buy new. Since we are customizing here, it makes sense to find a used one that would otherwise be thrown out. For this purpose, we check eBay (try searching simple keywords like “pinball apron”). You should be able to find a rusted-but-decent one for around $15, minus shipping. To be consistent with this blog, get a “standard” size one, not a “wide body”.

Step 2:

Sand, Clean and Paint. I use an orbital sander, which I recommend, since you will want to sand all the way down to the bare metal. I start with a medium grit disk, around 180, to take off paint as quickly as possible, then 220 and 320. For this first pass at 180 grit, you don’t want to use too much pressure, since any gouges will have to be sanded out later or will show up in the finished product. Once most of the paint is off, wipe clean with a rag and follow up with 220, and then again with 320. Wipe down and clean with isopropyl, then use Rust-oleum or some similar spray enamel in the color of your choice. If you’re going for a light color, best to use a white primer, and sand lightly with 320 (by hand) between coats.

This orbital sander has been a good choice.

Step 3:

Add Artwork. Here’s where we come to some alternate fabrication choices based on what look you’re after and what tools you have at your disposal…

• My first example is probably the easiest and yields decent results. If you have a computer and printer, you can create your artwork in a vector graphics program (like Inkscape, which is free) and print out onto gloss sticker sheet paper. The Apron in the photos below was done this way. Before applying to the painted surface, I spray the paper stickers with a matte acrylic designed for sealing artwork, sometimes called a fixative. This gives the paper a longer lasting finish.

Rusted vintage Apron that was being thrown out.

Same Apron, after first coat of paint.

Finished Apron with graphics applied.

• Second example is a little more complicated, but gives professional-looking results if you have access to the equipment. Using a vinyl cutter (like a Cameo Silhouette), your same vector artwork colors can be cut individually and stacked to give the impression of a silk-screen process. The results are cleaner and will probably last longer. The example in the photo below was done with the vinyl cutting method.

Old apron sanded and cleaned.

Painted with high gloss enamel.

Finished apron with vinyl decals applied.