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

 

 

 

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.