Control :: Electronics :: Solenoids

This is a follow-up to the original post on controlling solenoids with a Pinball Controller’s “Power Driver 16” board. I’m adding some photos to aid with the wiring and assembly, as well as giving a few troubleshooting tips.

Overview showing the Power Driver 16 and the Mini RS-485 Master

Click through to see a larger image. This is an overview of the Power Driver 16 and Mini RS-485 Master, showing the inputs, Mini Master output, and connection to the solenoid driver.

Detail of the Mini Master connections.

Click through to see a larger image. This detail shot shows the inputs to the Mini Master: Orange wire is Power (5V), Blue wire is TX from the Arduino, Black is GND. The outputs of the Mini Master are: White for TX(+) and Black for TX(-).

Detail of the RS-485 lines running to the solenoid driver.

This is a detail showing the Mini Master output coming in on the Pinball Controller’s Power Driver 16 port labeled J9. Pin one is Serial +, which gets the White TX(+) wire, and pin 2 is Serial-, which gets the Black TX(-) wire from the Mini Master.

Arduino connection of the SPI interface to the Mini Master RS-485 converter.

Click through for full size image. This shows the Arduino SPI interface to the Mini Master RS-485 converter. It is a three-wire connection, with 5V power, signal and ground.

Arduino pinout showing SPI interface pins.

 

SPI interface uses the GND, MOSI and 5V pins when connecting to the Mini Master RS-485 converter.

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Cabinet :: Fabrication :: Miter

If you decide to go the route of building a Custom Pinball Cabinet from scratch, one of the biggest fabrication challenges you will face is how to get clean looking corners…

Most of the cabinet edges will either be covered with some form of trim, or not visible except from the bottom or from the back. The features that can’t escape attention, however, are the two vertical edges of the front panel on either side of the coin door. For a professional-looking quality Cabinet, these two corners will need some form of mitered edge, and the feature of choice for Pinball Cabinets has been to use a “Miter-Lock”.

The front vertical edges of the Cabinet are the most visible, and need a mitered edge in order for the Cabinet to have a clean professional look.

A Miter-Lock edge is created on a router table with a single Miter-Lock Bit, with the two panels of wood being passed through the cutter either laying flat or standing vertical. Below are a set of images showing a typical Miter-Lock Bit installed in a bench-top router table:

Typical “Miter-Lock Bit” installed in a bench-top router table.

The bit itself is like a typical 45 deg cutter, but with two distinct jogs in the middle. These jogs create self-interlocking edges when two pieces of plywood are cut horizontally and vertically.

The panels that need the Miter-Lock are the two sides (front-edge only), and the front panel (both side edges). Since the side panels are very large and unwieldily, it makes more sense to run these flat through the router, and run the smaller front panel vertically. See the pics below:

Run the small, easer to handle, front panel through the cutter vertically.

Running the front panel through the cutter vertically (above), and the side panel through flat (below), creates a mirror cut that is self-locking.

Larger cabinet side panel being run through the router flat, cutting the front vertical edge.

When done correctly, the Miter-Lock Bit will cut two mirror-image edges, creating a self-interlocking corner. This process should only be done by those who are experienced with the equipment and use of a router table. Aside from the typical set-up, the important adjustments for this cut are to get both the height and offset equal and matched to the thickness of your wood panel (in this case, 3/4″ 7-layer plywood).

Any mis-adjustment in height or offset will cause one edge to stick out farther than the other. Not a disaster, but does’t look as nice and could cause the overall dimensions of the cabinet to be skewed.

Below are a couple images showing how each of the finished edges should look, and how they fit together:

 

Example of how each Miter-Lock cut looks, and how the two edges fit together to create a self-locking joint.

One final tip I have is how to avoid having the vertical edge chip out during the routing process. Now, in a perfect world, we would have the grain of the wood running vertical along the cut line. But, because our side panels are just longer than 48″, it’s not possible to lay out the whole cabinet in one sheet when the typical grain runs length-wise. (Stay tuned for updates, I’m working on a slightly more compact cabinet that will rotate the layout to match the grain).

Below are a panel of images depicting a method that avoids the thin top laminate from chipping out during the vertical cut:

To avoid having the top laminate chip-out, you can pre-score the cut line with an xacto knife.

Here are the steps to avoid chip-out (the first panel is an example of the disastrous results of cutting across the grain…):

1. Using a same-thickness piece of plywood as a guide, line up a straight-edge ruler 3/4″ away from the outside edge. Bear in mind that the face of the panel we are cutting is the inside, the “beauty” side should be face-down.
2. Clamp straight-edge to the panel, preferably at both ends, and preferably to the table as well.
3. Using an Xacto knife, cut along the edge through the to laminate layer. This will be about 1/16″ depending on what grade your using.

Tip: The metal straight-edge is to the inside of the cut line. This means if you make a slight mistake with the Xacto, you’re only messing up a surface that will later be removed. It’s best to use a new, sharp blade, but with a new blade you always need to make your first cut with a VERY light hand, and then come back with several passes to get the cut deeper. It is very easy to get of track with a new blade.

Good Luck and Be Safe!

 

 

 

Cabinet :: Fabrication :: Stencils

There are several ways to create the look of a vintage stencil for your cabinet artwork. I’ve done it a couple of different ways, and you can make your choice based on complexity and resources available.

I typically go for a three-color design (base coat plus two stencils), in keeping with the classic style, which can also be an artistic challenge.

1) Original method. Vintage machines had their paint applied by spraying, stippling or flicking with a brush, usually masked with some type of stencil. This would have been a rigid, thick cardboard paper (or thin wood), with patterns cut into them, and intended for multiple use, possibly hundreds of times.

Advantages: Multiple use (as in production), and has a classic look.
Disadvantages: Investment to make, not as sharp or modern looking.

2) Hand Mask Method. This is as simple as it sounds: use masking tape and paper to create your stencil directly on the cabinet wood. For smaller details, I usually print out a template I’ve designed on the computer. The larger elements I would freehand with some scale drawing for reference. This works best if using mostly straight lines or slight curves. Something more complicated would need a more elaborate method.

Advantage: Cheap.
Disadvantages: One-time use (possibly not repeatable), not as precise.

Creating a stencil by hand, using masking tape and a printed template. Base is white, first color dark blue, third color orange.

3) Pre-cut Stencil. This is usually a one-time use vinyl stencil, and will cost about $150. This is a method to use if you have a very specific pattern in mind, and usually requires a vector artwork drawn on a computer. You might be able to find a local company that can do vinyl cutting, or use a company like Twisted Pins that makes one-time stencils specifically for pinball machines.

Advantages: Very precise complex shapes, exactly rendered.
Disadvantages: Cost, and probably will only get one use.

Using a one-time vinyl stencil to achieve complex shapes and curves. Again, base is white, first pass is dark purple, then pink.

 

For reference, if you are following the plans for this cabinet and head unit, here are the PNG files for the Side, Front and Head that can be used as a pattern for creating your own artwork:

Side art work for reference or use as a pattern.

Three-color head unit artwork for use as a pattern or reference.

Stencil for front of cabinet. If you have the vinyl cut professionally, the shop should be able to take your PNG file and convert it into vector artwork, then generate two separate stencils for a three-color design (two plus base).

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 :: 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…