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…

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s