Let's head out to the workshop bench to do some drilling then to the kitchen sink to remove the paper drilling guides. Do you remember that the glue underneath the guides was washable? 

The drilling is fairly simple since the enclosure is a soft ABS plastic. Drill bits have a tendency to drift away from center of the hole in soft materials like ABS unless you use a drill press. Since we'll be using a hand-held power drill for this build, we'll solve the drifting issue by drilling two successive sizes of pilot holes.

Small pilot holes are the best way to accurately guide larger drill bits. Be patient -- the components will fit better if the holes are drilled with precision. Take it slow and easy. Carefully center the drill bit before spinning the drill. Use light pressure at a slow speed and let the drill bit do the work.

  • Start by drilling 1/16 inch pilot holes in the center of each hole marked on the drilling guide. The holes to be drilled are yellow circles with a small black dot in the center.
  • After drilling all the hole centers with the 1/16 inch drill bit, repeat the process and enlarge all the holes with the 1/8 inch drill bit.

Because the final diameter of many of the 27 holes is 1/8 inch, only eight larger holes remain to be drilled at this point. Let's start with the two largest holes, 1-7/8 inch. These are for the carbon filter in front panel and the fan in the rear panel.

Clamp the enclosure to your work surface to stabilize it when using the larger drill bits and hole saw. Two clamps placed as shown should do the job.

A sharp hole saw will do most of the work for you. Your primary job is to apply a light, even pressure and to keep the hole saw level while drilling. 

Hole saws can create a lot of torque that can cause the power drill to suddenly stall and jerk, damaging the enclosure. In addition to spinning the drill at a lower speed and letting the hole saw do the work, set the power drill clutch to a medium setting. If the hole saw grabs or stutters, the clutch will keep the power drill from suddenly twisting in your hands.
  • Using the 1-7/8 inch hole saw, start drilling by placing the hole saw's pilot bit point into the previously drilled pilot hole. Run the drill motor at a low speed.
  • After the saw completes the hole, pry out the plastic circle that's inside the hole saw, flip the enclosure, secure the clamps, and drill the second 1-7/8 inch hole.

 

The final eight holes will require a special drill bit that can cut a variety of hole sizes. The step drill bit shown below can create hole sizes from 3/16 to 7/8 inch, perfect for our remaining 1/4, 3/8, 9/16, and 7/8 inch holes.

A step drill bit works very well with plastics, smoothly cutting a precisely round hole. The trick is knowing when to stop drilling -- when the step drill bit has reached the correct diameter. You will be able to feel it as the drill moves from one diameter to the next. If you haven't used a step drill bit before, try it out on some scrap material and get the hang of it before drilling the enclosure.

Operate the step drill bit at a slow speed using light pressure. Hold the power drill level while drilling. The step drill bit should create some nice spirals of cut plastic if you're doing it correctly.

 

  • Using the step drill bit, drill each of the remaining eight holes to the size printed on the drilling guide.
  • Use a hand countersink tool to remove any burrs from the smaller holes. A small file can be used on the larger holes to smooth away any roughness left after drilling.

 

 

At this point in the process, you will only be able to remove burrs from the enclosure's exterior. Keep the countersink and small file handy for later. You'll have the opportunity to clean up the interior after the guides and front panel are removed.

After creating a nice mess in the workshop, it's time to head to the kitchen sink and remove the drilling guides.

  • Peel off all the blue tape and as much of the paper as possible. Rub off the remaining paper and glue under lukewarm running water. The washable glue will completely dissolve. Dry with a paper towel.
  • Remove the front panel screws and eliminate any interior burrs with the countersink and a small file.

 

Here's a glamour shot of the enclosure after drilling. We'll need room to fiddle with the wiring, so the acrylic rods and the prismatic plastic window will be attached later.

Now on to the electronics part of the project!

This guide was first published on Aug 15, 2017. It was last updated on Aug 15, 2017.

This page (Drill the Holes and Remove the Guides) was last updated on Aug 01, 2020.