Quarks Kit Arrived — Drilling in MDF

Due to weather (or so is the official story) My Quarks kit finally arrived, after spending two weeks on icy roads in FedEx Trucks going across the country.

Flat-Pack Kits

DIY Soundgroup was great to deal with and the kit arrived well packaged:

The kit includes two “flat packs”, which means CNC routed MDF pieces with rabbets in them and a front baffle with rounded edges and cutouts for the drivers already made. All the other pieces are included as well: Drivers, parts for the crossover (passive circuitry implementing highpass/lowpass filters for the woofer and the tweeter), the port tube, screws, speaker gasket, etc…

The only thing you need to do besides gluing pieces together for the flat-pack is to drill holes for the binding posts (the pieces you connect your speaker wires to).

Here is an over-engineered way of doing this:

Holes For Binding Posts

Since there is still a moratorium on power tools in our garage, I decided I can at least sneak out into the garage and glue the flat packs together. — The only thing left to do before this is to drill two holes in the back for the binding posts, which is where you will eventually connect the speaker wire once the project is done. Since hole drilling can be done with a relatively quiet hand-held corded drill we can circumvent the power tool moratorium here…

The binding posts require you to drill two 7/32″ holes. — Great, who comes up with these oddball fractional numbers? — For precise drilling in wood I own a set of brad point drill bits. These are drill bits with a sharp tip in the center, that makes it easy to very precisely position the drill. They also have flared edges to supposedly give you a better cut. (If you still can’t picture what a brad point drill bit is, here is an example for one…)

Problem: I don’t have a 7/32″ brad point drill bit. However, I own another set very similar to this set of drill bits that does include a 7/32″ bit.

What i ended up doing

  • Take the 1/8″ brad point tip bit and start by drilling 1/8″ holes. This allows for very precise positioning. Of course, there was a little bit of tear-out when the bit went through on the other side.
  • Next, take the 7/32″ bit, the tip of which is now easily centered in the 1/8″ hole I just drilled. Then drilled half-way through, turned the piece of MDF over and drilled through from the other side. This prevented tear-out on the 7/32″ holes and took care of the small amount of tear-out caused by the 1/8″ bit, because all that material was removed.
  • Finally, stick the 7/32″drill bit through the hole and give it a few quick spins, to remove any burrs that might be in the center, where you broke through.
  • After drilling the holes there was a little bit of a welt left around the holes on each side. — A few strokes with sandpaper quickly to care of that.
  • Tip: When drilling through MDF: Lower RPM but a little more pressure than when drilling through wood seems to work best.

Did I over-think this? — Probably…


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