Last year, I spent a few weeks of the summer in Cambridge. Amongst other things, it was a great opportunity to hang out in Makespace with my good friend Michael and continue working on my Anytime x Nixie project–the Nixie tube-based world clock I’m building.

Since Michael currently spends his time creating electric guitars, he’s a great person to turn to to create a beautiful case for the clock, and we had a lot of fun doing just that: in under two weeks, we produced a number of PLA prototypes, CNC’d main box, laser-cut a base, and printed some custom feet. You can find Michael’s notes on the process here, and here.

Coming together

In previous posts, I described the process of designing and building the electronics for the clock, and creating the firmware to control the Nixie tubes. In this post, I’ll focus on designing and assembling the case:

  1. Design and prototyping
  2. Testing the design on the CNC router
  3. Machining the wood box
  4. Laser-cutting a base
  5. Printing the feet
  6. Finishing up
  7. Next steps

Design and prototyping

Michael kicked things off by using Fusion 360 to produce some designs for the case–you can export PCBs directly from EagleCAD into Fusion 360, so we were able to try everything in place without creating a single part. Once we had something we were happy with, we set about printing, testing, and revising the design.

Fusion 360 screenshot showing some components assembled

Some early design ideas

We made use of Makespace’s Ultimaker 3 extrusion printers for our prototypes, printing in PLA. These are quick and [fairly] reliable; ideal for rapid iterations. We did encounter a number of printer failures during the process–a snag in the PLA spool killed our first print, and the unusually hot British summer caused a number of prints to deform a little–but after a few days, we’d seen enough to have confidence in the design.

Clock with a half-printed case

Making the most of a failed print to test some dimensions

We ultimately went through a number of variants of the case, tweaking clearances, adding a cut-out for the USB port that will power the clock, and adding air vents to ensure things don’t overheat.

Vents

Rear of the clock, complete with USB port and vents

Testing the design on the CNC router

Having decided we were happy with the overall design, we next set about figuring out how to cut it out of wood using the CNC router. This is more complex than the extrusion printer, requiring multiple phases, with tool changes in between, and turning the material in the process.

To convince ourselves we had everything planned correctly–and to avoid wasting our beautiful olive wood–we glued a few layers of MDF together and tested with this.

The completed part waiting to be cut away from the block of wood

Happily we got most things right the first time around, and using the MDF allowed us understand just how careful we needed to be when drilling out the rear vents.

Machining the wood box

For the final case, I picked up two blocks of wood–Wenge and Wild Olivewood–from Exotic Hardwoods UK Ltd, ultimately selecting the olivewood. We found ourselves with a block of wood significantly larger than necessary, so I should be able to get a number of clock cases (or other projects) out of it.

We repeated the CNC steps we’d practised on the MDF and, fortunately, everything went according to plan, leaving us with a beautiful box.

Olivewood Complete

If you look closely in the above image, you can still see the tabs that the router leaves in place to connect it to the main block so it doesn’t move around during cutting. These need removing manually as part of the finishing process. The router is also unable to drill the rear vent holes as they’re perpendicular to the body of the case, so we did that manually, placing a support block inside the case, and using a pillar drill:

Ready to drill

Cutting the wood is really only the first part–after that, it’s a matter of sanding and then finishing. Sanding involves working through gradually higher and higher grit sandpaper until the wood has almost a silken plastic-like quality. It’s amazing how different it both looks and feels after this process.

Sanding the case to a perfect finish

Sanding is a time consuming process, and we spaced it out over the course of a few days. During this time, we were extremely surprised to discover the case shirking: wood requires seasoning (drying out) prior to working with it, it shrinks during this process as the moisture content reduces; a fact we were unaware of.

Fortunately, our plan had always been to finish the case with an oil, so we quickly started this process in the hope that it would cause the wood to expand a little, while also serving to reseal it. For this we used XXX oil. The process involves a number of coats leaving a few hours in between, then lightly sanding the wood down before oiling again.

Taking the time to ensure even coverage when oiling the case

Laser-cutting a base

Many people have contributed to Anytime, and I wanted to acknowledge that so, following in the tradition of the first Mac, I thought it would be nice to include the signatures of those people who I’ve had the pleasure to work with on this project: Michael, Michi, Pavlos, and Anna. Having received my Makespace laser training, I opted to laser cut the base out of clear acrylic, complete with engravings of the ‘team’. Using Adobe Illustrator and its path XXX, it’s fairly easy to modify the DXF files exported form Fusion to add the signature paths.

The clear base allows one to peek inside and see the electronics (including one-or-two bug fixes)

Printing the feet

Since we want to allow air to flow through the clock–in through gaps to the sides of the base, and up through the holes at the rear–it’s necessary to raise the case up slightly with some feet. This has the nice aesthetic effect of making it look like it’s floating.

As with everything in this project, we designed our own, modelling them in Fusion 360, and then printing them, this time using the Form 1–a resin printer.

Resin printers print at an angle to reduce the surface area of each horizontal slide to make it easier to separate from the printing plate

The Form 1 can produce parts at an amazing resolution when you’re used to the limitations of an extrusion printer like the Ultimaker, but it’s slow and finicky. Ultimately, a collection of little holes (perhaps due to particles in the resin) caused me to turn to Shapeways for the final print.

Finishing up

We didn’t quite pull all the parts together before I left Cambridge, but we …

I would like to extend a big thank you to Makespace–especially Jonathan and Michael–for allowing me to join for just a short period of time and for making me feel so welcome. I’m very much looking forward to my next sabbatical there.

Michael photographing the evolution of the design

Documenting the design evolution

Next steps

I’ve now been living with–and very much enjoying–the completed clock for some time, but my ultimate goal is to build some as gifts. This means I need to address some of the hardware issues before getting more PCB printed, and improve the software to make it easy for a less technical person to set up.