Building the Sweet 16 Macro Pad

I never thought I would want a macro pad but lately I realized that as a software engineer, typing ProductFooServiceBarController 3 times in one sentence is neither fun nor productive. Since my keyboard support QMK, I can just assign macros to keys in a non-default layer. This works to some extent but it's hard to memorize the mapping, especially considering the set of long words I type can change over the time. It's funny that I used to despise the F row but now I wish I had a keyboard with double F rows for work (so I can use them as macro keys). The closest thing I can find is PARALLAX – layout is not ideal to me and it seems nowhere close to GB. Until that keyboard comes to existence, a macro pad with relegendable keycaps seems the best option.

There aren't many macro pads readily available that support QMK. Sweet 16 by 1upkeyboards is a rare exception. Even better, I actually bought one in 2020 and it's sitting on the shelf waiting to be built. Up until now I've built a couple of keyboards that require soldering. It cannot be too different for a macro pad right? Well, yes and no. To assemble a Sweet 16 you'll need to solder the micro controller, diodes, switches and a reset button, all of which only require basic soldering skills. The only thing new to me is that the micro controller is not directly connected to the PCB but bridged to it via two rails, which in the end is still just through hole soldering. I have to say I came under-prepared and had plenty of hiccups.

The biggest issue I had was that I simply wasn't able to properly solder the pins of the rail to PCB. The solder just kept sticking to my iron tip and refused to flow between the pin and the metal pad. I never had such issue when soldering switches before. Initially I thought my tip wasn't clean enough but later I realized there were 2 issues: 1) the holes are smaller compared to the holes for switches and my tip is too big, 2) the contact probably has too many oxides and the rosin flux from the solder wire is not enough. But realization came too late and I wasn't able to fully clean up the solder that was already applied. I didn't give up though – I ordered a new one!

With the lessons learned from the first attempt, this time I was much more prepared. I not only bought a finer tip but also got a flux pen. For the soldering part, it still wasn't as smooth as I wanted but it was much better than the first time. I was able to properly solder everything. Yet I made another serious mistake: I forgot to install the standoffs before soldering the switches, which makes it impossible to assemble the stacked acrylic case. I tried to drill a hole on the switch plate so screws can go through but the first try yeeted the whole corner off (I forgot how brittle acrylic is). Yikes. In the end I had to glue the acrylic layers together. It's definitely not pretty but at least the macro pad itself works!

So here's a few tips for you so you don't repeat my mistakes if you are to assemble a Sweet 16. Some of them are not mentioned in the official assembly guide.

  • Use a fine solder iron tip.
  • Clean up the components before soldering or apply additional flux.
  • The switches are installed on the side printed with Sweet 16. Everything else is installed on the other side.
  • If using the stacked acrylic case, add the standoffs before soldering switches.
  • Solder switches before soldering the micro controller.
  • The chip of the controller should face the bottom. Make sure you align the pinouts before soldering it.
  • If you use the Elite C controller, 1) you don't need to solder the reset button since it has an integrated one; 2) it's not pre-flashed with keyboard firmware so you'll need to flash the firmware yourself – I used the sweet16 v1 VIA firmware and it worked seamlessly.