Notices by Dan Sanderson (dddaaannn@xoxo.zone)

Final verdict: I don't believe the MEGA65 case has enough plastic to support replacing case screws with heat-set inserts. Do not attempt.

I might have had a better result removing more plastic before trying the insert, and using a much lower iron temperature. Maybe if I were better with plastic I'd have more options for fixing or completing this idea. For me, I'm just going to stop here. Worth a shot.

/end

The MEGA65's injection molded plastic case is held together with three screws that go directly into the plastic. I routinely open my case for things, and also travel with it, so I wondered if I could mod the case for a more durable screw-hold solution.

I learned about "heat set inserts" and thought they'd be perfect if I could get them to work. It seemed unlikely but I thought I'd try it... 1/ 🧵

I found the right size insert nut and bolt to replace the screw. I knew this would be a one-way operation, so I started with just the middle screw. If it didn't work out, I'd still have the two plastic screws on the sides. 2/ 🧵

I figured I'd need to drill away some of the plastic, ruining the original screw hole. I have a Dremel "drill press" for light duty like this. This is the first time I've used it.

The heat-set insert involves a special tip that goes onto a soldering iron. The ones I found didn't fit my Weller iron, so I bought a Hakko pencil-style for $30. 3/ 🧵

I was immediately both pleased then alarmed at how quickly the case plastic melted around the nut. It was not gripping the nut at all in the melted state, but I was able to remove the heat and use pliers to form the plastic around the nut. The outside of the nut is grooved for this purpose. It seemed sturdy after that.

It seemed almost too easy. 4/ 🧵

I tried closing the case and driving the bolt into the new insert. It did not go in smoothly as I had originally imagined it would (and did when I tested the screw and nut alone). I quickly realized that some plastic melted into the inside of the nut.

When I tried to remove the screw, the nut popped out of the plastic and spun freely, but did not pop out of the case. The screw and nut were now affixed together and the case seemed permanently closed. 5/ 🧵

I managed to pop the loose nut out of the case. The grooves and bottom of the nut were filled with plastic, and the screw was stuck in the nut. How was I going to undo this?

Well, I do have a Dremel... 6/ 🧵

It should be clear by this point in the story that I have no idea what I'm doing. Thankfully, I knew to use eye protection. Nothing scary happened, just saying, USE EYE PROTECTION.

The cutting disc threw sparks, and it was clear as I was going that nothing was being held safely. If I had to do it again I would have braced the part vertically, as in a vice, and held the Dremel with both hands. The way it went down, there was serious risk of damage to the case, or to myself. 7/ 🧵

Anyway, I cut the bolt, cleaned up the charred bits, and now my MEGA65 is back to normal, minus the middle case screw.

Except then I noticed that the MEGA65 wasn't booting from the external SD card...

8/ 🧵

I swear to god the mainboard and SD card were nowhere near anything I was cutting or screwing. I have *no* idea how this happened. It could just be a crack from inappropriate pressure applied, but it very much looks like a gouge from a cutting implement. Seriously, no idea. 9/ 🧵