Zum Inhalt der Seite gehen


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/ 🧵

teilten dies erneut

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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/ 🧵

Venty 🇨🇭🫕 hat dies geteilt.

Als Antwort auf Dan Sanderson

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

Als Antwort auf Dan Sanderson

I wonder if you could use epoxy to build up the area around the insert. Maybe Loctite epoxy plastic bonder or similar?
Dieser Beitrag wurde bearbeitet. (1 Monat her)
Als Antwort auf Mark Krueger

@markkrueg Worth trying, yeah. If I just want the original screw terminal back I might get away with a dab of hot glue. :)
Als Antwort auf Dan Sanderson

A night’s sleep and a new SD card later, and I can diagnose the broken card. I see a plastic support right where the card breakage occurred. It’s possible that the board was mis-seated and this support jutted into the passageway, cutting the card when I tried to insert it. The passageway still feels partially obstructed and the card isn’t reading. Looking more closely now…
Als Antwort auf Dan Sanderson

Unfortunately in trying to fix what seemed like an obstruction in the slot, I think I bent a pin or something. The reader no longer works, and I'm not sure I can fix or replace it.

Lucky for me the MEGA65 has two SD card slots, and I also have a spare board. That's what I get for taking an interest in hardware. NO REGRETS. 😎

Als Antwort auf Dan Sanderson

That is definitely the right attitude to get anywhere in hardware!

I broke and almost-broke quite a few of my early computers but gotten more careful with time. Yet, I think I would be a lot more skilled by now in electronics if I were as unafraid to make mistakes as I was back then. Instead, I work in software.. 😹

Personally, joining a local #RepairCafe has really helped me: no risk in breaking something that is already broken, you can only win! 😹