Tuesday, October 6, 2020

[M3, Skyline] Cutting mirror glass, misc. car stuff

[note: this post, like an air-cooled 911, is back-dated to when these events occurred] 

Plan B complete.

I bought a glass cutting tool and shipping from Latvia was surprisingly quick. To cut my convex glass, I had to pry it off of the E30 mounting plate. This is done easily with some plastic wedges, as they're secured only with double-sided tape.

Just have to make this look like that.

Thankfully I caught this error before I got started... I was about to mark and cut the pattern backwards, onto the wrong side of the glass.

Some tips from a glass-cutting newbie. There's nothing particularly tricky to it. You buy a glass cutting tool, which is really just a tiny diamond-tip roller on a handle, apply some cutting oil, and score the glass in the desired shape. Then you tap the glass lightly to get that score to fracture through, and it breaks apart along your line. When the glass wraps around corners, to make this fracture easier, you want to score some relief lines to make it break into smaller pieces. I practiced on spare junk glass to get a feel for the scoring pressure and technique. Not motivated to buy dedicated "glass cutting oil" I used tapping fluid, which appears to have worked fine.

My first attempt did NOT go fine. Trying to keep the shape faithful to the original, my plan was to leave the template glass in place and score around it, using the edge as a hard guide. Unfortunately this did not allow me to score hard enough. As you can imagine you don't want to have to stop-start your score, if it can be avoided, and it's hard to go back over something precisely if you didn't go hard enough the first time. I feebly put in some relief scores and you can see that it was a total failure. It fractured right through the glass. Well, this is why I bought 3!

For the second successful attempt, I just traced the original shape and then cut free-hand. I didn't get the ultimate control I wanted, but I focused on keeping it continuous and getting a good score through the glass. 

From here it was a lot of sanding to get the final shape and check the fit. I used a Dremel to knock back the larger areas but found that it had a tendency to chip away the reflective coating on the glass that makes it a mirror. It would take little half-moons along the edge out pretty quickly so I went back to hand-sanding. A 150-grit dry paper was the sweet spot for removing material without putting too much heat into it or chipping the film. From there you can wet-sand and go to finer grit to your preferred level of finish. I found wet 250 was fine and softened the edges nicely.

Final verification will have to wait for when the car's back but I'm very pleased with the result. Score one for the DIY guys. I was encouraged enough by the outcome that I ordered some clear tail lamp lenses from eBay and will embark on a faux Startec project when they arrive.

While I wait for the M3 to come home, here are some other covid car adventures.

With movie theaters closed, the (sole remaining) drive-in theater in San Jose seems to be doing a good business. We saw Tenet. For $17 for two it's a good value, the Model 3 has a nice sound system, and it's fun to watch in your own little private 'room.' Picture quality obviously isn't going to compete with IMAX - I'll have to see this movie again properly at some point - but we had a good time!

Spotted my first new Defender in the wild. Neat. Finally, I've been using the GT-R to scratch my driving itches. Cars and Coffees are starting to re-emerge so it's been making the rounds.

It's always a big hit with my fellow youths...