I have been chugging away on Project Nautilus despite the Holidays. Those of you keeping up know I’ve been installing a “window in window” mod on the side panel. One of the obstacles I faced was, that in order to center the inside window, I felt it was best to mount the acrylic to get the measurements right and cut it while mounted. Another problem I faced was that I dropped from 1/4 inch acrylic to 1/8 inch because of clearance issues.
So, I mounted the acrylic up to the side panel window using Scotch/3M “Red Super Tape” (RST). RST is amazing stuff. It’s obviously made with some alien technology acquired in Roswell by 3M. Once you tape an acrylic window up with RST, consider it permanent.
I measured out to get the center mark of the window for my next cut. I grabbed my 5 inch (127mm) monster hole saw, put some tape over the cutting area, clamped the piece down, pre-drilled the pilot hole, and I was ready to cut.
Usually when you want to cut acrylic with a hole saw you clamp a sacrificial backing to the piece (a piece of plywood or scrap acrylic). This stops the acrylic from flexing and the saw from grabbing - both of which will crack an acrylic piece. I didn’t really have that option as the piece was mounted to the side panel and there is a gap. Still, I have cut plenty of 1/4 inch acrylic without a backing and without cracking.
The moment the saw hit the acrylic, I knew I had a problem. The weight of the drill alone flexed the material. This is 1/8 inch - not 1/4 inch acrylic.
I turned my personal skill dial to “11”. I knew if I made the cut slowly and if the saw didn’t grab, I would be fine. The cut took well over one minute before starting to break through on the back side. Right at the end the saw grabbed and flexed the acrylic slightly just as the cut finished and the “blank” dropped. Not a big deal, the cut looked fine - with tape around it.
I removed the tape and found the result of that tiny flexing. A nice little crack was created; ready to propagate all the way through the acrylic. I drilled a little hole to prevent it from spreading its plastic disease (the haze in the image is from the protective coating). It won’t show because it will be covered by a piece of brass, but I will have to fix it eventually - I know it’s there and it will drive me nuts.
Lesson (re)learned: Use a sacrificial backing when cutting through plastic/acrylic.
Good news: Well, I should have made a template for this cut – now I have the cracked piece to use as one.
Bad news: In order to get said template I will have to somehow pry it loose from the alien death grip of the Red Super Tape.