The strangest mod I've ever done

[Derry]

So a while back, I got my hands on a used Knopp C calcium reactor. However, I wanted to use a pH monitor inlined with the reactor to control the CO2 flow instead of playing games measuring the effluent manually. I bought a bulkhead specially designed to hold a 1/2" pH probe, only to find out that the top of the reactor isn't large enough to fit said bulkhead. Well, Jeremy (aka, offroadodge) suggested that I use a 1/2" John Guest fitting in a T off of the reactor to mount the pH probe. Problem solved!

Well, almost... See, Knopp is a German company, hence the PVC on the reactor is in mm, not inches (see pic #3), with a 16mm outer diameter to be precise. Being the stubborn type, I grabbed the trusty calipers and measured the inner diameter of good old 1/2" PVC. Turns out, the inner diameter is NOT 1/2", but rather 5/8" (uh, sure...). Doing a quick conversion, I discovered that 16mm is just .005" bigger than 5/8". All I had to do was bore out the 1/2" PVC a little, sand down the 16mm PVC, or some combo thereof.

After staring at a pile of various PVC bits and tools for a while, I remembered that my Dremel has these neat little abrading/sanding drums that I thought might be close to the right size. Wouldn't ya know it, but the Dremel drums were the perfect size to enlarge the 1/2" PVC for a snug fit with the 16mm PVC. You can see in the picture how the 16mm fits into a modified 1/2" collar, which in turn is glued into a 1/2" T fitting. Once the glue cures up, I'll thread the 1/2" John Guest fitting into the top of the T to hold the pH probe, and away I go!