I'm in the planning stages of replacing my RS reefer 300 and am thinking of having an acrylic tank built that will fit the stand then adding an external overflow so I can reuse the stand and sump. I've drilled glass a couple of times but never acrylic. What is the best way to drill acrylic? I've read of heating a pipe to using a wood hole saw but I would like recommendations from those of you with actual experience please.
The best way to do it is to have the tank builder do it.
I just went through this a couple months ago myself, and in hindsight I really wish that I had done it that way.
If you go down that route, decide on your overflow first, physically buy it, and measure the holes you need. Then provide that information to your builder and have them drill it to spec. If you want to do it yourself even so, I'll tag in
@UncommonSense to add on to what I'll say.
First, tools. I used a hole saw, and that worked... fine. The big problem with a hole saw is that you cannot use the diamond-coated hole saws that most external overflow kits provide. They're designed to grind through glass, but all they really do on acrylic is clumsily melt the plastic. I drilled through two full batteries with a diamond saw and didn't even make it through 2mm of material.
So yes, you need a regular wooden saw, with a proper pilot bit (the other reason the diamond-coated saws aren't good). The next problem is heat. Cutting through the acrylic generates a lot of heat, and what tends to happen is you cut out some acrylic, it melts, and then it cools down over the teeth of the saw, so you can only cut for a little bit before your teeth are jammed up with melted acrylic. So you need water to keep the heat down and prevent melt, and you need to stop occasionally to clear out the teeth.
Other than that, resist the urge to press down on the drill as you cut. Let the saw do the cutting - you don't want to flex the acrylic. Go slow but not too slow. You also want a bit of torque - on my Ryobi 18v drill, I had the torque selector around setting 15.
Start from the back end, cut down about 50%-75% of the way through the material. Once you've done that, start the cut from the opposite side, using the pilot hole from your first cut to guide your cut through.
I got my tank from Tsunami, and they were great. If you have them apply a vinyl background to your tank, be aware that they actually sandwich the vinyl between the back wall of the tank and a very thin sheet of acrylic in front of it, so you don't need to worry about cutting the vinyl away when you drill.
I've heard that a step drill would also work, though I'm not sure I believe that for a hole the size of a bulkhead. You can find step drills thick enough for it, but they are expensive and unwieldy.
If you go for the Eshopps overflow, be aware that the provided drilling template might not play nice with the kind of hole saw you need. For the size I used, the holes of the template were 60mm (exactly), which is
almost but not exactly 2 3/8". That makes the template basically impossible to use for an acrylic tank, but it's enough to just use it for a rough start. The bulkheads between your tank and the external box actually have a bit of play to them, so you don't need an exact fit for it to work.
www.reef2reef.com
