Cracking Acrylic from Drilling?
 

Greetings,

I wanted to enlist the opinions of those with some experience drilling existing acrylic tanks. I have a 135g Tenecor that has been up for over two years. I have about 950 watts of metal halides hanging over it in an enclosed wall/canopy. I am going to drill into the eurobrace so that i can add a closed loop into the already existing system. The holes will be for the input and output lines and i will be drilling 6 holes; 4 on one side, 2 on the other. My question is this: Is there risk of cracking? Is there a better time of day? While the halides are on? Off? Will the heat of the acrylic affect it? Is it better to drill with the acrylic hot from the lights? Wait till it cools? I obviosuly want to select the time of day when it would be least likely to crack. Let me know your thoughts.

Thanks!

how big of a hole? when I drill acrylic I use hole saws with my cordless drill that has an adjustable clutch so if thesaw should bind the drill wont btry to power through and crack the plastic. I also use the high speed.
just my .02

Maybe I'm thinking wrong here (wouldn't be a first) but your going to drill through the brace going across the top, is that correct? Depending on the size of the brace and the size of the hole that could significantly increase the strain on the remaining area of the brace causing it to crack or brake. If I'm off my mark here, just ignore everything I've already said. :D

The holes will be 1.25 inches in diameter and i should have a good 3-4 inches between the edge of the holes and any edges, either sides or near the water.

Ask this in the DIY form for the Acrylics guy. He'll tell you exactly how to do this w/o messing anything up.

hey there...
i manufacture tanks and sumps, etc...so i have a little experience :) If you use a hole saw, use water to 'lube' the cutting...it will prevent the plastic from melting, and you'll end up with a cleaner hole. Ideally, i use step bits when ever possible...greatly reduces the risk of cracking the acrylic. As mentioned earlier...drill with different torque settings may be beneficial. But in anycase, work the hole very lightly...don't use excessive force when drilling...ideally, you want to teeth of the hole saw to graze the acrylic...take a little longer, but you won't crack it. Lastly, when the bit is nearly through...you might 'wobble' the drill...this will prevent the last bit of acrylic from scaling at the end. If you have any questions, please let me know.