Drilling hole for bulkhead in acrylic tank

[DMBillies]

So, I'm getting a skimmer and will be plumbing it externally via a bulkhead into the 270 (unless I have other good options that I don't know about). The problem is, the sump does not currently have a hole in it. So, I figured on draining it, drilling it, and installing a new bulkhead. Sounds simple, and it is, except that I'm not sure what the best way to drill the hole is.

First of all, the sump is under my tank and while I can reach the spot I need to drill, it will not be particularly easy. Second, I've drilled acrylic before and had the holes chip out some (or melt) using regular wood hole saws. In those case it was no big deal... but... the sump is under my tank and cannot be removed without draining the entire tank and lifting it off of the stand (effectively undoing countless hours of work). So if I mess up that hole I'm pretty sure I'll lose all composure...

Ideas?

 

[waynesworld]

You may be able to use a diamond bit hole bit it will melt through and should be less chance to chip the trick is to find something with small teeth. Dremel and a guide would be the other option may take longer but less chance for problems.

 

[gflat65]

Use plenty of masking tape around the hole, too. That helps cut down on the melting. It will still get hot, though (the masking tape works better for cutting sheets to size more so than sawing holes...). Don't stop once you start. I made the mistake of stopping in the middle of an acrylic sump hole addition and the hole saw locked in place. I thought I'd crack the sump getting it loose again. You'd probably render a diamond tip hole saw useless after one hole (I'm thinking the glue would fill the diamond tip), but it would probably give cleaner holes. Good luck.

 

[luckyfish]

Another option would be to use PVC pipe and build an inverted U over the lip of the sump to the pump but that would be 3 90 degree turns and really decrease the pumps efficiency.