I did it! I cut my tank

[jsoong]

After debating & thinking & chickening out a few times, I finally did it. I cut a u-shaped piece off the top of my tank so I can create a siphonless HOB overflow.

The finaly push came when I had a minor flood last month during a power out (one of the siphon quit); so this is it, no more siphons.

I cut the glass using a diamond coated glass cutting wheel (from Lee Valley) in my Dremel. I practiced on a scrap piece of glass I had & the cutting was really quite easy. I flooded the area with water and went slowly with the Dremel, going over the line lightly & letting the tool did the work (no downward pressure). I did the cuts (a 6"x1" slot) in about 1 Hr, and my tank is still intact!!

I am modifying an old A/C HOB filter for the overflow box. I carved a matching end out of PVC pipe to go into the hole where the pump normally goes (using table top router & my trusty Dremel) as my bulkhead. I've cut away extraneous parts of the HOB, now all I have to do is to bend the front a bit to make it look pretty and silicone it in.

Testing for leaks Wed.!

 

[zacusmaximus]

I'd love to see your finished project! Try to post some pics so we can all admire your handiwork!

 

[Wallace]

Sounds awsome! Love to see picture of the finished product! Also, do you think it would be more difficult to cut a circular hole using that Dremel bit? If I can cut a round hole without too much extra work, I could simply install a bulkhead for the overflow. Possibly less chance of leaking?



W.

 

[jsoong]

Here's the final product - all siliconed in. I am letting it sit on my deck for a couple days before the fill test.

The dremel wheel I used is for cutting straight lines (or very gentle curves) only. On the net there are reports of people using a diamond coated pointed bit to make a hole in the glass. Problem with that is the bit is only 1/8", so after you drill that small hole, you have to patiently enlarge it by gradually grinding the glass off. I tried that in acrylic. It took a long time to make a 1 1/2" hole, and the result, though acceptable, was not perfect (hole slightly out of round). With the cutting wheel, I got a straight line that is true to within 1/16" or better.

 

[czcz]

What a great idea. Great job jsoong!

 

[two11devan]

Nice work! I was thinking about cutting a small hole in the top of my acrylic tank to allow for a power cord for a powerhead. Its an acrylic tank with a top built in. It has two openings in the top for feeding and access for the tank. The tank has water and rock in it but no creatures. Could I cut the hole with the dremmel or a drill and not worry about cracking the surrounding acrylic?

 

[jsoong]

depending on the thickness of the acrylic & the size of the hole ....

I've had no problems with 1/4" acrylics ... just make sure your drill bit is sharp - regular drill bit will work, but a carbide cutting bit is even better. The diamond coated bits will also cut well. You need to experiment a bit with the speed. You need a fairly fast rpm to prevent the bit from melting the acrylic & gumming up & making a mess ... try practicing on a scrap piece (any old acrylic will do - eg candy box, razor blade packaging ....)

I've cracked 1/8 & thinner acrylics while drilling, mainly because I pushed too hard, or maybe I didn't move the bit smoothly enough & causing torque. If you use a sharp tool & let it do the work at a decent rpm, this should be minimized. For a tank, I would clamp on a wood backer board to prevent loss of control when the bit plunges through - that being the riskiest time for the hole's edge to grab the bit causing a kickback & torque, possibly stressing & breaking the material.

 

[DeFeKt]

nice work mate.

Did you know... You can cut curves with one of the normal $5 rolling glass cutting tools.

Make sure you score it nice and smooth around the curve, and use the little metal ball on the end of the tool (yes thats what its for) to lightly tap along the underside of the score. It should pop out with a few strategically placed taps, and only takes about 2 minutes

Matt

 

[jsoong]

I've broken enough panes of glass using the "normal" glass cutting wheel that I'll never chance it on a tank! I've only had luck cutting 1/16" thin glass with those things, anything thicker & it's 50-50 if I end up cracking the glass.

 

[DeFeKt]

odd.. never had trouble doing 1/4 glass myself.

oh well, you got the job done anyway

 

[Sicklid]

They make specialised bits for drilling acrylic. The point is sharp, long, and the twist is different than a wood-bit... If you must use a wood-boring bit, set your drill on reverse, so the bit does'nt "grab" the hole at the end. This is when most cracks happen.