the tube cracked during cutting, lol. That's why I use the precision mitre saw for it...gets very close to perfec, then I use a light sanding pad on the dremel to square it up as close as I can.
To keep the tube durable I flame polish the acrylic

it leaves the whole
tank crystal clear and eliminates any area for stress cracks to appear as a result of the cutting/sanding process because everything is glass smooth.
I have no problems after they
tanks are made, just that using the pipe cutter generates too much stress in the wrong direction (I can see it is cracking in the same direction as the extrusion....i may just be too impatient and tightening the cutter wheel too much between passes as well. I'll take pics of a few finished ones later so you can see the effects of flame polish vs sanding if you want