I just bought two 3/4 inch bulkheads, but they wont fit in the hole. The threaded part on the bulkhead doesnt go through. How can I make the hole slightly bigger. Its a glass tank and 1/4 inch thick. Thank you

Dremel + diamond bits + water.

2x

Take one of your bulkhead O ring's. And with a fine point sharpie trace the center of the O ring over the hole that you drilled. Because you need a pattern so that you don't end up drilling a oblong hole. Next drive over to the hardware store and buy a 20 pack of Tool Shop diamond coated bit's. They only cost 8 dollars a 20 pack now at Menards so go ahead and buy 2 pack's of them. Put the cylinder bit into your dremel and run cold water over the hole. Work the cylinder bit in a up and down motion. And you will end up with a nice smooth finished hole. Take your time and let your dremel cool off every 15 mins. It's going to take you a while to get the job done using your dremel. Because your tank is made out of 1/4" glass. Enjoy

shouldnt take more then 5 min with a dremel....i made a 3/4" bulkhead hole large enough to fit a 1.5" bulkhead in about five minutes..and that was with the tank full of water..

i used a spray bottle to mist the bit and glass..

This is old but what dimond bit do I need to do this . Does wallmart have these bits.

Yes, Walmart carries them for ~$7. You can find them in the isle with other drill bits and power tools. There should be a little rack specifically for dremel bits.

They come in a two piece set. One bit is a ball bit and one is a wedge. Use the ball to start a new hole and use the wedge to do the whole grinding.