Overflow glass hole saw size too big?

[Levinson]

I'm slowly getting ready to put together my new setup and the supplies are being shipped in one by one.

The bulkheads that'll connect the tank has arrived from China yesterday (I'm based in Korea and I didn't like the bulkheads sold locally),
Its size is 50 (Chinese standard, comparable to 1.5 inch in size). It was written on the product info (and from some other sources) that I'd need a hole on the aquarium 50~53mm in diameter so I've also ordered 50mm hole saw drill bit.
I tried fitting the bulkhead through an acrylic panel with a 50mm hole and the male threaded bit is a bit narrower than the 50mm hole. I'd say about 3~5mm smaller in diameter. The outer side of the bulkhead and silicon gasket is pretty wide so it's not like the hole is being exposed or anything but Is this how the bulkheads usually fit?
No holes have been drilled yet (still waiting on the tanks and the hole saw to arrive) so I can make changes if I want to. Would it be better for me to buy another hole saw that's a little smaller so it's more.. well.. snug fit?

Also, when you drill with say, 50mm glass hole saw, does the hole end up being bigger than 50mm? (due to grinding around the sides, etc) I've never drilled glass before and this would be my first.
Thanks

 

[mdb_talon]

What you show looks perfectly fine to me. As long as the flange and gasket can easily cover the entire gap even when the bulkhead is all the way on one side it should be fine. It is pretty normal to have some play in the bulkhead hole.

 

[afk-47]

the gasket should cover that no problem. I had a problem with my 75 where the holes were 1/8 off and needed to be egged. I used 2 gaskets on the rear and it doesn't leak.

https://www.reef2reef.com/threads/murdered-my-tank.821140/

 

[Levinson]

What you show looks perfectly fine to me. As long as the flange and gasket can easily cover the entire gap even when the bulkhead is all the way on one side it should be fine. It is pretty normal to have some play in the bulkhead hole.

Thanks! I guess I will stick to the 50mm hole saw then.
Though if I knew this sooner, I might've had the holes a bit smaller so there's less play in the hole.

 

[afk-47]

I used a 60mm for my 1.5" bulkheads. If you run into a leak, the BRS gaskets are super wide and will cover 60mm+1/8" egged drop :)

 

[SteveMM62Reef]

The Holes on my Tank are a little big. I was worried about “Centering,” the Bulkhead and it leaking. I went to a Hardware and bought “O” Rings, to help center the Fittings.