I bought a hansen tank fitting at miter10 (sftft25) - looking for a drillbit on trademe to make the hole.

Now when I put a ruler to the tank fitting (which says its 25mm) it looks about 32-33mm across the thread. The data at http://www.hansenproducts.co.nz/tech/thread/dimensions/sftft.htm#SFTF

says that for the sftft25 it is 25 across the thread. When I was at miter10 I tried threading it onto other things and the 32mm pipe adaptor seemed to fit onto it ok.

I am wondering if I actually got a 32mm tank fitting that was mislabled or if the 25mm refers to the inside or what.

Since 32mm is an actual drillsize, I was thinking that it would be the one to go for, but want conformation that I am not going to end up with a wrong sized hole that I cant use.

BTW, I will be drilling a crappy 3 foot tank first, not the good tank

from what i remember the 25mm refers to the inside diameter of the hansen fitting and you need to use a 32mm drill bit to drill the correct hole

from what i remember the 25mm refers to the inside diameter of the hansen fitting and you need to use a 32mm drill bit to drill the correct hole

Thanks for that, I had a feeling that it would be 32 but all I have here to measure at the moment is a shoddy dressmakers tape in cm.

Do you know what size the 20 and 32's take? I may as well get those bits at the same time?

Jolli is correct, pressure pipe (which is what hansen bulkhead fittings are) is measure inside diameter because that is what you would normally be interested in, i.e. how much flow will go through a diameter

i think 20mm fittings require 25mm drill bit and 32mm fittings require a 40mm drillbit

Better to have the hole too big as there is plenty of tolerance in the fitting flange.

Make a little "wall" out of putty or something around the area of the hole to allow you to fill it with water while you are drilling.

make that drill bit a 35mm. From memory a 32mm drill is slightly too small and needs to be dremeled out a bit to fit the tank fitting.

A 32mm drill bit is perfect for 25mm plumbing

Brad

just got the bit i bought off trademe, its definitly coated in something, but it doesnt feel very sharp at all, should they feel very abrasive to the hand or is it ok if its quite a dull surface when you rub it?

I recently drilled 19mm holes in a couple of my two foot tanks. The drill I used didn't look sharp but it worked.

Search for You Tube videos on how to drill a fish tank

Here is one example.....

Hope it helps

It's not supposed to be sharp because you're not supposed to be and can't cut the holes. You grind them.

Ok well it wont be till next week I get enough time to have a try but from the video it looks no problems. From the pixelated mess that is youtube it looks like the same holesaw I got (I wish more people would use vimeo of any of the other sites that dont recompress to virtually nothing)

I never thought of ebay as a source damnit.. ah well for the bigger ones I will