richms Posted September 6, 2008 Report Share Posted September 6, 2008 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 Quote Link to comment Share on other sites More sharing options...
jolliolli Posted September 6, 2008 Report Share Posted September 6, 2008 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 Quote Link to comment Share on other sites More sharing options...
richms Posted September 6, 2008 Author Report Share Posted September 6, 2008 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? Quote Link to comment Share on other sites More sharing options...
suphew Posted September 6, 2008 Report Share Posted September 6, 2008 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 Quote Link to comment Share on other sites More sharing options...
jolliolli Posted September 6, 2008 Report Share Posted September 6, 2008 i think 20mm fittings require 25mm drill bit and 32mm fittings require a 40mm drillbit Quote Link to comment Share on other sites More sharing options...
WEKA Posted September 6, 2008 Report Share Posted September 6, 2008 Better to have the hole too big as there is plenty of tolerance in the fitting flange. Quote Link to comment Share on other sites More sharing options...
WEKA Posted September 6, 2008 Report Share Posted September 6, 2008 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. Quote Link to comment Share on other sites More sharing options...
Rockerpeller Posted September 6, 2008 Report Share Posted September 6, 2008 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. Quote Link to comment Share on other sites More sharing options...
Freakyfish Posted September 10, 2008 Report Share Posted September 10, 2008 A 32mm drill bit is perfect for 25mm plumbing Brad Quote Link to comment Share on other sites More sharing options...
richms Posted September 26, 2008 Author Report Share Posted September 26, 2008 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? Quote Link to comment Share on other sites More sharing options...
Smart Guy Posted September 26, 2008 Report Share Posted September 26, 2008 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 Quote Link to comment Share on other sites More sharing options...
Ira Posted September 27, 2008 Report Share Posted September 27, 2008 It's not supposed to be sharp because you're not supposed to be and can't cut the holes. You grind them. Quote Link to comment Share on other sites More sharing options...
richms Posted September 27, 2008 Author Report Share Posted September 27, 2008 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 Quote Link to comment Share on other sites More sharing options...
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