Modding Tapping Aqutube to G1/4"

I'm going to be tapping an aquatube to g1/4" threads. I've read in different places that a 11mm or 11.8mm drill bit should be used. For those that have thread tapping experience, which one should I use? Does it really make a difference? Also since I live the US a drill size would be best. I was thinking 7/16" would be good since it's the next major size down from 1/2".

 

Aqua-Computer actually sells an Aquatube with G1/4" threads now (just in case you haven't already bought one). I'll have to look up the sizes later, but whatever you do, use a drill press to drill out the holes.

 

Yeah, as Nexxo says, use of a drill press is going to be necessary to make sure you have a straight round bore into the unit so you can tap it right. Otherwise you can screw up the piece and perhaps have leaks down the road due to it looking like a blind and drunk monkey tapped your tube. God, that sounded so wrong.

 

And yet, so funny!

 

If you're going to go through the trouble of tapping the tube (lol, so many "T" words), then double check the exact hole size.

Sometimes wire gauge drill bit sizes are required for proper tapping, but according to this chart, 7/16" is closest to 11mm, and 15/32 is closest to 11.8mm.

 

Thanks for the conversion, but my concern is getting the right size bit for the tap, regardless of the measurement unit. It's just that a bit in inches would be easier for me to find. Unfortunately that chart doesn't list the drill size for a 1/2" hole

 

You said that an 11mm or 11.8mm bit was needed so that's what I was going by. Sometimes you cannot get a drill bit in inches though, but this is not one of those times.

I found a few mentions of 11.8 mm also.

Here's a pretty detailed description of the sizes and tapping requirements:

http://www.xtremesystems.org/forums/showpost.php?p=2327673&postcount=13

11.8mm bit = 0.4646 inches.
15/32" = 0.46875 inches, or 11.91 mm.

That's as close as you're going to get with an inch drill bit. I hope this helps.

 

..Which should suffice. All that would mean is the threads wouldn't be as 'deep' into the walls of the hole or whatever. Besides, it's all details. If I were you, I'd drill a 1/4" hole and just brute-force the sucker! j/k

 

It looks like 11.8mm is the way to go.

 

If you cannot get an 11.8mm bit or if it's too expensive, just go for the 15/32". The radial difference will be 0.0021", which is virtually negligible.