Tapping Aluminium Tube ?

[The Coal Man]

Hi,

Would anyone please be able to advise me about tapping some aluminium tube with an M10 thread?

I have some tube that is 14mm O/D, 8mm I/D and 3mm wall. If I were to try to tap it by hand with an M10 thread, do I need to increase the size of the inner diameter to 8.5mm with a tap drill before attempting to tap the thread?

Looking at tapping sizes, a tapping hole of 8.5mm is recommended for an M10 x 1.5 thread and I wondered if I can get away without having to drill out the 8mm hole to 8.5mm for tapping the thread.

My other option is to look at tapping an M9 x 1.0 thread for which the recommended hole tapping size is 8.0mm. However, I am not sure if threaded rod or bolts are readily available in M9 x 1.0 thread?

If there is an imperial option close to my sizes, preferable closer to 9mm than 10mm then I could possibly look at that?



Thx

 

[gordon stephenson]

You will have to open up the bore to the correct tapping size to get a good start, And use some lube.

 

[Rig Pig]

Just run a drill up it.

 

[slimjim]

If you havnt got a 8.5mm drill, then file the 8mm hole out a bit,

It will only take a minute,

It doesn't need to be perfect, but it needs to be nearer than what the 8mm is

 

[The Coal Man]

Thx for the replies.

I will either drill the hole out or tap it with a 3/8" UNC thread which requires no enlargement of the 8mm hole