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StuartJPP

How To Thread 40mm Aluminium Pipe Internally?

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Trying to figure out if I can internally thread an aluminium pipe with an outer diameter of 40mm and a wall thickness of 3mm.

I somehow don't think it is going to be an easy task with my limited kit...

Any ideas/suggestions?

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I've only ever seen up to about 20mm manual threading dies, anything above that I think you'll have to go to a local fabricator.

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Yes, going to have to be lathe-cut, standard threads at that diameter will cut too deep into the thin wall.

ChrisH

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Something I just thought of....3mm wall is quite thin, you may have issues with thread depth.

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For a 1.5mm pitch the thread depth would be 1.3mm leaving 1.7mm of tube left to support what ever is being screwed into it

--

Mark

Edited by MarkyD
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2 hours ago, MarkyD said:

Lathe and an internal thread tool :)

--

Mark

Yes, that would be the way but soft thin walled tube is a pig to cut threads in especially in a "claggy" metal like aluminium. You'd probably also need some sort of external steady to stop it chattering about. How accurate and perfect a thread do you need and how precious is the tube? If something rough and basic will do and if it wouldn't break your heart if it went horribly wrong, I'd be happy to run the thread in my lathe for you. Though there are very likely better machinists with better lathes out there :)

 counterweight in the lathe.jpg

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" Lacquer Thinner ", used as a cutting fluid on aluminium will enable you to cut razor sharp, or should I say, perfect threads; a tip I learned from a Lockheed aircraft machinist.

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Right, thanks for the responses everyone...I haven't forgotten about this thread just wanted to measure everything up.

The outer diameter is 40mm.
The existing pipe's internal diameter is ~35mm (34.73mm), the wall thickness is 2.5mm.
Thread pitch is 1mm.
The length will preferably be 100mm or perhaps up to 120mm if it would help clamp it.
Threaded to a depth of ~14mm

 

OuterDiameter_sm.JPG.cb20dc84d931392d2d6

InnerDiameter_sm.JPG.0b985533cb77781f518

WallThickness_sm.JPG.78a412084eda1ebf2cc

1mmThreadPitch_sm.JPG.2d971312670e2d2b10

ThreadDiameter_sm.JPG.b4960c5957506671a5

DepthOfThread_sm.jpg.47ea0526a05889869b5

 

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21 hours ago, timwetherell said:

Yes, that would be the way but soft thin walled tube is a pig to cut threads in especially in a "claggy" metal like aluminium. You'd probably also need some sort of external steady to stop it chattering about. How accurate and perfect a thread do you need and how precious is the tube? If something rough and basic will do and if it wouldn't break your heart if it went horribly wrong, I'd be happy to run the thread in my lathe for you. Though there are very likely better machinists with better lathes out there :)

counterweight in the lathe.jpg

I will ask my "usual" guy if he can do it, not sure if he can though, very difficult to get hold of...regarding finish and such, it will be a fresh piece of stock so nothing ventured, nothing gained!

I have been eyeing out lathes and also a milling machine...I think the milling machine would come first as it would get more use, then the lathe...but I am mechanically inept...but willing to learn...better than playing Grand Theft Auto 7.

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9 minutes ago, StuartJPP said:

I will ask my "usual" guy if he can do it, not sure if he can though, very difficult to get hold of...regarding finish and such, it will be a fresh piece of stock so nothing ventured, nothing gained!

I have been eyeing out lathes and also a milling machine...I think the milling machine would come first as it would get more use, then the lathe...but I am mechanically inept...but willing to learn...better than playing Grand Theft Auto 7.

A Vertical Slide attached to the Cross-slide (plus a lathe first of course) gives you some milling capability without having to buy both lathe and milling machine.  I made all sorts of milled bits on our Myford ML7 this way for years.

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