I have two 500mm lengths of half inch aluminium tube. I need to convert this into four 250mm lengths of 12mm (exact) diameter and an M10 male thread cutting on one end of each tube for approximately 15mm in length.

Are there any engineers on here with access to a lathe that could do this job for me?

Phil

Wouldn't it be easier to just get some 12mm ali tube from say B&Q and tap an internal thread down the end and then glue in a bit of cut down threaded rod?

Just an idea, cheers Rich

Tony Green top of cliff hills

Hi

Have 2x500mm lengths

Want 4x250mm lengths

Need a method of cutting without removing material

Sorry just feeling pedantic

Mick

how thick walled is the tube if you want an m10 thread cutting on a 12mm od?

If I've calculated right, it needs to be at least 2.1mm wall thickness to allow for an 8.5 pilot hole to suit an M10 x 1.5 thread.

It will end up with only a 1mm wall thickness.

[Edited on 9/8/10 by 2cv]

Wall thickness is 3mm and it's a male thread that's required, so no pilot hole needed.

Phil

I think the pipe would collapse as the thread is cut.

Paul G

quote:

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Originally posted by Hellfire
Wall thickness is 3mm and it's a male thread that's required, so no pilot hole needed.

Phil

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Looks like he wants two lengths of tube machining down to a fixed diam and am M10 thread putting on it which would be impossible . Problems lie in cutting 2x250mm from 1x500 (you have to remove material somewhere) but I suspect they're not exactly 500, and wall thickness for thread cutting - 3mm wall thickness :
3mm - .35 (trimming 1/2 to 12mm) leaves you with 2.65mm wall thickness along the length, thread depth of a perfectly cut an M10 is .92mm IIRC (larger for the more possible M12), leaving you with 1.73mm of alu to hold whatever it is holding. This may be plenty, depending on use.

[Edited on 11/8/10 by coyoteboy]

The 250mm length isn't critical but the 12mm dia is quite critical. The only grey area appears to be whether the M10 thread can be cut or not......

Phil

If you want an actual M10 thread, the nominal outer diam of the M10 thread is 10mm - if your current wall thickness is 3mm exactly and you trim it down to 12mm you're looking at 2.65mm wall thickness. To then thread that with M10 you need to machine it down a further 2mm to get to 10mm nominal diam, which gives you a wall thickness of 1.65mm. The process of cutting the thread will cut approx 1mm into the walls, leaving you .65mm. If it's cosmetic it'll probably be fine if its not holding much mass, if it's structural I'd not be betting my lunch on it. What is it holding? 15mm may not be enough to deal with the force anyway, have you run some thread engagement calcs on it if it's structural?

[Edited on 11/8/10 by coyoteboy]

OD 12.7mm with a wall thickness of 3mm is 6.7mm in the bore (12.7-6)

Then down on the ends to M10 will only leave you with a wall thickness of 1.65mm

Thread pitch of M10 is 1.5mm, so will leave you with a wall thickness of 0.9mm

So its possible, but the result wont be very strong at all and will quickly fatigue if subject to any vibration or cyclic loading.

Not quite right flak (neither was my last post) - thread depth is .866 of pitch on metric threads, leaving either .35 or .55mm wall thickness depending on fine or coarse thread chosen.

Hi

Maybe using bar would be safest if under load. Or how about making the threaded section a separate part and sleeve it in to the end of the tube.

Cheers Matt

quote:

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Originally posted by procomp
Hi

Maybe using bar would be safest if under load. Or how about making the threaded section a separate part and sleeve it in to the end of the tube.

Cheers Matt

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Hi

It took 1800Mg of pain killers ( some with hallucinogenic side effects ) and 600 mg of antibiotics to come up with the idea.

Cheers Matt