Aerospece grade aluminium tubing

[Jolyon de FossardParticipant @jolyondefossard98326]

Hi everyone,

I have am looking for some aerospace grade aluminium tubing. The property I'm looking for is a good stiffness/resistance to bending to mass ratio. Don't care about weldability or machinability as I have to do relatively little to it in reality.

The grades that that I think are suitable are 6061 or 7075

I need a 10mm diameter tube with a 1mm wall thickness and I need about a metre of it.

Please can someone advise me of a place where I can buy more specialist grades of aluminium tubes such as these.

I am in the UK.

Yrs,

Jolly

[Jolyon de FossardParticipant @jolyondefossard98326]

[EmgeeParticipant @emgee]

Hi Jolly

Have you considered 6082 T6, following copied from the spec sheet.

"Alloy 6082 is a medium strength alloy with excellent corrosion resistance. Alloy 6082 has the highest strength of the 6000 series alloy. Due to the higher strength of Alloy 6082 it has replaced Alloy 6061 in many applications. Alloy 6082 is typically used in highly stressed applications, Trusses, Bridges, Cranes, Transport applications, Ore Skips, Beer Barrels, Milk churns."

Emgee

[richardandtracyParticipant @richardandtracy]

You are unlikely to find much extruded section from 7075. 6082, instead, is available in quite a few sizes. Go for the T6 or T65xx temper.

Regards

Richard.

[Old SchoolParticipant @oldschool]

Model yacht masts in aluminium might be suitable.

[not done it yetParticipant @notdoneityet]

I would suggest you search out aero kit suppliers if you require this material for anything that lifts a human off the ground and into flight. It will likely require all the certification that goes with aerospace usage.

[Trevor Crossman 1Participant @trevorcrossman1]

Hi Jolyon, I would suggest go to your nearest Smith's Metals who may not have in stock of the high strength aerospace alloys such as 2024 & 7075 at the branch but do hold it at their main warehouse, so you may have to make a minimum purchase of a stock length. Another stockiest is Wilson's though you'd probably have to approach your local engineering business to get it for you on their account as I don't think that Wilson's do retail sales.

Trevor.

[BazyleParticipant @bazyle]

Sounds like a model aircraft main spar stiffener for an old design. Probably now replaced by carbon fibre tube in a recent design.

As alluded to above aerospace grades aren't special magic stronger materials, they just wrapped in ten times their weight of paperwork so the people using them have to have special magic bottomless wallets.

[Cabinet EnforcerParticipant @cabinetenforcer]

Posted by Jolyon de Fossard on 10/06/2018 20:40:58:

The property I'm looking for is a good stiffness/resistance to bending to mass ratio.

There is no significant difference in youngs modulus between the various aluminium grades, so any old tat will do.

If it isn't stiff enough, change material, or change the dimensions, a diameter increase being the most effective.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Cabinet Enforcer on 10/06/2018 23:17:55:

Posted by Jolyon de Fossard on 10/06/2018 20:40:58:

The property I'm looking for is a good stiffness/resistance to bending to mass ratio.

There is no significant difference in youngs modulus between the various aluminium grades, so any old tat will do.

If it isn't stiff enough, change material, or change the dimensions, a diameter increase being the most effective.

Que? Surely 'any old tat will do' can't be good advice when we don't know what the application is!

It might matter to Jolyon. '7075' is an expensive corrosion resistant alloy with a good strength to weight ratio. This combination makes it particularly suitable for use in aircraft. But there's more – looking at the detail reveals that 7075 comes in more than one grade, with important differences. For example:

• 7075 has a yield strength of 140MPa
• 7075-T6 has a yield strength of between 430MPa and 480MPa
• 7075-T651 has a yield strength of 500MPa

Note that 7075-T651 is nearly 4 times stronger than ordinary 7075.

This is why documentation is important in safety critical applications. Work is done to specification and it's not possible to tell the difference between alloys by eye alone. In fact, an elaborate laboratory analysis is usually needed to identify an unknown alloy and its physical properties, which may have been altered by heat treatment or work hardening etc. Also, the high cost of aircraft components makes them a tempting target for counterfeiters and well organised records make fraud more difficult.

There's a world of difference between what goes in my rough amateur workshop and repairing the wing of an aircraft where strength, weight, fatigue and corrosion are all critical.

Dave

[VicParticipant @vic]

I think you’re right SOD. Didn’t an airliner crash due to an engine falling off because of a counterfeit shear pin?

[Neil WyattModerator @neilwyatt]

If you want nicely anodised 6062T and don't mid paying through the nose, you can buy a metre from B&Q. Avoid the soft un-anodised tubing, beware the bet ones and be prepared to spend ages searching.because people take them out and put them back in the wrong slots (check the bar code numbers) …

Neil (who spent fifteen minutes searching to find some rod to make a Yagi with last week)

[Jolyon de FossardParticipant @jolyondefossard98326]

Thank you everyone.

The application is not safety critical. I am rebuilding an old high quality tonearm from a 1960's hifi record player. The original tube was damaged. I don't know what it was but assumed it would be something more than the standard architectural grade. But, the tube I bought in B and Q will do. I was wondering if it wouldn't be too hard to find something better.

Yrs,

Jolyon

[Nick HulmeParticipant @nickhulme30114]

That application is begging for Carbon Fibre Tube, if it had been available in the 60s the original designer would have used it for a tonearm

[not done it yetParticipant @notdoneityet]

Ahhh, so not really an ‘aerospace quality’ thread at all. Nick’s reply above might have answered the right question at the first post.

[VicParticipant @vic]

You can buy Arrow tube in high tensile Alloy, Carbon or Carbon Composite in a variety of diameters. I think the biggest you’d get though is about 5/16” in the alloy.

[Jolyon de FossardParticipant @jolyondefossard98326]

It is not for an Aerospace application but I am happy to pay for Aerospace grade material unless the feel is that the material isn't appreciably better in terms of the attributes I am looking for.

[HopperParticipant @hopper]

"Aerospace quality" is a bit of a misnomer really. You can buy the same grades of alloy that are used in aircraft but are a lot cheaper, eg 6061, 7075 and so forth. But if you buy it without the aircraft-use certification that authenticates its origin and exact nature etc the cost is reasonable. Once you start buying "Aerospace quality", ie certified, you start paying "aerospace prices".

For what you are doing, a bit of tubing cut from an old hiking tent pole might do the job.

[David Standing 1Participant @davidstanding1]

Posted by Nick Hulme on 12/06/2018 09:53:17:

That application is begging for Carbon Fibre Tube, if it had been available in the 60s the original designer would have used it for a tonearm

Ah, but that might change the tonal quality of the cartridge, and the sound output, currently devised around aluminium, in a negative fashion!

[SillyOldDufferModerator @sillyoldduffer]

Posted by Jolyon de Fossard on 12/06/2018 11:57:13:

It is not for an Aerospace application but I am happy to pay for Aerospace grade material unless the feel is that the material isn't appreciably better in terms of the attributes I am looking for.

 

 

Listening to music is subjective. Many things influence what an individual considers to be 'good' because the experience is emotional rather than logical. It happens there's a substantial group who enjoy music more when they believe their sound system to be technically superior.

Hard-nosed engineers snigger about blinged up sound systems because they know there's no objective difference between fancy gear and much less expensive equipment. That doesn't matter. If you hear better sound from gold-plated wires and aerospace quality materials that's good reason for using them. It might be a placebo effect, but believing it works will get positive results from unnecessary technology. Something to do with the investment of time, care and money perhaps. An audiophile friend of mine had a cleaning ritual before playing an LP that reminded me of a church service and I wouldn't criticise anyone's faith.

Our brains react to both logical and emotional impulses. Our emotional side offers rich experiences but has to be treated with suspicion because it often gets us into deep poo. (Like marrying the wrong girl or voting without thinking about risks!) Spending a bit of dosh to make a sound system special doesn't feel unreasonable to me – go for it! I don't think the desire to better a sound system is any different to the equally illogical desire chaps restoring old lathes have to match the original factory colour scheme, even though colour makes no difference whatever to  functionality. That said, knowing full well the colour is immaterial, I would never paint a Myford pink!

Dave

 

 

 

 

 

 

Edited By SillyOldDuffer on 12/06/2018 13:09:21

[Jolyon de FossardParticipant @jolyondefossard98326]

Thank you all for your considered response.

The tonearm is quite rare and was an expensive item in its day. I would like to keep it looking original as much as I can so am not attracted to carbon fibre superior as it may well be in this application

The original was Nickel plated which is a strange choice really so I will be anodising the whole thing as later versions of this arm were.

So; I suppose I'll just use a nice looking tube from B and Q.

I enjoyed the comparison with a Myford restoration. As it happens I rebuilt my 1948 ML7 and used original paint but I ditched the motor and added a 3 phase machine with an inverter drive. So, it is a blend of old and new.

Yrs

Jolly

[JonParticipant @jon]

Not a Thorens is it, theyre cranked?
If bend it cold could crack or at best crinkle. If warm up to bend it will destroy the hradening and tempering.

Another consideration is off the shelf extrusions are not round externally or internally and are of a nominal sizing.
For 1/2" dia it could measure 12.9 to 12.7 plus any ovality, same with bore which is often offset.

Any thought in to the attachment in to the housing and bearing plus the catridge head, plating will add to the finished diameter.

Old materials the best for tone arms by the way, SME V is still from magnesium and for good reason.
Roksan went through extensive design and testing right down to interconnect, couple mine with an Ortofon MC2000, wired 6N purity sat on double upturned Y shaped spiked feet, sorbothane etc – unreal. The only thing thats majorly changed is the resonances, carbon you would need to start from scratch and have a very different sonic signature.

Need proper hifi to substantiate the difference between gold plated and silver plated wire. Your common high end audio setup from Currys wont cut it. For plugs its just for corrosion.
Other ways as well buy a good design and mod it for comparitive peanuts, end result comparable to off the shelf at 5 times the cost. Manufacturers use cheap diodes 10p each, caps 3p each and resistors 0.3p each, try a Vishay resistor on input stage at £10 each or Schotky diodes for regulation, Holcos resisters else where 12p each, you wont look back for the sake of £89.

[Neil WyattModerator @neilwyatt]

Posted by SillyOldDuffer on 12/06/2018 13:05:41:

Our brains react to both logical and emotional impulses. Our emotional side offers rich experiences but has to be treated with suspicion because it often gets us into deep poo. (Like marrying the wrong girl or voting without thinking about risks!)

On another forum there was an extended debate because someone had fitted (very expensive bling) tube rings to their scope instead of the supplied 'clamshell' as they felt the single-bolt fixing of the clamshell was 'risky' (it was a very expensive top end scope and clamshell).

This was met with some criticism be people who felt he was suggesting that the clamshells were unsafe.

His case that the tube rings were a sensible precaution was somewhat undermined by the fact that he felt he need to use four of them instead of two, which suggested a certain degree of over-cautiousness.

[Neil WyattModerator @neilwyatt]

To get the best from your hifi you need to have both sets of malleus, incus and stapes replaced with sintered ceramic replacements and mylar myringas.

[JonParticipant @jon]

Some element of truth there Neil the clamshell will distort the tube even if theres a thou in it.
Tubular, 2 or 4 fixing would have at least spread the load more evenly but would still collapse the tube but is the industry standard used worldwide from cheap to the most expensive.

Note the ring marks.

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