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Author: Subject: The tubing to use in an old Dural AU4G design
FlyBoyBC




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[*] posted on 11-20-2017 at 06:49 PM
The tubing to use in an old Dural AU4G design


Hello! I am working with the following design:

http://home.caiway.nl/~fnijhuis/zeki.../sb_buggy.html

It uses Kee Klamp railing fittings and Dural AU4G tubing in the following dimensions:

5 m tube 35 x 31 mm (chassis, frame, front fork) 1.38in
0,60 m tube 35 x 25 mm (central frame tube)
0,50 m tube 30 x 26 mm (used for reinforcements)

Dural is an obsolete trade name described as an aluminum and copper alloy used in aerospace because of its high resistance to stress and its lower density than steel .As a result of various evolutions of the designations and standards, it was then called AU4G (Standard NF A 02-104), and from now on 2017 (Standard NF A02-004 / EN 573-1)

From this I gather that 2017 Alu/alloy tubing of the above dimensions should be exactly equivalent to the original but when I search for 2017 tubing it seems like it basically does not exist. I can only find 2017 in rods and wire.

I looked at 6061 T6 seamless tubing and can only source 1.375 X 0.058 locally which is thinner than the 35 x 31 mm called out in the old plans but I don't know if this is even a valid comparison.

All I really need to know is what tubing material can I find that is between 1.31in and 1.38in that has similar mechanical properties to "Dural" in the above sizes? I hope for the corrosion resistance of 6061 T6.

I would certainly consider using 1.375″ OD x 0.049″ WALL x 1.277″ ID Seamless Stainless Steel 316 Round Tube and


1.375″ OD x 0.065″ WALL x 1.245″ ID Seamless Stainless Steel 316 Round Tube as I can source it locally.

As you can tell I know nothing about the subject. I can WORK with metals and I do nice work but this old standard has got me stumped.

A little help?
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indigo_wolf


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[*] posted on 11-20-2017 at 08:09 PM


The link you provided for the buggy was abbreviated and got broken in the process. It took me a while to expand and correct the link to:

http://home.caiway.nl/~fnijhuis/zekitez/buggy/sb_buggy.html

Ironically I was just looking at this buggy on Popeye's website earlier this morning (waaaaay earlier).

OK, let's see if we can suss out a bit more about your question.

<* Insert appropriate sound effects here *>



ATB,
Sam




"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King
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indigo_wolf


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[*] posted on 11-20-2017 at 08:45 PM


I think your next stop might be

Maryland Metrics. The site touts itself as:
"The One-Stop Source For Metric And British Sized Fasteners, Wrenches, Cutting, & Measuring Tools, Metal Shapes..."

https://mdmetric.com/tech/alumcomp.htm

Unfortunately their website is a bit of a throwback to the 1970s-80s and is a bit of a PITA to navigate.

You might have better luck calling their 800 number in the morning.



Given them a holler, if they aren't a direct solution,

Apparently 2017 is now 2017a and it carries a different name under:

ISO - Al-Cu4Mg
Canada - 17S
France: A-U4G
Germany ( DIN 1700) - AlCuMg1
Germany ( DIN 17007) - 3.1325
Great Britain - H14
Italy - P-AlCu4MgMn
Japan - A2017

ATB,
Sam




"I never had any friends later on like the ones I had when I was 12 - Jesus, does anyone?" - The Body by Stephen King
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FlyBoyBC




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[*] posted on 11-20-2017 at 09:05 PM


All I really need to know is what tubing material can I find that is between 1.31in and 1.38in that has similar mechanical properties to "Dural" in the above sizes? I hope for the corrosion resistance of 6061 T6.


Basically "what is used instead of Dural tubing now"?
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FlyBoyBC




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[*] posted on 11-22-2017 at 05:15 AM


After some intense reading and comparing and thinking about it I have tentatively concluded that 6061 T6 seamless tubing with a slightly thicker wall may be equal to this old "dural" standard but I have not finished my analysis yet.

I have found it very difficult to find any information on "dural" and this "AU4G" standard.

I have also been thinking about trying fairly thick CF tubing 53mm dia by 3 to 5 mm thickness. The torsional load transferred to the frame from the swanseneck is held by a bolt going through the entire joint. I am not sure how well this would work with CF.

For $100 I can get a 1 meter long piece of 35mm x 25mm CF on ebay. That is exactly the length of the axle of the "Slow Brain".

Do you suppose CF tubing epoxied into the Kee Klamps would work? I have seen railing systems put together in exactly this way but would it be as strong as this Dural stuff? Most information seems to indicate that it would be vastly superior but I have never seen anybody build anything bigger than a quadcopter using CF tubing. No go-carts or minibikes made from CF tube out there despite the glowing statements that it's twice as strong as aluminum of the same dimensions. People chop bike frames apart and replace the straight sections with CF tube and use the original bike parts to join the tubes together. This is fairly similar to what I am proposing. It works for bikes......

If I just blindly believe that then I should be able to clamp and glue 35x25 and 35x29 CF tubing using Kee Klamps and end up with something stronger and lighter than the original.

I would hate to spend all that money and time only to discover it is too brittle or something...........
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