Hi all, I'm after some pipe tube steel to make a De Dion axel. The problem is i can't find a local supplier. First off i need to know an i asking for the right stuff, ERW Tube. Most places ain't got a clue what i'm asking for. i'm in the teesside area.
And does anyone know what sizes it is available in?

Thanks

Rob.

I would not use ERW (electrically resistance welded) tube for the de-dion axle. As you will only need around 1m anyway, I would go for cold finished seamless (usually called CFS or CDS (cold drawn seamless))

You want either CFS 3 or CFS 2 tube in either "as finished" or "normalised" conditions (these will be what most places stock anyway)

for a very small quantity like this your best bet will be metalsupermarkets, there is one in Gateshead, tel 0191 4872144. They may not carry CFS but should be able to get it in for you.

Size wise for the axle you would want to be looking at 45 or 50mm x 2.5 or 3mm, or imperial equivalent.

Also worth having a look in the yellow pages at any fabricators in your area, pop in and see them, they may have an offcut os something suitable laying about if you buy them a beer or two!

try elmdon metal in york they keep a good stock of cds and t45

regards

marc

Already got the cold rolled tube for making pinto turbo manifolds, just seems a bit heavy gauge for the job.
Will start ringing through the yellow pages on monday.
What about scaffold pipe??

what is the wall thickness of the cold rolled tube that you already have? As long as it is not over 3mm then it is fine, 45mm od 3mm wall is only 3.1kg per m.

Why use cds anyway when erw is more than good enough.

If i could find erw pipe i'll use it as its lighter The pipe i have is 3mm wall and not light weight at all.

can get you a piece of tube if u give me length going to stoneleigh on monday can bring with me if you dont need over 52 inches long or it wont fit in boot i made my own de-dion if u want u can look in photos

I'll let you know thanks. Not sure if i'm going to stoneleigh yet. If i get the clutch changed in my RS2000 i'll be there.
Oh at the robin hood club(I'm a member), great club by the way if anyone is interested.

Rash, Just looked at your photos. Top stuff. how did you bend the pipe? I was going to cut and reweld.
Also how did the shortening of the drive shafts go need to do mine too.

[Edited on 25/4/04 by Rob Allison]

Could you use exhaust type tubing if you don't want heavy wall gauge? It's available in various diameters for different cars so one should suit.

Prop shaft tubing would be fine if you can fid a long enough shaft.

If you are after erw tube try tayside Tubes ( Marston Moor Business park )

quote:

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Originally posted by Rob Allison
If i could find erw pipe i'll use it as its lighter The pipe i have is 3mm wall and not light weight at all.

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the tube was bent in a pipe bender hudraulic type the shafts i just made two small sleeves then cut and welded not run yet though so dont quite know how it will go ?? will have to wait and see.

Thanks for the info. Just need to get me arse in gear now

Spoke to darren of GTS tuning at detling about why they use a welded tube rather than a bent one, he said something about it being a basic engineering principle that you don't stress a bent tube.

something to consider?

For a supplier try Corus metalshops in Middlesbrough. They are in the yellow pages. They deliver for a small charge. The bloke I got on the phone was friendly and helpful despite me not knowing anything about about what I was ordering and the small amounts I was buying.

Richie, Did you get you all your metal from them? I got my 25mm box tube from carter steel but its thick walled stuff.

Hi again! I would not use ERW for this job, simple as that. If you want to then go ahead, but weld it in the wrong place then twist it and it will peel open. I never use ERW in unsprung suspension components in any of the cars I have built.

As for the weight issue, if you use 45mm x 3mm CDS then you are talking 4.1 kg as the weight per m is 3.1 kg. I do not think this is a big area for weight saving.

I would certainly not use exhaust tubing! This is not structural tube and also will be nowhere near thick enough to do the job.

Bending tubes is ok for furniture,take a look at a Duke...straight cut and shut welded tubes........fastest bike in GP's........enough said i think

I wasn't going to say it Syd, as I have put enough fuel on the bonfire by saying not to use ERW (same weld problem as you mention above) But I would completely agree!! As you say, roll cages are specifically bent not welded. Many production (well, semi-production like Aston and Daf) used bent de-dion tubes, that's certainly the way I would do it!! The only benefit to cutting and welding as I see it is that it might be easier to keep the ends parallel! Having said that you can always tweak the axle in the pipe bender again once the hub flanges are welded on!

I didn't want to open a can of worms here, just find some pipe. I now have some sed 80 50mm hp gas pipe should do the job if a bit heavy though. As for bent or welded ??? each has its advantages, bent should be stronger. But i ain't got a bender. So correctly welded and braced for what i want should be ok. Hope you agree.
I have seen suspension components form kit manufactures using ERW tube. The frame of my RHE 2b is 38mm ERW tube. Don't say it i know you get what you pay for.

If you are wanting to save weight or use a high spec steel with this, it might be worth looking at T45 (slightly higher spec than Chro-Moly tube)steel from Elmdon Metals.

Its Ultimate tensile strength is twice that of CDS meaning you can use thinner wall sections. This is the material that is used for World Rally Car roll-cages and is very very strong for its weight...

It also needs no treatment after welding.

[Edited on 26/4/04 by imull]

Sorry to divert the thread again, but the mention of "T45" tube prompted me!

As Imull said it is very strong, so very thin sections can be used, and for a locost probably an "ultimate" construction material. A few words of caution though.

Chrome-Moly (4130) tube does need care when welding, it is prone to embrittlement and can crack very easily around heat affected zones (this is why often 4130 struxtures are stress relieved after welding)

Interestingly, I heard that although a leading rollcage manufacturer supplies T45 cages, it's proprietor does not use them in his own racing cars (National GT's) as they are susceptible to failure in multiple rolls. He used standard CFS tube.

The point made was that though the T45 was much stronger at the first impact, it work hardened and cracked and then fractured at a second or third impact, whereas the standard CDS, though weaker, bent several times without cracking. thus preserving the structure of the car better.

All this said, the consequences of an accident of this level of severity in the type of cars discussed on this forum would be pretty much irrelevant anyway as the structure of the car that the cage is attached to would fail anyway!

Second point is that to comply with MSA rules, if you are building your own cage, the material must comply with the MSA minimum thicknesses anyway which makes no discretion between T45 or normal CFS.

Just to point out that there are two sides to every coin!

Nat.

Ah interesting as i have an escort that i'am going to space frame for sprint/hill climb use and T45 had been mentioned, but hard to weld.
Looks like CDS then.

Surely as long as the diameter is big enough to ressist significant bending and the thickness enough to prevent buckling it dosen't matter if erw or dom is used --- look at a standard book Locost Escort English axle it is paper thin mild steel and while the banjo stiffens it in the middle surly beam bending isn't that big a factor.

Yes, you are right, but not as simple as might be thought. ERW is welded, obviously, and so has a heat affected zone (usually visible by the temper colours). This will affect the fatige life (and probably the ultimate strength but I'm no expert on this) so as long as the tube is sized as a welded structure and not a full round tube then all is ok, but the weld weakens it significantly, especially if you feed stresses into it right next to the weld line.

Rob, one of my previous projects was a semi-spaceframed rear wheel drive Peugeot 205, I'll try and find some photos and put them in my archive. I used normal CFS (CDS) for this, and you may as well because as I said, the main cage elements, if built without a "manufacturers certificate" must be to the min. sizes in the blue book which are 38x2.5, 45x2.5 or 50x2 irrespective of T45 or CFS (CDS). (ok, you can use thinner but you have to get it fully stress tested which is not very easy!!)

quote:

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Originally posted by Rob Allison
Ah interesting as i have an escort that i'am going to space frame for sprint/hill climb use and T45 had been mentioned, but hard to weld.
Looks like CDS then.

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Yes it can be awkward, best to "anneal" the area to be bent first (not strictly annealing! warm area to dull red with blowlamp and allow to cool before bending, work hardening during bending recovers properties again!) This prevents the kinking!

I have built 2 cages using the spec though, one of which was in a car rolled on at least 5 separate rallies, and although it had to be repannelled a few times the cage never moved. (we had a jig to check it!)

I would never say the spec is over the top!!!!!!!!!!

I have seen several cages to blue book spec broken clean off at the a-pillars after serious rolls. A lot of the bits for my Pug came from a RWD Fiesta with mainly 38mm cage, which had folded the cage in two at the a-pillars. I would never use 38x2.5 in a saloon car now, I use 45x2.5 as a minimum. The forces on the cage during a severe crash can be absolutely massive, on one occasion enough to snap cleanly through 4 pieces of 10mm thick dural plate holding the seat to the mountings.!!!!

[Edited on 26/4/04 by NS Dev]

Guys, while you are reducing wall thickness to save weight while maintaining strength due to an alloy upgrade, you are reducing stiffness. On an item that sees bending loads like a De Dion tube I would have though this to be quite undesirable, so an increase in outside diameter of the tube will be needed to maintain stiffness. Also, buckling effects may have to be considered...in other words a significant redesign to take advantage of the new material.

Sorry to jump in and ruin a very interesting thread but .....

quote:

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Originally posted by NS Dev
what is the wall thickness of the cold rolled tube that you already have? As long as it is not over 3mm then it is fine, 45mm od 3mm wall is only 3.1kg per m.

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Hit the nail on the head!!!!!! Quick formula for anybody else wanting to work out steel tube weight is:
Kg/m = (OD - Wall) x Wall x 0.02466

Dev, very interested in the photos. (off topic but i started so ) As i need ideas on doing it. Not sure if i should get rid of the inner wings or keep them? My basic idea was to fit a locost type chassis where the floor was ??

There is 1 pic of the pug from the back in my photo archive now. If you U2U me your email address then I will send you more photo's and also more info.

Basically if I did the job again I would remove the complete floor/bulkheads etc and mount everything to the cage. If you go on www.beardmorebros.co.uk and look at the V8 reliant Kitten project you will see how I would do it now!

[Edited on 27/4/04 by NS Dev]

Nice job Dev. Looks just like what i'm after doing. u2u sent

It isnt so much that T45 is stronger, it has more attractive properties.

It has a yield strength of approximately 680N/mm^2 compared to the 350 specified in teh blue book for CDF/CFS

This means that it will not permanently distort, until almost twice the stress (Force/Area) is applied.

Obviously, this means tha tyou can lower the area without it failing the tests.

I am surprised to hear Martin Short doesnt use it, as I spoke to his company at long lengths a year ago when starting my dissertation on this subject. They never mentioned that he doesnt use it

The MSA will accept calculations for the roll cage testing from what I can figure (no such thing as a straight answer from there ) so it is not necessary to create a test structure first.

As others said, it is very rarely the first impact that does teh actual damage. It serves to weaken the vehicle in one way or another.

At the end of the day, this is your life we are talking about and if you can afford the extra cost, you would be wise to go with the highest spec steel that you can afford. That doesnt mean that you have to reduce the thicknesses to suit!

If nothing else, the chassis should withstand the odd bump slightly better...

I hasten to add, Martin Short did not say Rollcentre does not use T45, he said HE does not use T45 on HIS racing cars. (Maybe he does now, this was 2 or 3 years ago)

PS IMull, if you have been in touch with the rollcage manufacturers, did you get the chance to see Safety Devices' facilities!! WOW!! Their CNC tube cutter/profiler and CNC bender would definitely be on my wishlist!!

misunderstood what you were saying about his cars.

I spoke to Safety Devices quite a lot. Very helpful people in sales. Unfortunately, when I wrote to Tony Fall on more than one occasion regarding using their coordinate geometry machine, i didnt even get a reply saying no...

Not really felt inclined to spend more time on that avenue. I approched other companies including one world rally team who have been more helpful than I ever hoped!

Have been told that their set up is awesome though.

On the same topic, does anyone know a decent tubing supplier in the Brighton area???

Olly,

Send a u2u to Jasper- he's not far from Brighton and has been driving his car for a year. Should know the best places around you.

Good to see another Southern builder!

Make sure you come to the Newlands Corner (just outside Guildford) meets 1st Sunday of the month.

Cheers,

James

Cheers for that James will do!

Only partly based in Brighton as i'm currently studying up at Brunel Uni, but the plan is to start building the chasis over the summer months. Hard life being a student, only 4 months off!!