For making suspension bush tubes (plus the top link tube).

Option A:
Get bar stock of whatever diameter, turn it down to required dim, drill out the middle to get required wall thickness.

Option B:
Use seamless tube of whatever diameter with a wall thickness of required.

Would there be any strength difference between the two options?

No appreciable difference. Only time and cost.

Infact most people use normal ERW tube and align the weld line with where the suspension tubes are welded on.

David

Not an expert, but I would say tube of correct size. Un-machined metal seams to have a "skin" on it.

My 2p, ready to be proved wrong

Well IMHO and from my 25 year ago apprenticeship/hnc I'd say the following.

Seamless drawn tube would have the grain structure of the material running in the correct direction ( Similar to a forging if you like)
Whereas a solid bar machined would have the grain structure cut through and therefore technically weakened.

But in reality either will be more than sufficient for the job

unless you have access to a cnc lathe, or your some kind of masochist, go with tube.

It would be difficult to simply drill the centre out of bar stock of that diameter and leave a thin wall, you would need to use a boring bar, which is painfully slow on a normal lathe.

Al.

Cheers chaps.

I was thinking bar stock would be cheaper than seamless tube but now I've looked into it I'm way off the mark.

Although having said that, metals4u don't actually list a seamless tube variant but on the basis the ERW stuff is way cheaper than bar I'll assume even seamless would be much cheaper too.

Anyone got an online source for seamless? My local IS&G are bound to be *the* most expensive place you've ever found although I've not actually asked them yet.

Edit to say: If I looked harder I'd find metals4u *do* list CDS tubing.

[Edited on 28/7/2009 by andyd]

Cold drawn tubes have grains aligned with the axis of the tube making them stronger in tension and compression in that axis but weaker in the other axis.
Cold drawing also has the beneficial effect of incresing the elastic limmit but not the ultimate tensile stress.

In any event suspension bush tubes aren't heavily loaded so strength dosen't come into it so ERW with the seam machined off will do the job nicely.

quote:

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Originally posted by britishtrident
In any event suspension bush tubes aren't heavily loaded so strength dosen't come into it so ERW with the seam machined off will do the job nicely.

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