Is there an accepted way to lay out ERW for the chassis? eg welded edge up (except for the verticles)

Or does it not matter, provided that what you do on the left, you do on the right?

There's probably a sensible answer on the way, but do you think you need to get out more?



Cheers

Chris

When it's painted nobody will know which way up it is, left to right upside down or back to front doesn't matter.

Great - wasn't sure if, when loaded, the tube would favour (not sure that;s the right word) one side and deform unevenly.

I'm laying out my chassis bottom rail today for welding

I'm not an expert but...

If you imagine a a length of square tube being bent such that one side is in compression, the opposite side in compression and the other two at the sides. I would expect greatest strength when the welded side is either the compression or the tension side.

I hope that makes some sense.

I'd place the welded-side away from any drilling you're going to do because the weld is both really hard and thicker. If you're drilling rivet holes, it can make the drill drift and be too thick for the given rivet length.

quote:

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Originally posted by kb58
I'd place the welded-side away from any drilling you're going to do because the weld is both really hard and thicker. If you're drilling rivet holes, it can make the drill drift and be too thick for the given rivet length.

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You'd have to be using marginal length rivets for the seam weld to make any difference, not the best practise.

I've measured 1.5mm seams that make the metal effectively twice as thick. The proper structural rivet size may very well call out different lengths for a material thickness change of 100%.

If you were bending the tube in the vertical plane and in isolation the best place to have the weld would be on vertical side as it would be close to the neutral axis (the point where there is no compressive or tensile stress). However in our cars the entire chassis is being bent and thus the top and bottom tubes tend to all be in compression or tension. In such cases it makes no difference so the advice should be to avoid placing the weld line near the stress raisers that are created by the holes in the tubes or at points where brackets brakets are attached.