Hello all,
I have some 60mm, 3mm wall thickness ERW tubing which I'm using to make the main de dion tube with.
Are they different qualities of ERW tubing available? this stuff seams very poor, no matter how I blast the weld into the tube, it seems to just sit on the top 1mm rather than good pentration, the other stuff I'm welding to it is virtually melting at this power.
I'm fairly certain it's not the welder as it can weld everything else absolutely fine

Confused from Chandlers Ford
David

Tell me to shut up if this is obvoius, but has the tube got any coating on it that might be hindering the spark? Have you tried going over it with a wire brush first?

Sorry I forgot to say, I took the scale off with a flap disk

Cheers
David

Have you tried pre-heating it a bit, I had to do that with some of the thicker materials in order to get good penetration at the beginning of the weld?

Cheers

Alex

Have you welded 3mm thick steel before? Hot-rolled? Is your machine's up to it?

"The weld seems to sit on top of the material," is an indication of either too little heat or surface contamination.

Hot-rolled steel has a very tough, baked scale on it, so you need something tougher than a wire brush. The metal should be very shiny before welding. I use either a grinding wheel or a motor-driven sanding wheel.

I try to stay away from hot-rolled steel for this reason.

[Edited on 2/26/07 by kb58]

I have one of these welders, it's a very powerful welder even on fairly low settings it can heat metal until it's glowing

http://www.weldinggear.co.uk/Mig-Welders/MUREX-TRADESMIG-210-1-MIG-WELDER-PACKAGE_569.htm

I was a welder by trade in the shipyards, I've been welding for 25 years, the thickness plate I have welded was 20 inches thick, not with my welder though!

It must be surface contamination, that's the only thing that makes sense, I used a flap disk, and the metal was sparkling. I can get stuff blasted cheaply, maybe I'll do that or I could get some 2.5" CDS tubing

Thanks everyone for your thoughts

Cheers
David