my stays - 4 mm thick, 20 mm steel.

To strenghtnen them, I doubled up the metal at the lower part, drilled 6.5 mm hole, countersunk, then weled to the other piece (plug welding I think it is called).

I noticed that the other sdie of the metal did not change colour (showing little heat) and when I bumped into one stay, two fo the welds pinged apart

Examintaion shoed that harldy any of the lower metal was wsleded so mainly the hole was filled up in the top piece.

My welder is clarke, and is rated at 4 mm max so I presume therein lies my problem. (I am welding 8 mm thickness in total).

Any tips on how to improve this?

For exapling, dirrling the hole all the way trough and then filling up?

I won't be redoing them but will weld up along the edges of the second piece where it lies on top of the first piece.

Pre-heat the metal, with a blowtorch?

You would be better chamfering the edges of both pieces and laying a butt weld along them.
plug welding is hard with a lack of power.

Even better would be to braze them, it withstands the vibes better than weld.

[Edited on 12/12/06 by Wadders]

I'd drill right through like you suggest....failing that find someone with a bigger welder (Stick perhaps??) Oli.

Suggest, if you haven't already done so, that you check the neg and pos leads coming off the welder as these can fray and reduce power. Also mine improved 100% by using a meaty power lead from the wall socket (actually came from an industrial vacuum cleaner) - there must have been significant voltage drop using a thinner lead. Cheers, Pewe

Also bear in mind that the Clarke claims are well OTT as well.

My 150TE mig was supposed to be good for 6mm if my memory serves me right, I wouldn't use it on anything over 4mm, was at its limit on that.

Chamfer deep welds and build up on multiple passes. I welded a hydraulic JBC digger back cylinder coupling which was approx 2 1/2 inches in diameter with a standard car mig welder simply by having a huge chamfer and going round and round and round till I'd built it all up (used a whole real of wire). The weld has lasted 3 years of abuse and still going strong. The reason your weld failed is that it has cooled down to quickly due to all the cold metal around it and this has made it brittle, so preheat the job first. I make a habit of cleaning first with a blowtorch and wire brush before hand, which takes the chill out the metal. You’ll always notice on non preheated jobs that small tackwelds are brittle and that a weld onto cold metal improves as you work along due to the surrounding metal heating up. So get yourself a good blowtorch…

I'll try heating it (may even get the IR thermometer out to see how hot it gets ut doubt it will be much more than 200 C)

oh yeah reading exactly what your doing it sounds like the hole is to small, the arc from the welder is jumping onto the walls of the hole rather than striking the metal at the back. Try a 10mm,or larger hole and keep the wire in the centre till that areas molten then move out in a spiral till the pools flush with the top. Obviously it’s a tad tricky to do that on a small hole so make life easy on yourself.

My Clarke 130EN welds beautifully, even on 8mm steel, with great penetration...the trick seems to be to turn down the wire speed a little, and weld slowly, letting the heat get deep down into the work. I welded some hard 3/8" plate steel this way, and the back side of the plate was purple once cooled...LOTS of penetration. I went slow, and used a pattern of small, overlapping circles. Ended up looking like a rather smart TIG weld!
If you weld too fast (particularly with lower-power welders), you don't get much penetration, IMHO. Hope this helps...

re: zetec7hmmm, interesting; I have my wire wound up almost to max; I reckon if I slow it down, all that will happen is that is will melt itself inside the copper nozzle.:

(amp setting is on max BTW)

quote:

---

Originally posted by 02GF74
re: zetec7hmmm, interesting; I have my wire wound up almost to max; I reckon if I slow it down, all that will happen is that is will melt itself inside the copper nozzle.:

(amp setting is on max BTW)

---

My welding has improved so much since I replaced the rubbish earth sprung clip with pair of cheap mole grips with an M8 bolt welded to it and the earth cable bolted onto that.

Really has made a difference.

Regards

Rich