have a front door cast iron door mat thats broken, would it be possible to mig weld it?
With normal mild steel wire it will probably crack straight away. Lots of methods to join it successfully but mild steel mig isn’t one.
Perhaps I should of been more specific.
Yes you can weld cast iron with mild steel wire if your simply sticking it together for decorative purposes. High risk of it cracking mind straight after due to contraction.
If you want a join equally as strong with no contraction issues you may as well just use super glue.
I seem to remember reading that if you add bicarb to it it strengthens it?
Nothing wrong with pound land super glue
I always find the caps weld themselves on after the 3rd or 4th use so I refuse to buy £3 tubes when I can get 6 for a quid.
Have done it once before on an cast engine.
Got it glowing with an oxy torch, welded it with a mig, and then gradually let cool with taking the heat off with the torch.
Worked to an extent.
It was a secure weld, (held the engine to the mount alright) but wasn't water tight where it had cracked into a water gallery.
If it''s on something decorative/non load bearing go for it,
I buy these over other brands of mitre glue/superglue (not from screwfix too expensive) because the lid and spout are both threaded. Easy to get grips on both pieces and open them once they've bonded.
with the risks of it cracking, not being strong enough and my newbie welding skills id probably be better with the super glue
ill report back later, thanks for the help
Any powder will do really. I have used talc before and sawdust.
On a similar note, I'm trying to repair a trailer jockey wheel clamp by welding a nut over the bolt hole to provide a thread for the bolt. The body of the coupling is cast while the nut is mild steel. Had a go last night and as soon as I tightened the bolt it popped off. Looking at the weld I barely achieved any penetration at all, so I'll try turning the power up next time, but should I preheat the casting or anything else first?
If I understood this correctly your trying to join a steel nut to cast iron?
If that’s the case your only real hope is a brazed joint.
Ok, will do some reaearch on that, thank you. I might just have to give up on the whole idea and buy a jockey wheel to bolt on to the a frame but I have hope.
I’ve repaired cast iron sewing machine legs using unknown brazing rods and oxy propane for heat
Clean, degrease, v prep, clamp and go for it. Dressed up afterwards. with a lick of paint the joints are invisible, still going strong after two years
Just had a thought, is my coupling on the trailer more likely to be cast steel rather than iron for the strength?
Find an unimportant area and give it a dab with a flap disc on grinder.
Take note of the sparks colour.
If it’s iron they will be less visible and a deeper orange colour. If it’s steel a bright yellow and more of them.
My guess as that nut just pulled straight off with a little nip up it’s cast iron.
Unless you really did an awful job of welding it on it should of withstood a bit more force on cast steel.
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