I have some small blow-through holes - best action?

[markyboy944]

Hi Lads

I've eventually built up the nerve to weld a replacement Sill section on the car, and it actually didn't go TOO bad.

Seems strong , has penetrated nicely.

DOWN side is, I have some blow through holes.

These are pretty small, (say 4mm x 4mm for biggest).

My question is, whats the best technique for these ?

I have read about a technique somewhere where you put something behind the hole, but I must admit , not sure how I'd get this to work in a small hole of 4x4mm

Another (wicked) thought was just to apply filler ?

(My worry is, when I was on the welding course, I had blow through, and whatever I tried it ALWAYS got WAY worse).

any help - MUCHO appreciated - Thanks

Mark

 

[oddball90]

Run weld around the edge of the hole, slowly building up till you seal the hole. But don't try to fill in one go, start and stop to let it cool down. Case of just trying it, would have a go on a scrap peice first though.

 

[markyboy944]

OK - (How do I make sure the weld goes through?)

Hi - thanks for that mate.

The actual holes are pointing towards the floor slightly (so in a way gravity working against me).

Just wondered , if I build up around the hole, how do I make sure the weld goes right through, so when I grind back, I don't end up with a hole again.

(Is it a case of, when there is some build up, put the wire "in" and ensure some weld builds up around the back ?

Another way of putting it is, how do I not end up with a kind of volcano of weld, i.e. it build up and up , but when ground off, the hle is revealed.

Cheers - Mark

 

[kezajones]

Run weld around the edge of the hole, slowly building up till you seal the hole. But don't try to fill in one go, start and stop to let it cool down. Case of just trying it, would have a go on a scrap peice first though.

+1, i do that, normally on a slighty lower power setting,

 

[kezajones]

Hi - thanks for that mate.

The actual holes are pointing towards the floor slightly (so in a way gravity working against me).

Just wondered , if I build up around the hole, how do I make sure the weld goes right through, so when I grind back, I don't end up with a hole again.

(Is it a case of, when there is some build up, put the wire "in" and ensure some weld builds up around the back ?

Another way of putting it is, how do I not end up with a kind of volcano of weld, i.e. it build up and up , but when ground off, the hle is revealed.

Cheers - Mark

i normally do the first layer "in" the hole, like at the bottom on the side and work up

 

[oddball90]

Run the weld around the inside of the hole, only the last run goes over the top.

 

[peterd51]

Hi,

turn the mig to it's lowest, on my Clarke it's 1 min, and then pulse the trigger on and off burning for about a second each time.

Go all around the outside rim of the hole until you've got a complete weld. If any part of the weld glows red hot then pause a few seconds to let it cool...this stops your new weld from burning through.

Once you've got some weld to attach to (rather than the much thinner plate) then you could run continuous weld around the hole in a spiral gradually placing new weld on top of existing weld.

Try to keep it on one level rather than like a walnut whip...

and if it starts to glow stop welding for a few seconds until it cools.

When you get to the middle of the hole, let it burn for a second or so and it'll start to sink and pull the middle down. The trick is to stop just before it blows through again.

Drill some holes in some scrap to practice on.

Regards
Peter

 

[TechnicAl]

just jam a piece of wire in the hole and the weld over it. If its 4mm, use a bit of a 4mm stick rod. As long as its mild steel it doesnt matter what it is (a nail or screw will do) then grind off the excess.

 

[matt1978]

just jam a piece of wire in the hole and the weld over it. If its 4mm, use a bit of a 4mm stick rod. As long as its mild steel it doesnt matter what it is (a nail or screw will do) then grind off the excess.

Technical AL's dodgy car lot!!

 

[TechnicAl]

its only a sill and you were going to use filler !!!!

and if your straight welds have holes wait till you try the walnut whirl technique (get some 6" nails ready)

good luck

 

[aametalmaster]

Back it up with a small piece of copper than weld over the hole. Smash some copper pipe flat if you can't find piece of bar stock...Bob

 

[Rusty]

Technical AL's dodgy car lot!!

Make sure you grind them nails off or it'l make a right mess of yer takeaway with them poking up through yer carpet