Blowing away at edges

[thepurpleblob]

I've got one of those Cerbora 130 amp jobs and I converted it to a Eurotorch which has made quite a difference to my welding. I'm doing car repairs so I'm only interested in thin metal welding.

On a .9mm plate and on butt joints with little or no gap, I'm getting great results. Really happy.

However, there's a few complicated bits I need to weld on the car and I've got some gaps (couple of mm tops). I have read about just building the weld up along the edges. However, I can't do it. Even trying on scrap metal as soon as I get near the edge it's just gone. I've got the welder on minimum and I've tried various wire speeds to no avail.

Any tips much appreciated - getting quite frustrated.

 

[tflnemesis]

If you can get behind the welds a heatsink would solve your problem, some flattened copper pipe or solid copper block. The only thing i have found for bridging gaps above 1mm is laying wire across the gap, by advancing wire from tip lay it down and just blip the trigger but, this makes for messy welds and i only ever do it if i can't get in with heatsink or gap is too narrow for me to drop a filler piece in.

 

[thepurpleblob]

Ok - I can definitely get in. Where might I get a solid copper block? I tried it with a bit of flattened 20mm copper water pipe when welding up some holes I blew earlier and it didn't seem terribly effective. Not enough mass I suspect

 

[the snooper]

if you can get into it cut a bigger gap and put in a new piece of steel it will be much quicker and neater in the long run

 

[thepurpleblob]

I know but it's a compound curve. I'm letting in a bit cut from a scrap car and I've not cut it perfectly. I don't fancy my chances making up a bit to plug the gap. Plus it's in a tricky corner.

 

[the snooper]

other easy way is to put a thin strip behind it then weld it

 

[thepurpleblob]

Good idea... it doesn't need to look pretty. It'll be completely hidden away when everything's back together. I would prefer if it was all delightful but let's not get carried away

 

[the snooper]

just make sure you paint / seal the back or it will rust inside out

 

[steveo3002]

usualy find offcuts of copper or brass on ebay , i use a couple of bits of brass that fit most situations

 

[brightspark]

copper or ally are the best for heat disipation

 

[thepurpleblob]

Cool - I'm a rubbish welder but I'm an expert with seam sealer

 

[norlander]

Also try pulse or stop n start again quickly on gaps-like a joined up series of spot welds-this usually works for me you can then clean up and build up the weld with a straight run, gasless MIG is good for this as their is no slag-just the gas deposits to clean up.

 

[Sean]

Try not to finish welding on an edge, as the heat has no where to go you end up with a horse shoe hole stop about an inch away , let it cool and complete the last inch starting at the edge and running in to your last stop when the weld is good and hot.
+ 1 for the copper chill bars make a selection of differing shapes by batting some pipe offcuts flat and bending to shape.

 

[brianblock]

Have you tried using a big weave?
Start at the far corner back along one side of the gap across the end of the weld (may have to pause slightly) then back out to the far corner of gap.
weave will probably have to be pretty quick to keep the heat moving.
Ive managed to fill holes upto about 10mm across using that method. just remember to stop often to let the surrounding area cool right down.

 

[Wallace]

With a copper/brass backing plate the molten steel usually sits on it helping to bridge gaps. Using compressed air to cool in between tacks also helps to keep the heat down so you can build up edges and prevent distortion.

I used a brass plate to add this small section of 1.5mm on an outrigger panel to avoid using a larger sheet and wasting material. When clamped down the penetrating weld pool sits on the brass leaving very little to sand back.

 

[marlinspike]

What settings are you using at the moment? I have a Cebora and struggle not to blow through too. The thin metal technique helps, so does a copper sink bar - you can find them on ebay as mentioned. Using a wet/damp towel to cool the weld helps, if you don't have access to compressed air, or if you can't get a copper bit behind the weld.

I find it massively frustrating that one minute you are going great, then the next you have blown through.

 

[Roadrally]

I've got one of those Cerbora 130 amp jobs and I converted it to a Eurotorch which has made quite a difference to my welding. I'm doing car repairs so I'm only interested in thin metal welding.

On a .9mm plate and on butt joints with little or no gap, I'm getting great results. Really happy.

However, there's a few complicated bits I need to weld on the car and I've got some gaps (couple of mm tops). I have read about just building the weld up along the edges. However, I can't do it. Even trying on scrap metal as soon as I get near the edge it's just gone. I've got the welder on minimum and I've tried various wire speeds to no avail.

Any tips much appreciated - getting quite frustrated.

What wire are you using?
If you're on 0.8 you could change to 0.6 which will reduce you're amps.
Other than that the pulse method is good as someone else mentioned.

 

[marlinspike]

0.6, having changed down from 0.8 after reading the same advice
on here. I do need to sort out a decent bit of copper as a heatsink though. The bit we use is pretty thin and I'm not sure it is doing it's job. I have been using the pulse techniques but don't seem to get the neat welds I see on the forum and struggle not to blow through.