Bridging gaps

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When welding 18g whats the best way to fill or bridge gaps. 1/16 gap is about max.


Reply:Better prep makes for a better weld. Looks like the area on the right is perforated rust, and the top part still has some paint. You can use an aluminum or copper backing plate, and spot/stitch it together. Gob it on and grind it back, not the best method. You can also tack on some sheet metal slivers in those areas where the gap appears to be about a 1/4" or more. You could also weld some sheet metal on behind the repair patch to act as a permanent backer, if it not visible later when completed(like bottom floor pan of vehicle). Is this an old pick up truck ? What welder/wire are you using?HTHAirco 250 ac/dc Heliwelder Square waveMiller Synchrowave 180 sdMiller Econo Twin HFLincoln 210 MPDayton 225 ac/dcVictor torchesSnap-On YA-212Lotos Cut60DPrimeweld 225 ac/dcPrimeweld mig180Miller AEAD-200
Reply:Fit it tight and or overlap for stuff like that.www.urkafarms.com
Reply:I could be wrong but the only way you have any chance of welding that kind of gap is a back strap behind it. Otherwise its just going to blow apart with nothing to grab onto it, especially the top half where its seeing vertical heat.You'll need to improve fitup or overlap them otherwise.For parts like that, its a good move to hold carboard behind it. Trace it and transfer it to your piece. Obviously not always possible to fit the cardboard but when you can its a huge help.www.FirehouseFabricators.comZachLincoln 210mpLincoln SW200Hypertherm Powermax 45xp2x4 CNC Plasma Table.
Reply:Tig filler placed in the wider gaps.
Reply:

Originally Posted by M J D

Tig filler placed in the wider gaps.
Reply:

Originally Posted by albrightree

Old/damaged welding rods, knock off any remaining flux coating and cut to length. You could even bend them so you can hold them in place while tacking them in. Sort of MIG/TIG/Stick fusion.  https://www.weldingweb.com/images/smilies/biggrin.gif
Reply:Just weld down the edges until you can bring it all together. Welded some really wide gaps before. You can make metal where there wasn't. Just like filling in a hole. Having clean metal of sufficient thickness on both sides makes it easier though.
Reply:If your going to be doing a lot of it go to LWS get some assortment of oxy acet rod and some car body wire stitch it together takes a lot of time
Reply:I say work on fitting for the job.  I have made it a long time without those clamps.  This is a bit of case where learning too much too fast has drawbacks. Can see this type of joint in lots of vids and it has its place but here lap that junk, screw it down to hold if needed and noodle a weld on. This kind of fit is a waste for this type of job.  2nd,, when i am joining scrap for structural, say floorboard repair, that type of thing often use 16 ga.  Lots easier to weld and holds its shape.   There was a decent vid a while back about making a tack over with grinder cut patch that works and quite simple.  But i really rarely but weld and before anyone gets their panties in a wad its a semi lap which gets absorbed by the weld similar to back up ring or similar as putting a wire between these gaps would.  Maybe even better than hundred little zit welds would be on the back and as a side benifit leaves it slight low on the patch for a little filler.  Lots of body guys like to think they know how to weld but i make a patch a while back for old timer and he came back and said,,, that was the easiest patch i have ever finished.www.urkafarms.com
Reply:

Originally Posted by M J D

I won't do that with mig, the leftover flux that doesn't come off can add porosity to the weld.
Reply:Overlaps are your friend, pop holes in it to weld through - looks like factory spot welds sort of.All rust needs to be cut out to solid metal before fitting.Check out my one and only floor job for ideas

https://weldingweb.com/vbb/threads/7...irs?highlight=Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:

Originally Posted by albrightree

Old/damaged welding rods, knock off any remaining flux coating and cut to length. You could even bend them so you can hold them in place while tacking them in. Sort of MIG/TIG/Stick fusion.  https://www.weldingweb.com/images/smilies/biggrin.gif
Reply:Quote Originally Posted by johnfin View PostIts really a tricky proposition. This is not a 57 chevy where you can buy every part. This is a rusty jap car, plenum not available. In a perfect world i would replace the whole plenum but......the pinch weld is perfect and its acting like a tie beam. So i was thinking of putting the complete donor plenum over the existing plenum. Sounds dumb but i think it could work and be strong.
Reply:You could do those welds fairly easy by either "trigger welding" with the mig gun or "cajun tig welding" where you add a filler rod, like you would do tig welding, while you are mig welding it.If you trigger weld it, you are making little tack bridges. Keep putting them closer together until you have them about a quarter inch apart. Then start welding it from one end, stealing metal from the little bridges you put in. You will have to figure out how far you can go with out burning through, pulling and releasing the trigger as you go.