mig welding a long thin panel

[Monkey Harris]

hi guys ,

im restoring a vw camper ... and have welded quite a few different parts.
i will soon be looking to weld a 3 ft long side panel,
how would you do it ?

i seen a few articles from the US
saying that mig is not good for butt welds on thin panels these are 0.9mm

ive seen a few panels warped by to much heat,

im tempted to butt weld it with a steel strip behind it to absorb the heat and stop the edges burning,
the back has a ply lining and units over it

a lapped joint may work but i suspect will flex and crack the filler

how about joggling and plug welding ..
anyone done similar to this panel ..?


it fits from the bottom of the cut panel onto the inner sills in black

 

[gaz_moose]

weld it a bit at a time, to keep the heat out.

 

[Shedendman]

Butt weld it with a slight gap,your wire size will do 0.8?
First or all you need to clean that edge(suck eggs etc) try not to thin it to much though
Got any small strong magnets? Ones from old hard drive are ideal
Offer your new repair peice up place magnets so its along the gap edge so new and old are all flush,take your time on setup as this is most important
Now the cooling backing bit should be copper bit of 15mm tube sliced and flattened out will do,how you get it to stay on the back is your choice.
once you're all setup up and everything's inline and flush check it again
Now time to tack it space these out say just off each corners the say every few inches apart,take your time here what we dont want is to much heat put in otherwise it'll distort once your happy remove the mags then its a case of stitch welding say about an inch at a time or 5-6 bursts like this
http://www.mig-welding.co.uk/thin-metal.htm
I split the the weld area like a clock,start at say 12 then do a bit at 4 do a bit then at 8 so on so forth work your way around the repair,dont rush,allow to cool
Practice on thin scrap till you think you've got it sussed

 

[Burdekin]

Also cool the weld straight away with compressed air of a damp cloth. Move to different positions on the panel and weld small sections. Check the panel often as you go.

Can you access the back of the panel once you have the repair section in place? If you can you can planish the welds a bit if required to remove the stress in the weld.

If it was my car I would tig or gas weld the panel and planish the welds as I go, that is if you can access the rear otherwise mig is your best option.

 

[AndersK]

I would like to add one thing, watch the gap after EACH tack. When you see it shrink, hammer & dolly until the gap is uniform again. It takes time but trust me, it's worth it at the end if you're not used to do body work.

 

[mike 109444]

With a (flexible) steel rule you can check that the curve of the panel is following the curve of the original metal. If you hold/press at the points marked "x" then the rule should follow the curve.
Use inter grips to hold panel in place.
Avoid pushing the panel or original metal to "make them line up cos when you weld and release it will want to return. Bend, fold, tweek the new panel untill you can "place" it on and it meets the original edge.
TRY to get to rear and do some of the welds from that side.
Note at the joint the weld will "sink" so take care when grinding down. Try a belt sander (fine belt) and lightly let it follow the curve.

 

[mike 109444]

Sure someone was showing an ad for a tool to just form a slight lip on each edge of a butt weld panel to give a bit more metal/stiffness at the weld edge.
It would form like the pic below.

 

[Shedendman]

@monky harris
All good tips given there,the one main thing is practice practice and ditto etc blah blah blah
Take your time

 

[Monkey Harris]

@monky harris
All good tips given there,the one main thing is practice practice and ditto etc blah blah blah
Take your time

Yep lots of good tips...

Would anyone joggle the new panel,the weld the edge of the old panel into it, so a sort of lap weld..
Just pondering..

 

[Shedendman]

Personally no i wouldn't,dont be scared,practice butt joints with a root gap
You do it like that you'll still have a rubbish line and lots of filler to use

 

[Burdekin]

Yep lots of good tips...

Would anyone joggle the new panel,the weld the edge of the old panel into it, so a sort of lap weld..
Just pondering..

I would just butt weld. Mig is all about minimising heat into the panel.

 

[Monkey Harris]

Personally no i wouldn't,dont be scared,practice butt joints with a root gap
You do it like that you'll still have a rubbish line and lots of filler to use

Yup ..forgot about the size of the edges..

 

[Monkey Harris]

I would just butt weld. Mig is all about minimising heat into the panel.

True will practice with a damp cloth to cool..

 

[steveo3002]

try not to take too much notice of americans , often see massive bodges and bad workmanship

people on here will steer you right

 

[frank horton]

just to add,
rebuilt the body on a Citroen DS, the original rust bucket.....hahaha.....plus others.....it was a wagon so 5 doors to do......
I joggled mine and spot welded thru the hole made on the panel with the other side of the tool.....also used some long legged, deep footed vice grips to keep thing in place........had good accèss to the back tho.....alternated the welds along the edge , say every other 5 or 6 holes.......laid a big lump of brass plate down to get rid of some of the heat and used an air line for extra cooling....worked for me.....
used a decent brush on primer for the inside, then wax oiled.....the outside was body filled and painted by a pro.....
that was 4 years ago......still looks good, would get a photo for u but it's new owner lives in Amsterdam....

as it happens I have as my forever car a 99 VW, T4, 5 seater, all original paint and wax oiled from new....quite a few dent's tho but no rust other than stone chips....
just put electric leather seats and swivel bases to the fronts and gonna pick up 2 full leather skins in the same colour this week to get the rears to made to match... ....at my age won't need a surf board tho....hahaha.......def not lowered and original wheels.....
in the UK now but when I get back home will be replacing 3-4 gear synchro and do the overdrive conversion to 5th gear.....
then I'll be happy.......loads'a fun........
frank

 

[Wendelspanswick]

Remember for MOT purposes you can't spot or tack weld structural repair panels unless the original was spot welded.
By this I mean you can't cut a patch out of the centre of a sill and then tack weld or spot weld a repair plate in, it has to be a full seam welded. If the original sill was spot welded in place you can remove the whole panel and spot weld a replacement in.

 

[Burdekin]

True will practice with a damp cloth to cool..

If you can get a dolly behind and if you do get some warping just grind a flat on the weld, dolly behind the weld and hammer on the weld to stretch that area. Don't try and hammer the sheet, you will make it worse. Practice on a few wee panels, use a ruler to see how it moves and how it moves back when you cool it, then how it will straighten more if needed when planishing (hammering) the weld. I plannish as I go along but as I said previously if I can get access to the behind I would tig weld it, it's slow but when you plannish the weld it brings it all back straight. Mig is a hard weld so you need to make sure it doesn't crack when planishing but if you go slow and minimise heat it should be reasonable without plannishing. Also play with your panel gap, start off with a 1mm gap and see how that goes, but see what works best for you and your welder settings.

 

[Burdekin]

Couple of posts that might be of help.

http://www.mig-welding.co.uk/forum/threads/oxy-welding-flat-panels.65915/#post-855846

http://www.mig-welding.co.uk/forum/threads/replacing-rusty-bits.65628/page-4

 

[Monkey Harris]

So... the repair panel has arrived,

it is a cill [on the left] attatched to a panel,

it is designed with an option, to go up past my cut side,

to the strengthening bar inside,

the top of this part has a stepped edge to allow the existing side panel to be flush fitted ,

i have offered a scrap steel [orange] to see how it would go,

has anyone used similar .?

im assuming this folded top edge would help in heat dispersion and strengthen both edges,

 

[Shedendman]

Now that changes things a little,I'd be now inclined to plug weld along that edge,get yourself a punch
http://www.ebay.co.uk/itm/Joggler-P...627634&hash=item1c4d6534c6:g:BTMAAOSwm8VUy5mr
Thats a 5mm dont use a drill as you might put the orange panel out with drill pressure you could always open the holes bigger with a step drill say 8mm
Space your holes out neat and plug weld away,it would have been spot welded originally anyway.

Just had a though,this strengthening bar on the inside i take it the flange part of the new panel fits over the top?
Can you do a photo if poss of a dry fit?