Welding thin plate ...

[ChrisF]

A question for FROLL and the other guru's


A friend is busy overhaulin a 80's Landy.

Yes, the firewall has some bad rust. A few areas must be cut out, and new plate welded in. The one "side", where the door bolts onto, has to be replaced as well.


The local Landy shops want more than R7k for refurbed firewall !!


My friend has an inverter welder. Thus a 2mm rod and low amps is about as good as his toolkit gets .... with limited experience, but he already got some thin steel to practice on.


Is this even possible ???

Is he lining himself up for a big headache ???

What are the options - with this equipment ???



all searches points to going mig/tig .... but this is obviously not an option for a one time project.


Would appreciate any and all practical advice.

[Rigger]

For an inexperience welder i would not concider it. Arc welding is very difficult on thin plate. Best would be to tack, cool down, tack, cool down etc. Don't try to weld a complete run as the heat will get too much. Most probably going to end up with lots of holes burnt through if you try to weld a long piece at once. Why not try brazing it or even silver solder?

[pietpetoors]

No it is too thin. A Tig welder or gas will do the job.

[The Legend]

No it is too thin. A Tig welder or gas will do the job.

[ChrisF]

I do have an oxy-acytelene set. So this may be the better route to go then.

What type of gas welding :
- metal filler rod ?
- brazing ?
- I know back in the day they used to solder the joints. not even sure if one can still get the materials for this ....


how do you manage the heat and not warp the firewall ? Lots of shorter welds with cooling in between, or can one just weld along .... Or should we make up a jig to bolt it down properly to prevent any warping ?


The gent is only 26 years old, and really making an effort to properly redo the Landy, while trying his best to do everything himself .. both to keep the budget in check, and mostly because he had his heart set on a "project vehicle" and takes pride in his project. The type of youngster one really wants to help.

[Thabogrobler]

Some may shoot me but what about some good 'ol fibreglass?

Cover the whole firewall and sort the tin worm forever(or at least a few years?)

[ChrisF]

Some may shoot me but what about some good 'ol fibreglass?

Cover the whole firewall and sort the tin worm forever(or at least a few years?)

Should work for 80% of this project - in terms of "blocking the holes".

But there are two bits visible from outside the vehicle, including the A-pillar section where the doors bolt on. So some metal work is required ....


Jaco has actually done a pretty decent job thus far fixing stuff which many would have dusted and painted over .... he is not keen on cutting corners.


he is even looking into laser cutting to replace some hard to find parts. Any tips on the process - CAD drawing and what line offsets are required etc would be welcomed.


Started off with me giving some advice on minor items .. now I am learning as the project goes further.

[Froll]

No it is too thin. A Tig welder or gas will do the job.

I have welded thin plate with 2mm rods by clamping a piece of copper flat bar behind the weld. also just tack at spacers and slowly get a full weld. You do end up with some warping and does not look good as grinding smooth is also difficult. Gas welding will be better, use a wet cloth to cool a run of about 20mm welds. Does still warp a bit but can be pannel beated a bit. Brazing I have found at times that paint does not stick very lekker. ( Very early attempts by myself.) Fiber glass will also work quite well. If a mold can be made of the whole pannel, also works out expensive and if you dont have good knowledge of it you could end up having to break the part out of the mold and damage it.
I would personaly go with firstly TIG then MIG then gas welding. Even MIG welding thin plate is not so easy, I know as I have just done my truck.
Is it not maybe possible to hire a TIG welder somewhere?

[pietpetoors]

I have welded thin plate with 2mm rods by clamping a piece of copper flat bar behind the weld

If you do not have copper flatbar you can also hit flat a piece of copper pipe so that it looks like flat bar, works just as good.

If your friend has the time and money let him go do Barry Ashmole's sheet metal forming course. It is worth every cent especially if you are interested in restoring. I did it two or three weeks ago.
See:
https://www.facebook.com/The-Garage-Cla ... 857822743/" onclick="window.open(this.href);return false;

[ChrisF]

BAIE DANKIE !

Roger the copper trick sounds neat ... I will speak to my neighbour, he is an electrical contractor. Sure he has copper buz-bars ..... For this project, this may well be the silver bullet !!


Pieter baie dankie vir daai link. Ons sal beslis weer kyk hierna .... die projek gee my mos nou juis planne om oor so paar jaar met Maritz (ons peetkind) n projek kar aan te pak .... dalk moet ek so bietjie oefen met "body-werk" ....

[ChrisF]

No it is too thin. A Tig welder or gas will do the job.

I have welded thin plate with 2mm rods by clamping a piece of copper flat bar behind the weld. also just tack at spacers and slowly get a full weld. You do end up with some warping and does not look good as grinding smooth is also difficult. Gas welding will be better, use a wet cloth to cool a run of about 20mm welds. Does still warp a bit but can be pannel beated a bit. Brazing I have found at times that paint does not stick very lekker. ( Very early attempts by myself.) Fiber glass will also work quite well. If a mold can be made of the whole pannel, also works out expensive and if you dont have good knowledge of it you could end up having to break the part out of the mold and damage it.
I would personaly go with firstly TIG then MIG then gas welding. Even MIG welding thin plate is not so easy, I know as I have just done my truck.
Is it not maybe possible to hire a TIG welder somewhere?

Saw a nice youtube video where the guy shows the follow :

- spot weld the plate at about 30 to 40mm intervals, just to get it in place
- now stitch weld one of these sections (even with the TIG he was stich welding to keep the heat down, with the inverter this would probably be a long process of many many tack welds)
- then SKIP two or three of these "sections", and stich weld another section of the panel .. to move the heat away from the first section
- keep on skipping to totally different sections ....

PS - but all these videos use mig or tig .... which we dont have ...

[Mud Dog]

I've arc welded some tin material before but here I've got to say that it was lying flat and I used wet sand as a heat sink. Welding vertical body panels in place is another matter altogether.

This I have done with brazing on the odd occasion before we had inverters and TIG welders, and even then it wasn't continuous welds but a series of tacks about 40 50 mm apart. These were done very wide apart to secure the piece in place and then the closer ones were 'filled in' by 'hopping' from one area to another so as not to create too much heat in one specific area. As Roger said, you do still get some deformity of the metal, but it's normally not too bad that it cannot be beaten flat.

Good luck with the project.

[Dowe Koos]

Hallo Chris. Gassweis is die beste opsie vir wat jy wil doen. Spotsweis eers alles aanmekaar en dan sweis jy. Belangerik is dat die bottels se druk reg is. Daar is basies drie vlam verstelling wat mens kan hê.

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Verstel jou vlam soos met die eerste prentjie..
Volgende een sê vir jou watter grootte nozzle vir watter dikte plaat en ook wat die druk in jou bottels moet wees.

Volgende een sê hoe dit voorberei moet word.

Laaste een sê hoe lank dit moet vat om sekere afstand te sweis.

Jy moet maar redelik vinnig werk, maw moenie te lank op een plek bly nie anders word die plaat te warm en dis waar die probleem begin. Voorstel - oefen maar eers op paar stukke plate tot jy voel jy kan dit doen.
Hoop dit help.

[ChrisF]

Dankie manne.

Andy at least the Landy's fire wall has been taken out of the vehicle. So we may still play with the wet sand trick ... Copper buz-bar AND wet sand ?? ....

[Mud Dog]

I would still go for TIG, but if you can't swing that, then use the copper heat sink (aluminium will also work). Test your inverter on some thin plate with 1.5mm rods and the amps turned down as low as you can manage - if it's a decent inverter you should be able to tack with an amperage as low as about 50A. The thinner rod will burn hotter than the 2mm but with the lower amps you should be able to bring it down to a similar arc heat, the overall heat will however be a lot less and will lessen the chances of a burn-through (also less deformity).

If you use the wet sand trick, bed the work-piece down nicely so that there is ample contact area (underneath) - then on top you can also lay some lines of wet sand on either side of the weld seam ... not too close, about 30mm away and ensure that there are no sand grains to contaminate the weld (it will turn to a crude form of glass with the heat).

[Stef]

Maybe you could try these guys:
http://www.independent4x4.co.za/contact_us_5.html

R7k sounds expensive, but considering the time that goes into it it's actually not that ridiculous, and you could take it back if something goes wrong

I'd try to borrow a proper spot welder, or get that glue they use to assemble cars these days

[ChrisF]

Thanks guys.

Stef I am sure the R7k is not unrealistic .... but Jaco bought a "prject vehicle" as he WANTS a project .... obviously some parts of such a project pushes your skill level more than others .... But he wants to learn !

Pieter's suggestion of those classes sounds like a worthwhile detour for this project ... a detour I may well join .... thinking ahead I would LOVE such a project with Maritz in a few years ....