Mig brazing body panels

[pdrpaul666]

Hi there I'm looking for some advice. Have some welding to do on my rear quarter which I'm obviously going to have to grind flush for a clean repair. Iv been using a 151te Mig welder with 0.6 regular wire and c02 for gas, my problem seems to come when grinding the welds flush as the weld is very hard by the time I grind it flush I'm taking a lot of good metal either side with it then before I know it I'm left with wafer thin steel, I'd like to try running brazing wire, as its galvanized steel my thoughts are lower temperature weld will help with warpage etc and mainly due to the fact it will be a slightly softer metal to grind down meaning IL grind the weld flush without touching the steel either side. I also like the idea of using a backing strip / sleeve to help during welding process. I know this cold cause moisture trap but I will be sealing the rear anyway. I been using grinder to take welds down with 60grit flappy disc, but really like the look of the narrow belt sanders to get some precision. Any help would be much appreciated thanks.

 

[Dragnet]

I have limited experience of this, but have not had the trouble you describe. I do the butt welding, then work along the joint with an angle grinder and grinding disc, working backwards so the part that's been ground is visible in front of the grinder. I take that down until it's near but not touching the metal either side. Then a flap disc can take down the rest more gently, followed by a sanding disc on a rubber backer or a double-action disc sander tool. With this method I've not found myself taking away much parent metal.

I have bought a thick copper bar from Macc Models which I clamp on the back of problematic sections or where a gap needs filling, so it draws away the heat and makes a flattish rear to the weld. I have made some thinner, longer pieces from copper plumbing pipe squashed in a vice which is easier for curves as it's more flexible.

I have no experience of brazing wire. If it's galvanised, have you tried removing the galvanising from the joint? I'm sure someone more experienced will correct me, but I believe it could cause some problems.

 

[JOEPRO]

I do alot of car bodywork welding and do not have any issues thinning the metal.

Just be precise and careful when dressing the welds back with a flap disc. Fresh flap discs tend to cut faster so I buy em bulk on ebay.

 

[Onthespotwelding]

Fresh flap discs tend to cut faster so I buy em bulk on ebay.

Which ones do you buy as I’m running low myself

 

[JOEPRO]

Which ones do you buy as I’m running low myself

I buy 60 grit from here

Pardon our interruption...

I also buy the mini me 60 grit roloc flap wheels

 

[superclarkey]

I personally only ever use 0.8mm wire on bodywork.

I would try a CuSi3 wire, but be aware you need to run DCEP, run 100% Argon, run a teflon liner and use U rollers in your mig. Its also recommended to use high frequency pulse which really helps the process along.

Don't use CuAl8 wire if your going to acid dip the car after repairs

As for abrasives I use 3M Rolocs mainly or 3m Cubitron II flat discs in a grinder a its the fastest way to bring welds flush.. A 3m Cubitron II belt on my belt sander is a great way too.

 

[Keithmac]

I buy 60 grit from here

Pardon our interruption...

I also buy the mini me 60 grit roloc flap wheels

View attachment 389783

I have that exact same set up, works a treat. Bought a bag of #40 Roloc disks for knocking welds down.

The M12 is nice and light, nice to use for long stints.

 

[Myles1970]

I sometimes take the tops off the welds with the edge of a grinding disc, and finish off with the powerfile. Obviously taking care not to work the same spot for too long to allow the heat to dissipate.
I try to stay away from the flappy discs as I tend to get carried away with them . Also, I'd rather have to knock a high spot back and fill than risk wafer thin metal

 

[Brad93]

@HughF is an expert on mig brazing auto panels

 

[HughF]

I’ve run rolls of the stuff…. Through both a normal transformer mig (the old sip ideal range being particularly well suited) and my kempii minarcmig evo200.

Standard rollers, standard liner, argon gas.

I wouldn’t use anything else for bodywork, it Really is superior.

 

[HughF]

And as for grinding welds down, I always use the edge of an old school 3mm thick grinding disk. Working at 45 degrees to the weld seam. I then finish off with a miniature 60grit roloc pad on a modified 12v cutoff tool.

 

[Justme]

I been using grinder to take welds down with 60grit flappy disc,

Thats your problem. Flap disks can curve and cut both sides. Use a hard disk.

 

[Justme]

I’ve run rolls of the stuff…. Through both a normal transformer mig (the old sip ideal range being particularly well suited) and my kempii minarcmig evo200.

Standard rollers, standard liner, argon gas.

I wouldn’t use anything else for bodywork, it Really is superior.

Is it a steep learning curve?

 

[HughF]

Is it a steep learning curve?

Not at all…. Pull trigger, brazing happens

 

[AVI_8]

Does it have to be 100% Argon or would 93% hobbyweld5 work ok?

 

[HughF]

Does it have to be 100% Argon or would 93% hobbyweld5 work ok?

93/5/2 works fine too, just a little more sooty

 

[zeppelin builder]

I do alot of car bodywork welding and do not have any issues thinning the metal.

Just be precise and careful when dressing the welds back with a flap disc. Fresh flap discs tend to cut faster so I buy em bulk on ebay.

View attachment 389768View attachment 389769View attachment 389770

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[/QUOTE
dont worry its nothing a 9 inch makita cant fix

 

[pdrpaul666]

Awesome replys guys.. so running a brazing wire is fine on standard rollers etc only difference is the gas n wire and I'd assume lower power setting, I also never really thought of flappy discs flexing n taking the good metal either side down with it I will give using a 3mm grinding disc a go. Would love to get a roloc tool so I can use smaller discs etc is their any recommendations on a good electric one or are the majority air tools, as for power file I remember hearing black and Decker do a good one and to use zirconia belts I think if memory serves. Any recomendations?

 

[Shox Dr]

Awesome replys guys.. so running a brazing wire is fine on standard rollers etc only difference is the gas n wire and I'd assume lower power setting, I also never really thought of flappy discs flexing n taking the good metal either side down with it I will give using a 3mm grinding disc a go. Would love to get a roloc tool so I can use smaller discs etc is their any recommendations on a good electric one or are the majority air tools, as for power file I remember hearing black and Decker do a good one and to use zirconia belts I think if memory serves. Any recomendations?

I stuck a 50mm Rocloc on the end of a Parkside 75mm cutoff tool. Works a treat, bigger battery lasts a long time. The key to using one is to let the disc do the cutting. Helps with panel distrotion and thinning as well.

 

[pdrpaul666]

I stuck a 50mm Rocloc on the end of a Parkside 75mm cutoff tool. Works a treat, bigger battery lasts a long time. The key to using one is to let the disc do the cutting. Helps with panel distrotion and thinning as well.
View attachment 390390

Off to check lids site now lol.. looks ideal