Puddle welding

[ethel]

Having found some time to get back to working on the Stag that's been lurking in my garage (since 2002 according to the tax disc), last week I tried welding the centre top-hat section to the floor pan (the one that runs across the car just in front of the seat runners). Of course it should be spot welded in place, but as I have a Mig welder I tried making puddle welds, i.e. holes drilled in the floor pan above the tophat section flanges and then welded through the holes.

As you can guess if it had worked well I wouldn't be writing this. All I seemed to be able to do was fill up the hole and make a joint that came apart as soon as I threatened it with an old screwdriver. I based the size of the holes I drilled on the punch that is on my joddling (joggling?) tool (about 4 or 5 mm) and had the welding current set for 1.5mm material using .6mm wire. Can anyone who's done this successfully enlighten me where I'm going wrong? From what I've read it shouldn't really be necessary to make a large hole (say 10mm) and weld around the inside of that, though that is what I may have to resort to.



Many thanks, John.

[jamcarr2]

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try turning the wire speed down

john

[Cheesy]

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When I was teaching myself to weld, I found this website a great help. Here is a link to a plug weld tutorial:

http://www.mig-welding.co.uk/plug-weld.htm

[ethel]

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Thanks for the quick replies, the holes in that tutorial are certainly bigger than I've been trying andI think it makes sense to try as slow a speed as possible to give the bottom bit more time to melt before the hole gets filled up.



John.

[redstag]

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The punch on my joddler was too small as well. I think you can get abigger punch and die to fit but I just drilled bigger holes in the panels. 6 or 8mm I think.

Sounds like tou need to crank the power up a bit as well to get good penetration.

Pete

[Mark S]

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Cheesy wrote:

http://www.mig-welding.co.uk/plug-weld.htm

Great site - thanks.

Mark.

[alan_thomas]

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Another thing - was the material of the bottom plate ie not the plate with holes in really clean bare metal and earthed to the top plate?The arcwill happily bent and lay weld down on the fresh steel of the drilled hole and avoid the bottom plate unless both are very clean and earthed.

I plug welded the floor on my lotus 7 with about 200 welds, found a 1/4" drill the best size and became quite an expert but only did the actual job after practising on test plug welds on scrap of the same gauge. Plug welding is neat and as strong as spot welding if done well.

Last thing - I used weld thru primer on both surfaces before welding (after getting very clean steel)as uncoated steel is a magnet for the old rust!

- Alan

[ethel]

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alan_thomas wrote:

Last thing - I used weld thru primer on both surfaces before welding (after getting very clean steel)as uncoated steel is a magnet for the old rust!

Alan - did you completely cover the surface without the holes in weld thru primer, if so I assume this doesn't affect the arc? I think the earth was ok, I clamped the end flange of the outrigger to the sill bottom flange with the earth clamp.

Pete - I'm going to try something like 7 or 8 mm holes next time.

Thanks, John.

[alan_thomas]

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ethel wrote:

alan_thomas wrote:

Last thing - I used weld thru primer on both surfaces before welding (after getting very clean steel)as uncoated steel is a magnet for the old rust!

Alan - did you completely cover the surface without the holes in weld thru primer, if so I assume this doesn't affect the arc?

Thanks, John.

John, yes covered complete surface with weldthru primer. I found the best result were obtained holding the torch shroud vertical to the hole and aimed at the centre. The weld then builds from the bottom up. I made a sleeve that fitted over the shroud with 2 'legs' on it like this:-

http://www.justoffbase.co.uk/2-X-Mig...per-W578P?sc=9

it allows you to push down on the top plate getting good plate to plate contact at the same time allowing you to centre the torch over the hole. If your mig has a timer function (mine hasn't!) it is even better has you can set it to just fill the hole.



- Alan

[ethel]

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I got one of those shrouds, but it seemed to bring the tip too close to the work and I ended up with weld stuck to the tip and the wire. Maybe with a larger hole to weld through it might be better, or I could just make a small spacer to lengthen the shroud.



John.

[alan_thomas]

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Are you using clean wire? I found if the wire has been in a garage over winter it becomes lightly corroded / tarnished and does as you say, cause intermittent weld and sticking to the tip. Try winding out several feet of wire cleaning it with a 'scotchbrite' type pan cleaner then winding it back in. If the welding improves then its the wire. I always take the spool out of the welder and keep it in the house it its going to be weeks before using it again. - Alan

[ethel]

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I've got a new spool - still in its wrapper - probably worth trying that along with everything else, then if it still doesn't work I'll know it's an operator problem, rather than the tools

[ethel]

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Thanks to everyone who made a suggestion, tried it this afternoon with bigger holes (8mm), clean wire, slower wire speed and 'special' shroud set with the legs protruding beyond the weld tip...and... success. I'm happy now

[alan_thomas]

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ethel wrote:

Thanks to everyone who made a suggestion, tried it this afternoon with bigger holes (8mm), clean wire, slower wire speed and 'special' shroud set with the legs protruding beyond the weld tip...and... success. I'm happy now

To quote the immortal words of the 'A' Team -

"Its great when a plan comes together!"

- Alan

[Andy Rundell]

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alan_thomas wrote:

To quote the immortal words of the 'A' Team -

"Its great when a plan comes together!"

- Alan

I seem to remember them being pretty handy at welding/fabricating as well