welding

[bernadillo]

ive just bought a welder, but i haven got any experience in using one... i have had a go on some of the holes, but im not sure how good they have to be to pass....at the moment i cant hammer the patches off, and i cant get a screwdriver to chip off any of the patches so is this ok? (the welds look like bird poo because its a gasless one, but seems to be strong)

also does anyone know any good websites with welding tips?

[RNRMF]

Welds have to be continueous to pass an MOT, e.g. a solid line of weld all the way round the patch.

Darrens basic welding tips...

The only way it's going to work is if you are welding clean metal to clean metal. If you are patching some rust make sure you have gotten rid of all the rust so you are back to good clean metal. Also wipe the metal to get rid of any oil etc as it stinks and is toxic when it burns!

Make sure you have disconnected the car battery!

Check what is within heating up distance of what you are welding, e.g. if patching a sill, is there any carpet inside the car close by that will set on fire? Any door rubbers that will melt/set on fire?

Try and weld in as little wind as possible so the gas (cylinder from a gas welder, from the welding wire in a gassless welder) doesn't blow away.

Tack the corners of the patch on first. This is because the welds shrink and if you weld one edge down first the patch will end up sticking out and need to be hammered back down flat.

Weld with the nozzle pointing towards the direction you are welding so the wire is pushed into the weld not sort of trailing behind.

The best thing to do is practice on some scrap, experiment with settings. Wels to bits together and then break the weld apart to see how deep the weld penetrated.

Hope this helps.

[bernadillo]

i had a 5 min practice last night, and ive done 3 holes already...they seem to be ok and although dont look very good do seem very strong and are welded on all sides. i didnt disconnect the battery, but it still works (guessing its ok) and i will use all ur wisdom in my next patch.....

thanks darren

[chrisls]

My new methord of welding patches in is pretty odd.

I used to have problems trying to weld a patch into the floor say. The floor would never be straight, so there would be a gap between the patch and the floor making it so much harder to get a good weld.

Now, I make a patch about 0.75cm bigger on all side than the hole. (I always cut a nice hole with the grinder, nice straight sides making it easier to cut the patch). I then put the patch ontop of the floor, and drill a 2.5mm hole into the overlap. I screw in a 4mm self tapper through both pieces. I do this roughly ever 2 inches, or a bit more if the patch is on a curver piece of metal, ie the exhaust tunnel. This holds the patch right up to the floor in this example.

Then I tack in betwee the screws, undo the screws, tack where they were, and then seem weld between the tacks, seam welding over the holes.

Works so well, my patches are so much neater than they were 6 months ago.

[bernadillo]

i went to a few mot centres today, and none of them liked my work :( ... i had missed a couple of holes because i was rushing and the ones i had done wernt up to scratch... the holes i had spent a bit of time on tho were good and they said they were ok, but the ones i rushed earlier today will need grinding doen and repatching. im not too disheartened because at least i know some of the patches are up to standard and with a bit of time and filler (with a few tins of waxoil to cover it up) they should be ok... the other things they flagged up were no foglight, no horn and my battery wire was scraping along the floor...

one place didnt like black no plates or clear lenses

i will give ur method a go tomorro adn hopefully put it in for a propper test on thurs... thanks for the tips

[chrisls]

Probably just need a bit of practice, get used to the wire speed/ampage settings.

When I started I was trying to weld patches on to the rusty this bits of car. I used a low ampage and high wire speed. This gave me loads of blobs of unpenatrating weld. Not good.

Since then I've learnt it's fair easier/better to cut out a nice big hole so you are deffinetly back to clean thinck metal. So both surfaces to be welded and clean shiny metal. I now have the welder at a higher ampage and lower wire speed. I make the welds more slowly but continously.

[bernadillo]

my welder only has one wire speed and can be set on either high or low (burn holes or not work) settings....

ive been going over the dodgy holes again today and they are getting better, ive also been sticking filler in between the blobs and whacking a thick layer of waxoil....i will see what they think tommorow (hopefully tommoro)