penetration problems

[mk1joe]

hello forum,
im quite new to mig welding but its something i have been very interested in, i have finaly bought a welder (wolf 140 mig) to help with my suzuki sj jeep project and help me learn. so far i have had one really good practice go on sheet metal around 1mm but so far i havent been able to get any penetration, i have tried a few things like increasing the voltage and wire speed and slowing down the movement of the torch but to no sucsess.

the metal on the jeep is thiner than the metal im using to repair it, the repair metal is about 1mm. so far i have tacked the metal in place whith a lot of tacks but what i want to do is grind the tacks back and do a continuous seem weld, but im not sure if i will be able to get good penetration on the thick metal without blowing holes in the thiner metal.
to take back the tack welds i have bought some 40grit flap discs, but these dont fit in my grinder because the hole in the center is too small, i was under the impression that all of these holes where the same size, is there any adaption i can do or should i buy the right ones?

i am using co2 that came with the welder but would argon be better for thin metal? as the co2 ran out today, it was one of the small bottles and it didnt last very long.
thankyou for the help
joe

 

[Stereophoney]

you would be better with a co2/argon mix, as for your welds are you using a weaving technique ? i'm sure that would slow your movement a little and allow for more penetration

 

[Sparkey]

i have bought some 40grit flap discs, but these dont fit in my grinder because the hole in the center is too small, i was under the impression that all of these holes where the same size, is there any adaption i can do or should i buy the right ones?

Hmm, no i think you would better not mess around with that it could be dangerous!
What kind of grinder is it?

 

[mk1joe]

the grinder is a black and decker one, as for penetration ive tried slowing down and creating different weaves but the penetration is always exactly the same as in the picture, i can only think of going even slower but i think i will probably blow holes.

 

[gavuk]

We had this the other day with another poster ,he was using an extension lead which was causing a volt drop..what size wire are you using ?.....co2 should increase the penetration....you sound like youv'e bought discs for a 4" grinder not a 4 1/2" , you shouldn't really run a continuous bead it will cause distortion ...read the tutorials on here .........what kind of mk1?

 

[mk1joe]

thanks, im pretty sure im using 0.6, i thought it would be better because the metal is still quite thin, now youve mentioned it im sure 0.8mm would penetrate but what should i do when it comes to welding it to the jeep because im sure it would blow holes in the thiner metal. so far i have tacked metal to the jeep altough i expect it probably hasnt penetrated it still feels strong,

(looks a bit doggy) should i fill in the left over gaps with more tack welds?

another question is --if there is a small gap in the metal is there any way to fill it in whith weld or should it be left well alone ?

i bet your right about the grinder, thanks for all the answers!

 

[Sparkey]

another question is --if there is a small gap in the metal is there any way to fill it in whith weld or should it be left well alone ?

Yes, you can fill it (it looks neater) but it's a bit tricky to do, surely when you're welding thin metal....you risk to make the hole bigger!
Try small spots of weld (like you are doing already) but try to aim a bit more on the previous spot of weld and slowly make more spots overlapping each other until you have filled the gap...

Or you could use a piece of copper (piece of flattened copper pipe or something) which you clamp behind the hole, then you can fill it in...if you have good acces to the back of the weld that is!
You can do a forum search on this technique.