Joining thin sheet metal

[Richard.]

If your seeing the gap between the two parts once you take off the weld cap then your not fusing into the plates at all. Yes the Tac on tac thin metal technique is a proven method for such things but the idea behind it is you stop at the point just before you blow it then restart overlapping the previous tack by 1/3 but you need to restart it while that tack is still glowing, travel along and again only stop when it’s about to go. This ensures good fusion. On 0.8 you should see it clearly punched into the back side. Going down is a good method but you must ensure you set it hot enough because it’s not a good fusion welding position and if your not punching right into it then you’ll have the same trouble when you grind it back. Set up some practice bits and keep pushing the power up until you start blowing through then back it off till it’s on the edge. Then your half way there.

 

[charles_darwin]

Hi guys,
Thanks for all the input. @gaz_moose I welded with Argon + CO2. @Paul. thats probably the smoothest weld i've ever seen, will have something to aim for. I think I need to lower my wire speed to achieve such a low profile & consistent weld. @Richard. I was thinking that I need to keep the welds glowing but didn't stick with it throughout, will look forward to applying these tips!
Regards,
Charles

 

[charles_darwin]

Hi folks,
I'm off to the metal workshop tomorrow, i'm wondering what kind of joint from these three I should be doing on a 1.5mm mild steel sheet? Tomorrow I am only practicing my welding, so will be making a 40cm cube out of the 1.5mm sheet. Initially I was thinking the full open corner joint but upon drawing up my plans I started to think maybe the flush corner joint could be better? @Paul. I am wondering if you remember what joint you did in that example you posted above?

 

[Paul.]

@Paul. I am wondering if you remember what joint you did in that example you posted above?

I used an open corner, but on 1.5mm material you should be able to get sufficient penetration however you do it, if using an open corner make sure that there is no gap or you will be blowing holes

 

[Pigeon_Droppings2]

Personally I think I'd just cheat and just add a corner of steel tack welded on the inside so the joints end up being double thickness....is that possible?

 

[Paul.]

Personally I think I'd just cheat and just add a corner of steel tack welded on the inside so the joints end up being double thickness....is that possible?

Why complicate it, its a basic joint, one of the most common in sheet fabrication and one of the first you will learn on any training course,

 

[charles_darwin]

Thanks for the replies, I'll probably go for the open joint. Will post some photos of the work!

 

[Pigeon_Droppings2]

Why complicate it, its a basic joint

Depends I guess....I mostly weld 0.8mm steel and I doubt I could make a neat crisp corner on that pyramid without cheating. Agree if yo have the skill and the kit to do it then it's easy maybe....

 

[charles_darwin]

Really pleased with my welding progress yesterday, I was getting good fusion and not such an ugly weld. Penetration was fine, even did a test on the vise to see if the weld would break and sure enough it didnt. 1.5mm was a world of a difference between the 0.8mm but also felt a lot more confident welding downhill in a continuous streak. Thanks to everyone that contributed to this thread, I had some of the comments in mind while in the workshop. Just still need to figure out how to treat the cube's corners properly to not feel the need to give them a second welding pass.

 

[charles_darwin]

Hi all, my journey continues, today I was welding an object that required welding an inside corner. Oddly enough, no matter how many tries and how strong the settings on the mig (argon/co2) I couldnt get the proper penetration, and on testing with the vise the weld cracked and split from the sheet metal. Any suggestions on how to make this fuse (ideally to the degree of my outside welds posted above) instead of just laying a fillet?

 

[charles_darwin]

I was using a Fabricator 3 IN 1 181 li MP at different settings, even tried at '6' and '6' on my 1.5mm sheet and still not penetrating and I wasn't going fast either... just surprised me thats all!