Why Metal Won't Stick When Welding?

[FOMOGO]

When welding thick to thin, I concentrate the arc on the thick and briefly bridge to the thin. I weld sheet metal to much heavier steel that way. You should see a good puddle on the plate before you attempt to bridge to the thinner tubing. Weave back and forth with the bulk of time on the heavier plate.

Bob nailed it. Mike

 

[JimDawson]

When welding thick to thin, I concentrate the arc on the thick and briefly bridge to the thin. I weld sheet metal to much heavier steel that way. You should see a good puddle on the plate before you attempt to bridge to the thinner tubing. Weave back and forth with the bulk of time on the heavier plate.

Bob

:+1:

 

[David VanNorman]

You guys are right put the heat to the thick stuff and bridge to the thin stuff.

 

[Billh50]

When welding thick to thin, I concentrate the arc on the thick and briefly bridge to the thin. I weld sheet metal to much heavier steel that way. You should see a good puddle on the plate before you attempt to bridge to the thinner tubing. Weave back and forth with the bulk of time on the heavier plate.

Bob

Yep...this works well. I used that method to make this.

 

[fixit]

Almost sounds as if the electrical, ground, is isolated from the 3/8 plate. The arc is not going to the plate & the molten puddle is just laying on it, I have seen it before, grind a spot where the ground is connected to the plate and where the weld will be. Good luck.

fixit

 

[SWARFEATER]

you are running the puddle on top of itself, I've seen lap joints where the weld just peeled off like an orange peel. this can happen pushing or pulling the puddle, the arc is on top of the puddle and not penetrating the base metal. try moving faster and keeping the arc down on the base metal. maybe too much feed already.

 

[Billh50]

I agree with Stuart. Pics of the setup and welds would help a lot. Without pics we can all just keep guessing. Whereas a pic can tell us more.

 

[Pmedic828]

Gentlemen, thanks for your help - today I didn't let this problem get the best of me - I wire brushed another set of pieces and tried again - the weld flowed correctly, and the weld couldn't be cracked off even when I directly hit it with a ball hammer. Don't know what I or it was doing the last time, but I attempted to keep the heat on the thick metal and work it over the tubing and it seemed to work. Thanks everyone for the comments & help!

 

[brino]

...one other thing that was not mentioned....

If you typically weld with shield gas but then occasionally weld without (or visa-versa) it is very easy to forget to change the polarity of the machine too.

I typically do most of my MIG with shield gas as it's so much cleaner (less sparks, less smoke). This past summer I worked on a canoe trailer. For that I decided to save the cost of shield gas and switch to flux core, also since I was outside I was not as concerned about the mess. At first it didn't click why I was having trouble with the MIG tip getting hot. I reduced my duty cycle but continued. During a break I started thinking about why it was acting so different, then it struck me -WRONG POLARITY!

The welds with the wrong setup were not horrible, but the machine was set to higher current and the tip and torch were getting hot!
Since then I always stop and first double-think any problems. Do I have the machine set up right?

-brino

 

[NCjeeper]

What is your torch angle? If it is not 90 degrees or close to it you may not be getting enough heat into the weld.