# Why Metal Won't Stick When Welding?



## Pmedic828

Hope everyone ate too much for Thanksgiving - now I'm back in my shop attempting to make a table support for my drill press.  I am using 3/8' CRS plate for a bottom support for my drill press as the cast table that I had fractured and I discarded the original table.  Here is my problem.... When I attempt to weld a piece of 3/4 sq thick walled tubing to the plate, I seem to get a good flow puddle between the side of the tubing and the base of plate.  After letting it cool, I picked the piece up by the tubing and it fell off and separated from the plate - the 3 other pieces of tubing separated after a slight hammer blow sideways to the tubing. 
I used a wire wheel to clean both the plate and the tubing.  Then I clamped the pieces together.  The ground clamp was attached close to the welds on the plate.  I am using a Lincoln 180A wire welder with the settings of "C" and "3" and it seemed to be hot enough.  When I attempted to re-weld these, I increased the amperage and wire speed and it burned thru the tubing really quick.  I had to plate metal back on the tubing and then attempted to grind.  I am using flux core 0.035 wire which is a quality Hobart wire.
I profess that I am not a professional welder - not even a novice - basically I can get 2 pieces to stick together usually but am now asking for help to remedy this problem.    Your thoughts gentlemen......


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## TommyD

Dissimilar metals? I've always brazed cast, not sure if the two can be joined welding.


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## Wreck™Wreck

Cast iron. Too much carbon.
An alloy of carbon and iron containing 2% or less carbon is known a "steel".
Above 2% it is considered "cast iron" which is not easily welded if at all. I have successfully welded very low carbon cast irons in the past using nickel filler material made for this purpose, preheating and slow cooling is necessary. At best it is not ideal.


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## Pmedic828

It isn't cast iron - it is CRS and steel tubing


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## TommyD

Maybe a pre heat on the plate


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## stupoty

Might be worth posting a pic of the weld, as you say crs to crs is normaly nice and easy (i only play wit a little stick welding) 

If you give them a rub with the grinder do they spark the same?.

Iv'e had issues wih the mill scale on crs causing some bad weld issues.

Hope somone can help,

Stuart


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## TOOLMASTER

180 ISN'T HOT ENOUGH


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## bigmojo

Are both the CRS plate and square tubing ground down to bare metal?  
Is there any milscale or other junk coating either piece?
Any porosity in the weld?
If you are burning holes in it then you are more than hot enough, which leaves me to believe it is poor wire (the hobart stuff is pretty standard, better than the lincoln junk thats for sure), or dirty materials.


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## kingmt01

I've seen all kinds of crazy stuff welding. One time welding I watched the puddles rolling away from the other piece I was trying to join. Craziest thing I've ran into yet. All the other pieces of the same metals joined easily. It was like a magnetic force pushing it away.

If I'm having trouble joining two pieces I'll weld a pass on each piece then weld them together.


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## RJSakowski

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


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## FOMOGO

RJSakowski said:


> 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


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## JimDawson

RJSakowski said:


> 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:


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## David VanNorman

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


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## Billh50

RJSakowski said:


> 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.


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## 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


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## 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.


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## 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.


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## 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!


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## 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


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## 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.


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## shoeboxpaul

I recommend you look at this site. Jody has been doing this for a few years and there is a plethora of info and videos. I am posting the link for his basic MIG tips.

http://www.weldingtipsandtricks.com/Mig-welding-tips.html

http://www.weldingtipsandtricks.com/mig-welding-tips-articles.html

If you sign up, he will send you a weekly video, all for free and there is no solicitation and your info is not sold. I think you will enjoy this site.
Paul


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## Bill C.

Pmedic828 said:


> It isn't cast iron - it is CRS and steel tubing



So if it is carbon steel then try cleaning all the dirt and grit off. We used to use a flex sanding disk on our hand held grinders to get pass the surface near the weld area or seam. In some cases we would use a hard disk and cut weld grooves for deeper penetration.  I like stick welding when I was in my apprenticeship. We were taught to use several different types of welders but once outside the training never touched one again.  

Good luck on getting your project finished.


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