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Welding Questions - MIG

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bulletpruf

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Fellas -

Have had a Miller 211 for a few years and just used it for the second time today. Welded on a chassis stiffener on my Alfa Romeo. Went ok, but there are a few things that I could use some help with.

-I was welding chassis stiffeners on my 72 Alfa Romeo. The stiffeners are 16 gauge plates that have numerous holes drilled so you can plug weld. The perimeter is supposed to be welded, too.

http://www.alfaholics.com/race-part...alfaholics-chassis-leg-stiffening-kit-105115/



So, I stripped it all down to the bare metal and then painted the plates front and back with weld-through primer. Also painted the area on the car where the plate was welded, too, of course.

I was using .024 wire and 110 volts. You can't use the automatic settings with .024 wire; needs to be .030 or .035.

Welder was set up according to directions. It seems to be working fine.

The plug welding wasn't as easy as I thought it would be. Had to do some touch up work and also blew through in 2 spots. On the perimeter welds, I did pretty good when I was able to weld in a decent position. Think I was getting plenty of penetration based on what I was seeing.

See below for what I ended up with. I did a lot of grinding, of course. Pretty much all of the welds were sitting proud of the stiffening plate.



So, my questions --

-If you are welding 16 ga steel to 20 ga steel, what settings do you use? Settings for the thicker one? Thinner one, or do you split the difference?

-Should I go with .030 wire? I realize .024 is better for thin metal, but would be nice to use one size wire and just adjust my technique a bit.

-Should I use 220 or 110 voltage? I have both in the garage and the machine will work with either.

-What do you use to clean up ugly welds? I used a 4.5" grinder to grind the welds flat, but I need to work on the perimeter welds and the 4.5" grinder won't get in there. I have a small angle grinder, but not sure what attachment I should use on it. I have also heard that sandblasting can help some, too. This won't be a show car, but I really do want to clean up the welds so they're uniform and not noticeable.

Thanks!

Scott
 
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Zeke

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First of all the weld-through primer will fight you all the way — especially thin metals. Set your settings to the average and work from there. Start in the dead center of the plug and spiral one turn out ward. You should see a little bump. Leave it, it's stronger that way. If you don't like it, spray it with rock guard. Your perimeter welds look pretty good to me for a 2nd time user of that machine. Also, and this is very important, the liner in the hose has to be smaller for the smaller wire, not the factory installed one. Same with the tip, but I assume you know that. When the liner is too large, the wire tends to stutter and shoot out right after the arc is established. When spot and plug welding you don't need bad wire behavior. Nice and even flow and your welds will be easier and better.
 
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MoonRise

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re: 120V vs 240V power

Use the 240V power.

re: wire size

Sheet metal, 0.023/0.025 wire is fine. 0.030 can work on 16 gauge, but for me it is too thick to really work for thin 20 gauge stuff.

re: 16 gauge vs 20 gauge settings

You need enough power to melt into the 16 gauge (0.060") and not blow right through the 20 gauge (0.036"). Not so easy to do.

Usual welding rule of thumb is one amp of current for each thou of material thickness. So you 16 gauge is calling for about 60 amps but the 20 gauge only needs about 35-40 amps.

For thick and thin welding, usual procedure is to establish the arc on the thicker piece and 'wash' the molten puddle onto the thinner piece.

Or try putting a copper backer (aka 'welding spoon', or a piece of flattened copper pipe or the flat from a copper pipe cap held in place. Look it up if you don't know what I'm talking about.) behind the thin piece to minimize blowing right through.

re: welding primer

Clean the welding primer off of where you are welding. You can't really weld paint. And the low(er) voltage of the welding process you are working with really means you can't really get that voltage to 'blast' through the paint film. Result is iffy welds and/or a tough time getting the welds going or consistent.

For the rosette welds, check MP&C's thread here on GJ (yeah, all several hundred pages of it). He shows a nice walk though on some plug/rosette welds.

But you usually want to run the weld and end up with it just ever so slightly proud.

I usually like to get the arc on the 'seam' (perimeter of the hole) and spiral around that 'edge' and then spiral quickly into the middle (think soft ice cream cone swirl). That's when the hole diameter is big enough to do so. For a rather small hole diameter in the top sheet, start the arc right in the middle (onto the bottom sheet) and get the puddle started and than swirl around to the edge (again, ice cream cone swirl). YMMV, so practice a bit.

http://www.mig-welding.co.uk/plug/plug-welds-finished.jpg

http://www.mig-welding.co.uk/plug-weld.htm
 
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bulletpruf

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sqaurelizard said:
If you have 220v available Id use it any dual voltage machine Ive used worked better on 220v albeit generally on heavier material
Click to expand...

Ok, I'll try the 220.

A related question on 220 -- my 220 plug doesn't fit any of my outlets; is there a problem with using my 110 plug with an adapter in a 220 outlet? I also have a very large converter (drops 220 down to 110) in the garage and I can plug directly into it with no adapter to get 220.

And I didn't see that there was anything to do to the machine to run on 220 vice 110. On my grinder and drill press, both are dual voltage but you have to swap some wires to go from one voltage to the other.
 
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bulletpruf

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Zeke said:
First of all the weld-through primer will fight you all the way — especially thin metals. Set your settings to the average and work from there. Start in the dead center of the plug and spiral one turn out ward. You should see a little bump. Leave it, it's stronger that way. If you don't like it, spray it with rock guard. Your perimeter welds look pretty good to me for a 2nd time user of that machine. Also, and this is very important, the liner in the hose has to be smaller for the smaller wire, not the factory installed one. Same with the tip, but I assume you know that. When the liner is too large, the wire tends to stutter and shoot out right after the arc is established. When spot and plug welding you don't need bad wire behavior. Nice and even flow and your welds will be easier and better.
Click to expand...

Winner, winner, chicken dinner! I've got the factory liner right now. Thankfully, I have a liner for .023/.024 wire new in a bag on the shelf. I'll swap it. I've got the right tip.

Thanks!
 
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bulletpruf

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MoonRise said:
re: 120V vs 240V power

Use the 240V power.

re: wire size

Sheet metal, 0.023/0.025 wire is fine. 0.030 can work on 16 gauge, but for me it is too thick to really work for thin 20 gauge stuff.

re: 16 gauge vs 20 gauge settings

You need enough power to melt into the 16 gauge (0.060") and not blow right through the 20 gauge (0.036"). Not so easy to do.

Usual welding rule of thumb is one amp of current for each thou of material thickness. So you 16 gauge is calling for about 60 amps but the 20 gauge only needs about 35-40 amps.

For thick and thin welding, usual procedure is to establish the arc on the thicker piece and 'wash' the molten puddle onto the thinner piece.

Or try putting a copper backer (aka 'welding spoon', or a piece of flattened copper pipe or the flat from a copper pipe cap held in place. Look it up if you don't know what I'm talking about.) behind the thin piece to minimize blowing right through.

re: welding primer

Clean the welding primer off of where you are welding. You can't really weld paint. And the low(er) voltage of the welding process you are working with really means you can't really get that voltage to 'blast' through the paint film. Result is iffy welds and/or a tough time getting the welds going or consistent.

For the rosette welds, check MP&C's thread here on GJ (yeah, all several hundred pages of it). He shows a nice walk though on some plug/rosette welds.

But you usually want to run the weld and end up with it just ever so slightly proud.

I usually like to get the arc on the 'seam' (perimeter of the hole) and spiral around that 'edge' and then spiral quickly into the middle (think soft ice cream cone swirl). That's when the hole diameter is big enough to do so. For a rather small hole diameter in the top sheet, start the arc right in the middle (onto the bottom sheet) and get the puddle started and than swirl around to the edge (again, ice cream cone swirl). YMMV, so practice a bit.

http://www.mig-welding.co.uk/plug/plug-welds-finished.jpg

http://www.mig-welding.co.uk/plug-weld.htm
Click to expand...

Ok, I'll try 220/230/240 with the smaller wire (using the correct liner).

Washing the puddle from thick to thin makes sense to me. I'll work on that.

Understand what you're saying on the primer, but should I still prime the underside of the stiffener and prime the area where it's welded to the car? I'm just worried about possibility of it rusting since there's a small void in between the two. If I prime both, I can clamp the stiffener on and sandblast the primer from each hole.

I do have a few copper welding spoons; thanks for the tip.

I'll check Robert's thread to see what I can find on plug welds. I'll try starting on the inside and outside and see what works for me.
 
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bulletpruf

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sberry said:
That machine comes with the right liner and if you are not tripping the breaker changing voltage wont make any difference.
Click to expand...

I will double-check the liner and instructions, but I think I have the wrong one installed now.

Thanks

Scott
 
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sberry

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There may be only one, some of them use the same for all 3 sizes I think. Some could be 023-030 too but if its factory it should be right. The machine will run 023 the same on 120 as 240, an experiences,,, or maybe not,,, could turn it up high enough it could trip a 20 but I doubt it.
Where it shines is 030 which is the wire runs in mine. 22A @ 240, 2 x the input power.
 
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