mig and flux core tips and techniques, equipment, filler metal
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ajp89
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Hello all,

A first timer here and in need of a little advice. Technically a second timer because we were taught welding back in shop class in high school but so many years have passed, I do not count that anymore.

It may be a dumb question, but I have one regarding grounding. I know you’re supposed to ground the piece your working on correct? My question is, if the piece I’m working on painted, do I have to grind another section of paint off to ground it?

I am currently making a lawn roller out of an old air compressor tank and there’s a few spots I need to fill in from old fittings and such. When I go to weld on my first patch panel, do I need to grind off paint on a separate section of the tank to put my clamp on? (I have no welding table, I am doing this on my concrete garage floor)

Thank you in advance and sorry if this is a really dumb question.


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cj737
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Yes, grind to bare metal to ground and weld the patch panel. And please make sure the tank is empty and vented when you start welding it. (In case you forgot that part from HS shop class).
tweake
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you need to grind a nice clean spot to be able to connect the earth clamp.
a small trick is to weld a tab onto the work to give the clamp something to grab onto.

earth connection is very important especially for mig.
tweak it until it breaks
ajp89
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Thank you for the quick replies!


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Simclardy
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I try to weld without a ground all the time! Lol
Sorry
The ground is just completing the electrical circuit. So anything that conducts electricity is ok, anything else is....no bueno.
Cheers

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ajp89
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Just laid my first 3 welds. Here’s the info:

Hobart Handler 140
Set on 4/40
75% Argon 25% Carbon Dioxide
Set on 17 cfh
Hobart .030 solid wire
Pretty nasty 3/16” scrap metal (only thing I had in the garage to play with)

Here is the first:

Image

2nd & 3rd:

Image
Image

I’m please with these being my first 3 in about 15 years, and the last time I welded was with an old stick welder that was in pretty rough shape from the kids beating on it. Let me know what you think I can be doing better. Also, what are the little brown puddles on the weld?


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ajp89
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Just laid my first 3 welds. Here’s the info:

Hobart Handler 140
Set on 4/40
75% Argon 25% Carbon Dioxide
Set on 17 cfh
Hobart .030 solid wire
Pretty nasty 3/16” scrap metal (only thing I had in the garage to play with)

Here is the first:

Image

2nd & 3rd:

Image
Image

I’m please with these being my first 3 in about 15 years, and the last time I welded was with an old stick welder that was in pretty rough shape from the kids beating on it. Let me know what you think I can be doing better. Also, what are the little brown puddles on the weld?


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Simclardy
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It's not wetting out, or penetrating properly.
You have a nice steady hand. Is 40 the wire speed? Did you use the chart on the door

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ajp89
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Simclardy wrote:It's not wetting out, or penetrating properly.
You have a nice steady hand. Is 40 the wire speed? Did you use the chart on the door

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You are 100% correct, I went back and look at the chart and I didn’t have it set right. Yes, 40 is the wire speed. Looks like I should’ve had a little more voltage and speed at 5/45 instead


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ajp89
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Simclardy wrote:It's not wetting out, or penetrating properly.
You have a nice steady hand. Is 40 the wire speed? Did you use the chart on the door

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You are 100% correct, I went back and looked at the chart and I didn’t have it set right. Yes, 40 is the wire speed. Looks like I should’ve had a little more voltage and speed at 5/45 instead


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ajp89
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Image
Ok this is on 5/45, the correct setting according to the chart for 3/16”. Still doesn’t look 100%, maybe I’m moving too fast? This welder is rated at only welding up to 1/4” so maybe this is all it really maxes at?


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Its very rare where you weld a 2 pieces butted flat against each other like that because it gives you very little penetration.

What you want is a groove to fill. Grind a bevel onto the edges of those 2 pieces you have there so that when you butt them together you have a V groove along the joint. Then just fill er up.

If you do want a flatter bead pushing the weld instead of pulling it helps. Point the gun to where you're going instead of where you've welded

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ajp89
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JayWal wrote:Its very rare where you weld a 2 pieces butted flat against each other like that because it gives you very little penetration.

What you want is a groove to fill. Grind a bevel onto the edges of those 2 pieces you have there so that when you butt them together you have a V groove along the joint. Then just fill er up.

If you do want a flatter bead pushing the weld instead of pulling it helps. Point the gun to where you're going instead of where you've welded

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Thank you for the info! I will keep on practicing[emoji1306]


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Great job cleaning the scrap down to shiny bright metal! You have no idea how much this gets looked past when people are trying to diagnose problems! lol Beads look great just have to crank up the power! More WFS and more V until you get the edges to flow smoothly into the base material.
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tweake
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ajp89 wrote:Just laid my first 3 welds. Here’s the info:

Image
you need to clean the whole joint. with a but joint like that that means both side and right around to the back side.
for practicing on the flat try to grind it down more. you want the whole thing to be nice bright shiny metal.

while people say you can weld through a bit of rust, when learning you always want to make it easier on yourself. ie did you screw it up or was it the rust screwing up your weld?
eliminate possible problems from the start so you can put your best foot forward.

prep work is 90% of the job.
tweak it until it breaks
Simclardy
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What's the distance between your tip and the metal (ctwd- contact tip to work distance)

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ajp89
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Simclardy wrote:What's the distance between your tip and the metal (ctwd- contact tip to work distance)

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I would guess between 1/4” - 1/2”?


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ajp89
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Just made some patches for the lawn roller. Have a few small ones to make then I’ll try welding them in after a little more practice

Image

Image


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ajp89 wrote:
Simclardy wrote:What's the distance between your tip and the metal (ctwd- contact tip to work distance)

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I would guess between 1/4” - 1/2”?


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Don't guess. This is part of the reason people need to diagnose problems and ask for "any ideas?". :D You always need to be cognizant of your CTWD and make a conscious effort to maintain it very closely. For welding thinner materials, on regular short circuit mig, I aim for 1/4"; for thicker materials like 3/16"+ thick steel, then I aim for around ~5/16" CTWD to accommodate the larger amount of metal being deposited and a slightly longer arc length produced. 1/2" is typically too much; it reduces the amperage at the weld puddle, which can cause excessive "lumpiness", aka ropey beads. If you can maintain a steady 1/4" - 5/16" you'll see the better results immediately. Try it on scrap and report back.
Last edited by Oscar on Wed Apr 15, 2020 11:34 pm, edited 1 time in total.
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tweake
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with short circuit mig you can noticeable hear the difference ctwd makes.
if your not sure on what sound you should hear there is many good video's where you can hear the sound.
tweak it until it breaks
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