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PostPosted: November 16, 2015, 7:03 pm 
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Since there isn't a "Lessons Learned - Welding" thread yet, thought I would insert a few comments here.

Things that improved my MIG welding:
- Got a good helmet with adjustable auto-darkening
- Added magnifying lens inside the helmet so I could get closer and see what was happening
- Mounted a little LED "flashlight" on the end of the torch to light up those dark recesses

and after much frustration with erratic feed of the wire:

- Switched the hose liner from a 0.030" wire-size to a 0.024" wire-size to match the wire I was using :roll:

I'm still not a good welder, but the above changes made a big difference in my results.

Feel free to move this post if a LL- Welding thread is started.

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My Car9 build: viewtopic.php?f=35&t=14613
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PostPosted: November 16, 2015, 8:15 pm 
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Joined: August 18, 2015, 12:41 pm
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Location: Seattle area (Woodinville)
If you were to build a second car, is there anything that you would do differently that you think that other builders would benefit to learn about. Conversely, is there anything that worked particularly well that you would recommend to others? Please confine this thread to Welding.

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PostPosted: November 16, 2015, 8:17 pm 
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Location: Seattle area (Woodinville)
Hang a plumb bob from the center of each end of the chassis when you do your finish welding and check it after each weld so that you can readily see if and how the chassis is distorting as you go.

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PostPosted: November 16, 2015, 8:21 pm 
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Joined: October 19, 2009, 9:36 pm
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don't drop it when turning it over to finish weld it, ask me how i know.

it really isn't that critical as long as it goes straight and corners the same left to right.

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PostPosted: November 16, 2015, 9:11 pm 
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Joined: July 4, 2006, 5:40 pm
Posts: 1749
Location: Novato, CA
I started out as a novice, one semester of gas welding at my local CC. What I learned about MIG:

Visibility is everything.

If you wear glasses for nearsightedness, weld without your glasses.

Don't tack square tubes in the middle of a flat. Tack at the corners.

Beveling edges really improves the strength of a butt weld.

Set a quota of 50 welds that you'll grind away and try again. It's okay to do more than 50, but try to do at least that many.


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PostPosted: November 17, 2015, 12:01 am 
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Joined: March 30, 2011, 7:18 am
Posts: 1054
Location: central Arkansas
Earlier threads on MIG welding:

Grounds: viewtopic.php?f=15&t=12678&hilit=welding

Nozzles: viewtopic.php?f=15&t=12677&hilit=welding

Build table and welding: viewtopic.php?f=39&t=12199&hilit=welding

(because I was too lazy to type it all in again)


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PostPosted: November 17, 2015, 12:04 am 
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Frayed pants equal hot legs...


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PostPosted: November 17, 2015, 12:17 am 
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Location: Carlsbad, California, USA
1) Echoing Nick47 above: you can't weld well when you can't see well. Get cheater lenses for your helmet if need be. They're cheap and readily available at all welding supply shops. They make a big difference.

2) Consider using an auxiliary light to illuminate weld joints if they are not easily visible. Some clever people here have attached them to their welding helmets. You may want to do the same. You may need to adjust the settings on your auto darkening lens (if you have one) to do so.

3) If it is physically possible, grind down your tack welds and put a slot in them (like you're making a groove for a screwdriver) with your grinder that runs in the direction of the weld bead. If you can't do that, make sure to weld to the tack, not from it.

4) Good fit-up is huge. If there's a gap, it's almost certain something will move when the weld cools. If one side of a joint has a gap, and you can't fix it, weld it last. Additional tack welds along the gap will probably help minimize movement. Grind and slot them if at all possible.

5) Cleanliness is also critical. Your joint should be bright and shiny, free of oil, paint and rust (1/2" from the joint in all directions) and cleaned with acetone prior to welding. Use chemical-resistant gloves when you use the acetone. They're cheap and many home improvement and hardware stores sell them.

6) When welding joins of square or rectangular tubing that meet at an angle, weld the long sides of the join first.

7) Flat welds (horizontal) are the easiest to do well. Assuming you're an amateur welder, try to turn your work so you're not doing a vertical or overhead weld, if possible.

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PostPosted: November 17, 2015, 2:54 am 
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Joined: April 19, 2012, 9:43 pm
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Location: Colorado
Biggest tips:

1) If it smokes; you didn't clean enough. Always clean the joint, inside and out, until shiny bare metal is visible with no contaminates. Acetone evaporates quickly but is flammable. Isopropanol is a bit slower to dry, but doesn't ignite readily, making it safer if you aren't a particularly careful sort. The dirt on the inside that you ignore will degrade the weld just like if it were on the outside.

2) As mentioned, tight fit up will reduce warping and produce more consistent welds. It takes a lot more heat (and molten metal) to cross an air gap.

3) Remember to breathe. I'm not joking. I always find myself holding my breath and have to stop and remind myself to breathe. Biggest hint is when I realize I can't move the torch in a smooth straight line. Most people literally hold their breath when they start up the arc and don't breathe until they run out of air. You want to do the exact opposite: Take a deep breath, and slowly exhale as you start the arc. This feeds your muscles fresh oxygen and will make you much steadier and smoother in your movement. Make it a ritual that you follow every time and you'll weld better.


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PostPosted: November 17, 2015, 4:53 am 
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Location: England
As above with vision and the cheater lenses, you cant always get your helmet clad head near enough to a joint on a space frame to see properly.
Plan ahead and position the welder so to keep the welders lead is kept as straight as possible while welding .
Blow out the liner with an air line frequently and keep the shrouds clean, a can of anti spatter is a must for both the shroud and work-piece.
Nothing worse than weld spatter come chassis painting time to chop up all your abrasives and fingers.
Get comfy, you dont stand a hope in hell of producing a good even weld unless you get your elbow propped against something. Worth a minutes thought.
Other than technique which I wont go into a successful weld is only the correct amps and wire feed Vs speed of weld. Too slow and you burn through, too fast and you are cold laying mig wire on top of the work piece with no penetration.

Below is a rusty un prepped piece of 3mm scrap welded with .6 wire . A butt weld, internal and external all done on the same amps. If the wire feed Vs amps is correct you can get away with very poorly prepped work and still produce a presentable strong weld. I have Lloyds two gas and arc certs ( long expired) but am self taught mig , these are just my observations from personal experience.

Image

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PostPosted: November 17, 2015, 9:16 am 
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Get your welder settings dialed in on scrap before you strike an arc on your work piece.

Keep a log of weld settings for different material thicknesses.

Anti spatter paste is your best friend for keeping the shield cup clean.

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PostPosted: November 17, 2015, 3:04 pm 
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Location: Waterloo, WI
When welding in awkward locations, weld from the hardest position to the easiest. In other words, you have to cover a distance of A to B. If B is in a more awkward position and A is an easy position, weld from B to A. The reason I've found this to be handy (and was taught this by a very experience old dude) was that if you start with the easiest section and move to where it's hard, you may move out of ideal position and make a much worse weld. Set yourself up as well as you can to get the most difficult part first. Then finish like a champion. 8)

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PostPosted: November 20, 2015, 9:04 pm 
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Joined: July 17, 2015, 1:56 am
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Location: Morrisville, PA
seattletom wrote:
Since there isn't a "Lessons Learned - Welding" thread yet, thought I would insert a few comments here.

Things that improved my MIG welding:
- Got a good helmet with adjustable auto-darkening
- Added magnifying lens inside the helmet so I could get closer and see what was happening
- Mounted a little LED "flashlight" on the end of the torch to light up those dark recesses

and after much frustration with erratic feed of the wire:

- Switched the hose liner from a 0.030" wire-size to a 0.024" wire-size to match the wire I was using :roll:

I'm still not a good welder, but the above changes made a big difference in my results.

Feel free to move this post if a LL- Welding thread is started.


All of this plus clean welding surface and good CLOSE ground contact when welding tubing. Electricity travels over the skin of the metal. You may think "Hey i have a lot of metal surface area" but when the metal is dirty or hot and distance will reduce the current you are trying to apply.

I use wire braid (wire harness or cable shielding) with a small hand clamp or two if i can't get the ground clamp close enough.
Attachment:
price_braid_shield_tinned_copper_wire_zhejiang.jpg
price_braid_shield_tinned_copper_wire_zhejiang.jpg [ 17.06 KiB | Viewed 2444 times ]


Also ditch the stock ground clamp and use the solid brass copper one. http://www.mscdirect.com/product/details/62043534

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PostPosted: March 10, 2016, 2:10 pm 
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Joined: August 12, 2012, 6:38 pm
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Location: worcester county, Massachsetts
For those of us who are using 135-140 amp MIG units, when working on thicker material - especially round tubing .125 wall and up - a red-hot preheat of the joint greatly improves the resulting weld.

round tubing seems to act as a greater heatsink than square tube, or flat stock for a given diameter. when I built the B-3 Mod 2 control arms, I preheated every joint red hot, and the welds flowed like butter.

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