Copper Backing Bars

[Wamsutta]

I have a 14 gauge steel mower deck with a long slit around the side of it. I figured I could back it with a copper strip and then MIG it up with my favorite loopty-loop pattern. A flexible strip would be even better for conforming to the curvature of the mower deck. Where do you guys get your copper backing bars/strips from?

 

[Sumboodie]

Hammer a pipe flat

 

[Wamsutta]

Brilliant ! I never thought of that.

 

[Sumboodie]

Brilliant ! I never thought of that.

Or can buy copper flat stock from Metal Supermarket, McMaster, etc, but it's pretty expensive vs "free" cut offs from the plumbing project you did 25 yrs ago and saved " just in case"

 

[Jswain]

Or can buy copper flat stock from Metal Supermarket, McMaster, etc, but it's pretty expensive vs "free" cut offs from the plumbing project you did 25 yrs ago and saved " just in case"

For moments exactly like this...

 

[readhead]

It doesn’t need to be permanent. Just a piece of copper or aluminum and move it along as you weld.

 

[dogdog]

They used to sell this at hf for like $10, seems like it’s discontinued.
You can find it at Amazon for more. Or google for welding spoon.

Amazon.com : welding spoon

 

[rsanter]

Buss bars out of commercial power centers

 

[imagineer]

Put a short piece of 1/2" copper pipe inside a short piece of 3/4" then as Sumboodle said, hammer it flat. Take your time and make sure there are no air gaps between the layers of copper or you won't get the heat transfer you want.

 

[sqznby]

Why not aluminum?
I have used copper myself and have plenty of 1/2 x 2 for certain jobs but for something like a mower deck aluminum would suffice.
It's more readily available and easier to manipulate to conform to whatever projects you're working on and just as good of a heat sink/backer bar.
Just a thought.

 

[dutchgray]

Buss bars out of commercial power centers

I have a couple bits I saved from going for scrap from one, 1/4" by 2"

 

[Ohmthis]

I also hammer copper pipes flat. But, when you need an oddball size, I cut open the pipe with snips and then clamp, hammer, twist to fit.

 

[imagineer]

Why not aluminum?
I have used copper myself and have plenty of 1/2 x 2 for certain jobs but for something like a mower deck aluminum would suffice.
It's more readily available and easier to manipulate to conform to whatever projects you're working on and just as good of a heat sink/backer bar.
Just a thought.

Aluminum melts at about half that of steel. it will melt under a steel weld, possibly adding porosity to your weld. Copper can possibly melt too, but not until about 1900*F.

 

[sqznby]

Aluminum melts at about half that of steel. it will melt under a steel weld, possibly adding porosity to your weld. Copper can possibly melt too, but not until about 1900*F.

Yes, you are correct but we're talking about a mower deck. Tight fit up and you'd have no issues with intrusion from the backer.

 

[BD1]

Why not get a piece of light gauge flat stock, form or clamp to fit, and weld it up . Just leave it there You could drill holes in the slit, plug weld to hold in place and just weld it up. I would wire wheel or flapper disc both inside and out.

 

[Firebrick43]

Bus bars work the best of the metals.

Graphite plate and rod even works better.

https://www.graphitestore.com/Graph...stitem_gs_applications/Welding-back~up-plates

https://www.mcmaster.com/products/welding-carbon-plates/

 

[Sumboodie]

I have a couple bits I saved from going for scrap from one, 1/4" by 2"

I had a few 8ft sticks. Gave them away when I moved. Along with a sheet of 1/4" stainless. Was HEAVY!

 

[Nortonscustom]

If you hammer a piece of copper pipe make sure to anneal it first. It'll be much easier to work with and you'll get better results. I have a roll of copper roof flashing. Use it for all sorts of stuff from weld backing to jaw pads on the lathe. Handy stuff.

As far as a 14ga mower deck repair just weld it vertical down. No backing necessary.

 

[NUTTSGT]

Hammer a pipe flat

I have a couple of pieces in my box for that purpose.

I've also used I larger brass drift for an appropriate sized hole as a backer.

 

[SlappyWhite]

Hammer a pipe flat

Pretty much, bonus if it is scrap copper pipe.

 

[dr_clyde]

I just buy bars of copper from the metal supply. I’ve been doing it long enough that I have quite a collection of copper bars, spoons, curved plates and all kinds of custom shapes and fixtures I’ve made. Copper is much more durable than aluminum and is surprisingly good at resisting spatter and the weld doesn’t want to melt in and stick at all.

I occasionally do long seams on thin stainless sheet metal and copper works really good as a heat sink/backer bar to prevent sugaring without a purge. I think my longest backer bar is like, 6 feet?

I usually buy 1/4” x 2” or 1/2”x 1” or similar. Mass is your friend on these, they only can soak up so much heat before they get scorching hot.

McMaster sells shorter bars and most metal supply houses can get you whatever you want.

I don’t like flattening pipe because it isn’t flat or consistent, you can get inconsistent results on some joints with that.


For a lawn mower I’d probably just use whatever is handy, aluminum would work for that.

 

[jblnut]

Buss bars out of commercial power centers

I do the same. I’ve scrapped dozens over the years and always save the copper parts. They come in hand so often that I have a few 5-gal pails of copper buss bars and pieces.

 

[i4ni]

In this case why not use piece's of welding rod with the flux broken off conformed to the shape of the crack on the inside and incorporate them permanently into the weld. This would beef up the stressed area.

 

[slowtwitch73]

You can get em off ebay for like 60 bucks... 3 piece kit (flat, 90 and combination and a handle) and dead flat. Doesn't need to be thick.

 

[Wamsutta]

Buss bars out of commercial power centers

Where you get those at?

 

[mike93lx]

Where you get those at?

Assuming you aren't stealing them or doing demo at commercial properties, you can likely grab a couple for scrap value at a scrap yard.

 

[rsanter]

Where you get those at?

I friend is a commercial electrician, he gave me a couple,of them

 

[danielbuck]

aluminum also works well, if you have some of that laying around. I keep some aluminum bars for backing while welding sheet metal.

 

[Crazyjake8493]

I've saved scraps of thick aluminum angle and flat bar over the years, for flat sections. For curved sections or if I really need copper I just hammer some copper pipe flat or to whatever profile I need.

I fixed a few mower decks last year. If your slit has a tight fit up, you won't need backing. If there's a gap or if you have to cut our rusted material then the backing strip would help.

I also have some various sections of solid aluminum and copper rods in 5/8", 3/4", and 7/8" diameter for fixing oblong holes in implements and equipment.

 

[ShadeTree55]

The copper tubing suggestion is the most economical way to go if the gap is wide enough to even need a backer. What I did not see mentioned in this string, though, is that the back side of the weld should be ground out to remove all porosity, if it is accessible, and then that side welded, too. The reason I say this is because I am assuming your crack is probably due to metal fatigue, and if you want a permanent repair, then the repair should be made to be at least as strong as the original, so full penetration with no weak spots, regardless of how good a welder you are.

 

[scooby074]

Do you even need it? I never use backing for most welds. Usually you can just vary the contact tip distance or make short pulses and fill some pretty gnarly gaps.