Bronze Brazing Nuts to Plaque

[Gordon Gould]

I have a neighbor friend who is an artist that works in bronze. Every once in a while he will bring over a bronze plaque and ask me to weld 10-24 nuts on the back so he can mount them in a wood frame he makes by routing out a recess. So far I have done about 10 of these, a couple at a time. I have a stick welder and an O/A set and I am just a door yard welder. I don't have much chance to experiment on a method and am nervous about screwing up his piece. So far the best method I have found is the O/A set and 1/16 bronze flux coated rod and catch the nut on 3 sides. I put a stainless screw in the nut an set it in the marker hole he drills after I grind the area off a little (Pic not ground off).

As soon as I catch one side I remove the screw. If I don't the screw gets stuck with flux or bronze wicks to it and I have to grind the nut off when I twist off the screw. When I braze the other sides with the threads open they tend to get crudded up. Most times I can fix it with a bottom tap I made by cutting off a standard tap. The job doesn't come out beautiful but it's best I can do and he is happy.

I keep thinking there must be an easier way and am looking for suggestions. Thanks !

gg

 

[bdhsfz6]

That plaque looks fairly thick. Can't you forget the nuts, drill holes & use a 10/24 bottoming tap?

 

[yomax4]

If you have to use nuts you can use a carbon stick instead of the bolt. Low fuming bronze won't stick to it. Silver solder would work as well or Phos Bronze if you want to use Mig.

 

[bdhsfz6]

Years ago, I added some nuts to a few bronze marine fittings. I put the fittings in a 500 degree oven for a half hour and brazed on brass nuts using silver solder and a Mapp torch.

Not sure if the oven would damage your plaque though.

 

[WranglerX]

If you have to use nuts you can use a carbon stick instead of the bolt. Low fuming bronze won't stick to it. Silver solder would work as well or Phos Bronze if you want to use Mig.

Was thinking this a good solution myself.... IF threads get a little flux in there, it can easily be cleaned with a "bottom" tap....

 

[MTGreen]

You could use weld nuts and keep the heat away from the threads

 

[California]

How about brass nuts, and silver solder?

 

[CalG]

50/50 solder, pre tin the steel nuts. Place them on the work while still hot.

CLEAN metal makes it easy.

 

[2manyrocks]

I apologize for not really understanding, but could you use brass rivet nuts instead and not do any welding? Amazon.com

 

[Langanobob]

I install a lot of similar bronze historical plaques. The foundry man casts raised bosses at each corner. All we have to do is drill and tap them. This is a lot simpler than brazing 4 nuts and you might ask your artist about it. Of course, it will complicate the casting work.

 

[Gordon Gould]

Thanks for the replies - some good ideas. I suggested silver solder the first time and he said that he would prefer I don't use solder ??? he's an artist..... I should have shown the front which is 3 dimensional not a simple plaque so it is to thin to drill and tap in many places. I have seen other stuff he does with bosses and/or drilled and tapped holes. He said he mounts these simple plaques all different ways and sometimes needs them flat on the bottom. I like the carbon sticks idea it will save me some cleaning with the bottom tap.

I only work on his crude stuff - thank goodness.

gg

 

[WranglerX]

Thanks for the replies - some good ideas. I suggested silver solder the first time and he said that he would prefer I don't use solder ??? he's an artist..... I should have shown the front which is 3 dimensional not a simple plaque so it is to thin to drill and tap in many places. I have seen other stuff he does with bosses and/or drilled and tapped holes. He said he mounts these simple plaques all different ways and sometimes needs them flat on the bottom. I like the carbon sticks idea it will save me some cleaning with the bottom tap.

I only work on his crude stuff - thank goodness.


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gg

Seems to me he does not understand silver solder is not just like plain old lead/acid solder...

Love this stuff....

Amazon.com

 

[jaxs]

If I understand the finished piece ,how bout brazing a flat head brass screw head on instead of the nut? Put molding clay on wood where screw holds need to be then press plaque with screws into clay to mark precise spot to drill holes then counter sink holes. Wood in contact with plaque will need only slight recess and bottom of wood will need recess for nut. Any melted filler drawn up into threads wouldn't go high enough to interfere when nut is screwed on from other side of wood base. As a bonus brass fasteners look better than steel.

 

[Fuddyduddy1952]

Beautiful work by the artist. It seems to me if it's going to be a permanent bond of bronze to wood epoxy would be the best choice. If he has bronze and wood scraps you could try different ones, once hardened give them a strength test.
From what I looked up original Gorilla Glue is very good and I've used a lot recently metal to wood. The only problem with it I've found is it swells like Great Stuff and has to be used sparingly.
I'm not sure why base would need to be screwed to bronze. If necessary again epoxy bronze to bolt or nut? There's no heat that way.

 

[Gordon Gould]

You guys are right in what you are saying but I can't see any reason to argue with a strong minded neighbor. It can lead to hard feelings for no reason. I'm doing him a favor and it is his work. Out of respect I do it the way he wants.

gg

 

[jaxs]

You guys are right in what you are saying but I can't see any reason to argue with a strong minded neighbor. It can lead to hard feelings for no reason. I'm doing him a favor and it is his work. Out of respect I do it the way he wants.

gg

Well gosh if that's the way you feel maybe you should stop "thinking there must be a better way and looking for suggestions".

 

[Gordon Gould]

I guess I didn't word it very well but I thought the carbon sticks was a great suggestion.

gg

 

[UncleW]

I had to braze on 1/2” captive nuts to 2 1/2” square steel tubing to make a tractor tool bar. I put anti-seize on a steel bolt and (like I understand what you’re doing), left it proud of the nut to locate it in the hole. As soon as I had it tacked in place, I backed it out till it was about 2 threads in. Kept flux out of the threads but was easy to break loose. Bottoming tap started easily and cleaned any bronze & flux out of the threads. I did mine with bare rod and paste flux but you can get the same effect by sanding some of the flux off a coated rod. Really don’t need a lot of flux on clean metal