I have antic culturally significant brass gongs that needs to be repaired. They got holes in it that need to be filled. Any good suggestions from anyone?

Post a picture and how did the holes get in them?

warren
http://www.flickr.com/photos/metal_recipes/

If the gongs are truly antique and culturally significant, then repairing them by any means other than those perfectly consistent with the period of actual manufacture would virtually destroy the value of the pieces. True conservatorship would indicate doing nothing more than the minimum necessary to prevent further deterioration, but no "repair" at all, unless absolutely necessary to preserve the pieces. Then those repairs must done in the aforementioned historically consistent manner, usually plugging and peening followed by surface dressing with scrapers and gravers.

Hi there -

I'm making a birdcage dress out of brass and am having some trouble getting the 1/16" round rod to attach to the 1/2" x 1/8" strap. It seemed to be working fine when I was doing it on a flat, horizontal surface, but now that I'm attempting to do it at some weird angles I'm just making a mess.

I'm currently using Radnor Stay-Silv 5 and white brazing flux.

Photos here of the strap I'm trying to attach the round rod to (I'm trying to create the actual 'cage' with round rod going horizontally):
Birdcage Dress 1
Birdcage Dress 2

Thanks so much in advance for any advice. Brass is a worthy opponent! I'm imagining it will take some wrangling, but I'm hoping that there's some sort of solution.

Cheers,
Kasey

one article i read is that only brazing is possible because zinc and copper melt at such different temps. (zinc boils well below copper's melting point). another article i read gave the melting point of common brass alloys around 900F. i would like to find out once and for all if a true fusion weld is possible because i have a project that i'd like to use a nice, pretty TIG weld on, and i'd sure like to use brass. (it's a musical instrament)

That is pretty much the definition of brazing.

It is NOT welding
but it is effective bonding.

The steel melts at almost twice the temp of the brass. Indeed some of the brass will boil off or burn before the steel melts.
What happens is that you clean and chemically activate the surface of the iron and then con the brass into sucking on it. The brass gets all tangled up in those little active chemical hooks on the surface and stays stuck. VERY stuck.

Gene Olson
Sculptor
Elk River, MN

Hey Gene -
You have a way of putting thigs that gets through to me.

Thanks,
Rick Crawford at Smoky Forge

It must have been the green fairy

Gene Olson
Sculptor
Elk River, MN

Hi
i am trying to cast brass around an iron core.. this is to save brass and get some strength in a 20mm diameter rod that is suposed to look like a twig. the twig looks i get by wax casting brass around this iron rod.
i am having a problem in assuring adhesion between those 2 metals, does any of you have any experience in this process?
i do a lot of lost wax casting and sandcasting already.
Jakob

Jakob,

I'd suggest that you use stainless steel rod, rathe rthan mild steel. The heat of the burnout and casting is going to scale the steel and possibly result in later problems. Stainless will have a tighter, thinner scale and the shrinkage of the brass upon cooling should make it pretty darn secure.

I seriously doubt that there is any way at al lto get a chemical bond between the two by casting the brass around the steel. That saidm brass and bronze have been cast around steel armatures for centuries with good success, so I wouldn't worry too much about it.

In practice, what I would do is forge the brass to have a twig-like look and at the same time work harden it. Some brasses have tensile strengths approaching that of steel and should be pretty strong in a hardened 20 mm (.80") diameter section. I use silicon bronze for similar purposes and it is plenty strong enough for everything I need it to do. It forges beautifully and can be TIG welded with no visible joint.

I like Rich's reply and can see that he has had more experience than I in this sort of project. Nonetheless, I would be tempted to at least test doing your project by casting around ordinary (and CHEAP) rebar... relying on the MECHANICAL bond created by casting into the heavy texture on the rebar.

If you only need the coloring of brass though... you could simply forge the whole twig in steel and then limn it with a brass brush at black heat. I do that often and the look is quite excellent and pretty durable too. I also sometimes use bronze brushes for limning but find that is more work as the bronze has a lower range of useful transfer temps.

One more idea that I'll toss out in case you are interested... I find a fair amount of copper clad steel ground rod material at scrap dealers around here. I have NOT tried forging this type material but I think one day I will. If you need more gold colors than the reds of copper it is easy to heat patina for gold on copper surfaces.

BIgfootnampa,

That's an excellent suggestion to use the textured rebar. The heat of casting brass around it will change its tensile strength due to partial annealing, but that shouldn't be a concern unless you're building bridges. :-) The texture will guarantee a strong mechanical connection with the casting.

Since I'm a primarily blacksmith I usually try to find a forging solution to problems rather than casting, fabricating or whatever. I like hammering on metal!

As for forging those copper-clad ground rods, I think you'll find them very frustrating. I tried it once many many years ago and discovered that the copper cladding was so much more ductile and malleable than the steel core that it tended to pull away from the core during forging. Like I said, that was a couple of decades ago and I was not nearly as proficient at forging as I am now so I might have better results if I tried it tomorrow. So, you should give it a try and let me know how it goes. (grin)

One possible technique that we didn't mention was metal spray coating. If you have an acetylene torch and a compressor you can get a metal spray torch and some brass powder and try that. It's something I've been wanting to do someday but haven't - yet.

Rich

Newbie here............

Definition/demonstration of "limning" please?

I have been asked if i could build a 20 foot ash tree out of copper. I have tried fridge copper tubing which works well but too malible and not the look i think is wanted. Any suggestions Sé

Get a very big TIG welder and hope the client has a whole lot of money. Nothing to do with welding brass.

www Metalrecipes -- heat and beat to the desired shape, repeat as necessary.
warren

what about roughing it out in steel and melt the copper on with an oxyacetylene torch as if you were brazing. Take care not to overheat the steel and work from shiny metal. Copper may look like it has fused to steel but if the steel is already oxidised the copper can just peel off.

As with steel, and bronze, you can directly sculpt the copper to create bark like textures and other details. it's about keeping the weld area at a very precice temperature. copper doesn't have much of a meting range, unlike its alloys, and is very heat conductive. ie you can melt a big hole in it!

Yes, I use silicon bronze to weld mild steel to brass.
www.pattiebyron.com

I will have to look up silicon bronze melting point. Most brass I mess with is 260 and I believe it melts real close to the temp of my bronze brazing rods. I am considering applying a glob of braze to the steel I am about to join then securing it to the brass and cautiously apply heat. I have burned holes in brass a couple times as I am a novice.

Also I notice common brass alloys don't "melt" so much as get covered in greenish yellow dross and collapse when overheated. Using alot of flux might help too.

I learn more about metal working when I mess something up.

Are you talking about the film over the puddle? Yes it will do that and flux helps, you just need to move the torch tip around to get it swirling, note if you have the proper size tip you should have a small puddle and not burn holes, but the brass will blow through if too hot, than stick in your rod pushing through the film the puddle should melt some rod and if the other side is hot too the puddle should just flow out to perform a joint.

www Metalrecipes -- heat and beat to the desired shape, repeat as necessary.
warren

Dunno about any brasses that contain magnesium, but I TIG weld brass using DC, not AC. HIgh amps to start, then back off after you get liquidus at the puddle. Tough to get a color match due to the low melting metals gassing out, but that's the story with brass.

Rich