Brazing or welding thick copper?

I agree, if the whole thing were made of heavy stock like that it would eventually become a humongous radiator. I had the (perhaps erronious) impression that most of the stock would be considerably smaller, just the outer frame was the heavy stuff.

I noticed that there are actually phosphor bronze electrodes for SMAW. According to the datasheet

these rods could be used to weld copper. Has anyone used these? In any case, I'm sure I would have to buy a minimum of 10lb and I don't need that much.

I think I'm going to try brazing, though.

I have some Stay-Silv 56 from another project. Would that be a good alloy? Or should I use their phosphor copper alloy? I guess one would use the phosphor copper for better color matching? However, using the staysilv 56, I would only have to get the copper to 1200F instead of

1400F.

If I braze the copper bars, would a mitre joint be the appropriate joint? It seems there would be more surface area than a butt joint, but it still seems like there should be more of a mechanical fitup for brazing.

I'm beginning to think I got in way over my head on this one. The gate was supposed to look something like this:

+--------------------------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +--+--+---+---+---+---+--+-+ |**************************| |**************************| |**************************| |**************************| +--------------------------+

with the bottom portion a copper panel attached with brass rivets. So there would be three horizontal members and two verticals. The spikes in the center are .5"x.5".

As far as sagging, I figured if the bottom panel was tightly attached, it would add some rigidity to the gate.

I could use the copper for some other projects. I'm thinking now that this project just isn't going to work with the tools I have.

Thanks for all of the insight and help.

-Aaron

I think that a lap joint would be the best joint for brazing. Wayne Cook Shamrock, TX

Well, I wouldn't give up without at least a test. You say the sheets will be riveted on. No brazing there at all? Then you'd definitely want to put that on LAST. So, you are going to have the spikes unsupported for most of their length? Some delinquents might be able to bend them and make a total mess of the thing. I guess once the copper work hardens in the weather, that might be real hard to do, though. I think a person could do that in the annealed state.

So, these spikes are welded just into the middle crossmember? Or do they pass through into the bottom horizontal? If the former, I think maybe you could assemble the spikes to the crossmember, build the square frame, and then you only have two difficult joints to do. Those might be possible to do with sufficient heat sources and insulating blankets. Anyway, you ought to try preheating and then TIG welding a sample of the material. If it seems a breeze, you might try to push ahead with it. If the simple test proves a very difficult job, then you know that it is going to get worse as the parts are assembled.

Keep us informed, some info on what turns up is always useful when trying to advise on unusual projects like this.

Jon

I did some brazing a few weeks ago - been a long time - and long re-learning...

It was on copper sheet - 32oz and 64oz - 110 copper - 99.99999% IIRC. It was a rough go - using lots of oxy on it. It was copper to copper with bronze filler and a small torch.

What I found was - used some borax type flux that was around the filler - but what did the trick - paint the area with electronic flux - then braze on top of it. Get a nice puddle - and naturally alloy - then add the item that needed to be added. This was while it was hot and fluxed. The white flux around the filler worked to a lessor extent but worked only in protected air space - no air flow.

Copper was a pain in the neck. I did the exact same thing with the sheet of steel and the add on part still copper pipe. Beautiful flowing glob - and adding the copper, it froze the top, but adding heat, it flowed around both nicely.

I think the real trick is this : Must get the brazing material to whet on the surface and flow. Once it is on one then the other is the job.

Might be best to do two jobs and then heat them together.

Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Wayne Cook wrote:

Yeah, I'm curious too. If I had some chunks of copper I'd have tried it -- have the blanket and TIG, but no copper.

I would not give up without thinking about it a little more. I know you have the design already done and approved, but do the spikes have to be square?

I am thinking 1/2 inch copper pipe with 1/2 inch steel rod inside for the spikes. And a pointy copper arrow head added to the top afterwards. If it really has to be square, then make a tapered steel piece and pull it through either 1/2 or 3/4 copper pipe. Obviously this will take some experimentation. But I think it could be done. Start with copper pipe that is longer than you need and braze on at one end something to hold it. Use 1/4 inch steel cable and a come-a-long to do the pulling. You may have to make several square tapered steel pieces of increasing size and anneal the copper pipe after each pass. And of course use lube. I can see you now doing this between two trees.

If you can make square copper tubing, then you can use two of them brazed together ( or welded ) to make your 1/2 by 1 rectangular bit. Or if you can use rounded pieces then two copper pipes side by side or spaced so the " spikes can fit between.

Whitman college in Walla Walla, WA has some gates made of copper pipe that are attractive. As I remember they are of quite a bit bigger pipe and so probably don't have the steel inside.

Dan

" snipped-for-privacy@krl.org" wrote: ...

...

I think pulling the pipe through two sets of rollers (one set vertical, one set horizontal) would work better than using the interior square mandrels you suggest.

I don't have a good size chart handy for copper pipe, but imagine that 1/2" type M copper pipe is 0.625" OD and 0.569" ID. So the inner periphery would be 1.788", and the outer

1.963", which would give an inner width of 0.447" and outside width of 0.491". Half-inch rod wouldn't fit inside, but 7/16" would. Or perhaps use 4 sets of rollers angled at 45 degree intervals, and roll an octagonal shape with .5" steel rod already inside.

-jiw

Last night I did a little experimenting. 3/4 inch copper pipe will square up to fit over 1/2 inch square steel tubing. I just beveled the end of a piece of 1/2 square tubing. Annealed the copper by heating it dull red and then after it cooled used a dead blow mallet to square it a bit as I pushed the steel tubing inside. I only did a short piece, but it was pretty easy.

I agree rollers would be the ticket, but not sure it would be worth the trouble for less than 100 feet of squared up pipe.

Dan

So say I wanted to squaring a 4 foot section of pipe, what would be the best way to heat the entire section? Hmmm, I guess annealing 1' sections and then welding them together would be doable, although time consuming.

I just got off the phone with Weld Mold. They make SMAW electrodes for tough pitch copper and their technical person seems to think it would be fairly easy to weld the copper bar using their 4333 electrode with a pre-heat of around 500 degrees.

So if brazing doesn't work, I might just try their rod. I'm feeling pretty confident that I can get this all worked out. I'll probably start working on this project in the next two weeks and will give a status report then.

To anneal copper you just heat it to dull red and let it cool or quench it. The rate of cooling makes no difference. The only way to harden copper is to work harden it.

So I would anneal the whole length of pipe. You don't have to get it all red hot at the same time. Just start at one end and get that red hot and work your way down the pipe. As you square it, the copper will be work hardend. But only the part that you have done something to work harden it.

Using a mallet works, but the square copper tubing shows that it was hand done. It does not have factory looking flatness. Could be a good thing or a bad thing. Depends on the look you are trying to achieve.

Stop by Home Depot, Lowes or wherever and get a ten foot length of 3/4 copper pipe and try a couple of experiments. Copper pipe is not too expensive.

Dan