Copper Brazing

[ChrisBen]

I'm making a new double blade paddle this week.
http://i143.photobucket.com/albums/r133/loki59/paddle.jpg
http://i143.photobucket.com/albums/r133/loki59/paddle1.jpg
After roughing out one end I thought it would look nice with a bit of copper to protect the tips of the blades. I made up a paper pattern and was satisfied with the look.
http://i143.photobucket.com/albums/r133/loki59/paddle2.jpg
http://i143.photobucket.com/albums/r133/loki59/paddle3.jpg
I'm thinking of inlaying the copper flush with the wood and using epoxy rather than brads to attach the tips. I have a couple of questions on how best to do this. Does anyone have any recommendations for any particular epoxy for copper to wood? Also, since it is going to be epoxied, are there any recommendations on whether to braze the copper seems together or would lead solder in the joints be strong enough? I'll probably use some copper flashing to make the tips so would I need to use mapp gas or would propane be hot enough for brazing that thin copper?

[kc8pql]

Lead solder would work fine. If you want to get fancy use silver solder. I think you may melt the copper if you try to braze it. Copper flashing is pretty thin to inlay. I probably wouldn't go to all that trouble and just use copper tacks. It will do the job just as well and from 3 feet away you won't be able to tell how you did it. I'd stick it on with something like 5200 rather than epoxy.

[merlinron]

chris, soldering a joint like that (more or less a long butt joint), is never going to stay together. a few bangs on some rocks and the tin center strip which is you endgrain protection will start opening up.
as long as you are using flashing, you might want to make a new pattern that has a little bit of material to overlay the sides a bit. or simply add a bit of width to the end grain strip when you lay the copper out. then peen it over the side panels and solder it. it will be many times stronger that way. soft solder doesn't have much strength in a joint of that type, it really supposed to be used in a lapped joint so there's some surface for the solder to hang on to.
to get the lap part ot peen over nice, make a female mold of the end of your paddle the same thickness as the paddle.... like the cutoff from a bandsaw, of the end shape of your paddle. push that uo tight against the end of the paddle with the copper in between, then peen the lap over. the female mold will keep the copper nice and true on the end of the paddle. it's alittle more work, but it will make the end lap nice and neat.

[George Ray]

On oar and paddle blades I like to edge drill the long flat near the tip and drive in a snug fitting 3/32 or 1/8 piece of brass brazing rod to prevent warp/splits at blade end.

p.s. nice metal work

[Cuyahoga Chuck]

If you are going to braze you need an oxy-acetalene flame to get the required heat. Silver-solder requires less heat but whether anything less than oxy-acetalene will work is beyond my experience.
The next problem is how thin is the stock? Indiscrimantely playing a 2000° flame on copper that is thin gage or small in cross section could fry the copper.

[The Bigfella]

You can silver solder with a propane flame. I just silver soldered 8 brass fuel line fittings onto some 15mm stainless steel fuel lines. The first six were done with oxy - but the last two fittings were on backorder, so I gave them a go with the propane, rather than transport the long line on another 60km round trip. Worked fine - just took longer to get enough heat into the fitting.

[merlinron]

annealed copper flashing doesn't take much heat to brittlize. it's intended to be soft soldered, done the traditional way with a hot iron and solder. i would use potable water solder as used by the plumbers for sweating copper water tubing and it's fittings,...the stuff used in a house.... even real silver solder might need too much heat for the flashing, it's pretty thin. potable solder is at least 10 percent(IIRC) silver. just enough to give the soft solder a little more tensile strength, but still melts at a very low temp. none of the solders will be strong enough to withstand the abuse the end of the paddle will get if the joint isn't lapped as i described, though, the amount of solder actually holding the two pieces together is too thin for solder of any type to have any strength. solder gets it's strength from the surface area it has to hold on to. that's why solder joints are said to be "sweated" together. properly, capilary action migrates the solder over a large area, such as in close fitting tube and sleeve, like water tubing in a house..... a lapped joint..... to gets it's strength, where the solder is just hilding the pices in place and taking up the play. the thinner the actual layer of solder in a joint, the stronger the joint is. two thin sheets of copper butted together and soldered relies on the streangth of the material joint them and solder won't hold up in that situation...... it's the exact reason why someone figured out how to melt the same material as the pieces are to join metals.... welding.

[Mrleft8]

Far as I know nothing sticks to copper (glue-wise).

[ChrisBen]

Thanks all, gives me something to think about. When I thought of this yesterday I figured I'd just run down to H.D./Lowes and pick up a couple of pieces of copper step flashing for a few bucks to play around with. HD, "No we don't carry it but can special order it." Lowes, "We don't have it here but can get it from one of the other stores next week. How big is the roof and how many rolls of 20' at $30.00 + per roll?" So I went online and found this place,
Order Copper 110 Plate in Small Quantities at OnlineMetals.com (http://www.onlinemetals.com/merchant.cfm?id=1118&showfrac=yes&step=2&showunits=inches&sortby=od&top_cat=87)
12" x 12", 12 - 16 0z, about $12.00 + shipping, just what I'm looking for. My original paddle lasted 15 years till I let my Brother use it last summer, he stepped out of the canoe in knee high water using the paddle as a walking stick, jammed between some rocks and snapped about 1/3 of the blade off. I'm generally a little more forgiving with my gear so this is really more for looks than protection. I was kind of hoping that an epoxy would do most of the holding at the joints, rather than the solder/brazing.
Hey Lefty, nuttin works? How about kc8pql's suggestion of 5200 or the like?
Thanks

[Bill Perkins]

You could cut to your pattern as if to inlay copper sheet ,then fill with a very thick mixture of WEst copper powder and epoxy.Work down flush with files and scraper , renew at the tip as required .Not exactly the same look of course , but you've already have a modern look I think .

[Todd D]

Might I suggest that you use brass rather than copper. Brass is not quite as maleable as copper, but it is considerably stronger/tougher. I would also silver solder the joints. They will be stronger than the brass itself. You can buy 3"x12" pieces of brass sheet in a variety of thicknesses at any good hobby shop for about $3-$5 a sheet. The silver solder is a bit harder to come by, but is worth the extra money if you ask me. I use an oxy-propane torch for silver soldering. The type you see in jewelry stores. I routinely silver solder brass as thin as 0.010" with no problems.

As far as attaching the metal to the wood, you could epoxy it with West System G-Flex, but I think you will need mechanical fasteners (brass brads or small brass screws (available at the hobby shop).

Looks like a fun project.

[ChrisBen]

You could cut to your pattern as if to inlay copper sheet ,then fill with a very thick mixture of WEst copper powder and epoxy.Work down flush with files and scraper , renew at the tip as required .Not exactly the same look of course , but you've already have a modern look I think .Thanks Bill, just went to their site looking for that. I didn't find that particular stuff but I did find this,

"By Brian Knight

We have performed tens of thousands of adhesion tests over the years and many of these tests were done on metal surfaces. Below is a summary of tests done on a variety of metal surfaces and done with a variety of surface preparations. As you look at the chart, notice the surface preparation that gives the highest number.

All the tests shown below were performed using a PATTI (pneumatic adhesive tensile test instrument) meter. We chose this test method as our default adhesion test method about 14 years ago because it yields consistent results, is relatively easy to perform, and is economical. The results shown below show the tensile strength of a glue-joint. Not all joints are stressed in tension, so consider the data to be comparative, not a specification.

Most of the tests were done with WEST SYSTEM® 105/205 or 105/206. Most were allowed a two-week room temperature cure before the test was performed."

So I guess if it will bond copper to copper it should work as well on copper to wood.

[George Ray]

I suggest in a perfect world that the tip of the paddle that will be behind the metal be saturated with thin epoxy and then bed the copper/brass tipguard in 5200.

[ssor]

Take a look at Harris "Blockade" silicon copper brazing alloy. Used in the refrigeration industry and used by me in place of silver solder alloys. If roof flashing proves to be too thin consider splitting 1 1/2 inch copper tubing and annealing that and shaping it to your needs.
I never heard of heat causing copper to become brittle. Some copper alloys become hot short if heated to much while attempting to forge them.

[ChrisBen]

ssor, that's what got me to thinking about this whole thing. There is a short piece of 3/4" copper tubing lying on the workbench and I thought about making a wood blank out of white oak the same size as the paddle blade, cutting open the copper tube, heating it up and beating it around the oak form. That would eliminate the need to solder or braze any edge joints but I then thought that the flashing would be so much easier and quicker. I have a length of 1" brass tubing about 4' long that I just wrapped my paper pattern around, that's big enough for what I want. I think a piece of copper would be easier to form but since I already have the brass, I may do some experimenting today.
Thanks

[ssor]

Crisben, The brass can be annealed the same as copper and it will also work harden.

[P.I. Stazzer-Newt]

Back in the seventies - when serious competition slalom paddlers used wood - some of the makers used to wrap the tips (square ended) in 20swg aluminium which was folded in place and rivetted.

This was largely a waste of time and effort - without the metal wrap, the tip of the blade would get chewed - with the wrap, both the wood and the metal would get chewed - in about the same time.

What is worthwhile is the cross-grain piece scarphed in place.

[Alexander2]

If you wish to use epoxy to bond copper call West System and ask for advice. Its possible but needs a special procedure to get a good bond.
I bonded 60 sq. ft. of copper sheet to plywood and it worked but it was a challenge.

[ChrisBen]

Hey A2, feel like sharing?;)
I made up an oak blank and spent a couple of hours heatin, beatin and bangin on some 1" brass tubing.
http://i143.photobucket.com/albums/r133/loki59/form.jpg
I'm sure if I spent enough time at it I might get all the ripples out of the area of the bend. On the other hand if I were to cut along this red line, I could save a lot of time and get a better result. Then, just fasten with brads in the traditional manner.
http://i143.photobucket.com/albums/r133/loki59/cut.jpg
I took a piece of aluminum step flashing cut to my paper pattern as a comparison.
http://i143.photobucket.com/albums/r133/loki59/alum.jpg
This is closer to what I had originally envisioned, still leaves me with the soldered joint issue, but bedded in epoxy with a couple of coats of epoxy over all should hold it in place?

[pipefitter]

I epoxied in these copper drain tubes in the rear deck of my skiff. The glue surfaces were sanded coarsely before installation.
Another option would be a belt/suspenders approach and include clench points onto your pattern that could be driven in. This would keep the copper from shifting and also draw it up tighter upon clenching.

http://i99.photobucket.com/albums/l309/tigmaster/P5280011.jpg

http://i99.photobucket.com/albums/l309/tigmaster/P5300014.jpg

This wasn't West's. It was a sampler from Progressive Epoxy Polymers Inc. It was their 2/1 ratio mix IIRC. Nothing special, just sand well and cleaned with alcohol before installation. All is well with the install.

A guy that used to work at our shop used to TIG weld copper. He worked for a casket mfg. IIRC.

Here's a nice copper weld. If you know how to TIG, you're all set or find someone who does.

http://www.cryenco.com/images/photos/shop16.jpg

[ChrisBen]

Wow, that copper tig work is nice. Though I grew up in a sail loft, I went into the awning business, a little less seasonal. So, I started out with stick and later went to mig, I never tried tig. I've decided to go with the method in the above picture of the brass tube cut back to the red line and attach with brads probably bedded with epoxy after a good sanding of the interior surface with 60 grit.

[ChrisBen]

I used the brass tubing and roughed up the inside surface with the angle grinder prior to bending, to give the epoxy something to hold on to. It's holding pretty solidly but I used brass brads for insurance. Just put the fifth coat of varnish on this morning, 7 more to go.

http://i143.photobucket.com/albums/r133/loki59/paddle2-1.jpg
http://i143.photobucket.com/albums/r133/loki59/paddle1-1.jpg

[Mrleft8]

Poplar paddle? I don't think that poor (But beautiful) piece of brass stands a chance. Poplar has a nasty habit of warping quite radically when introduced to water...

[ChrisBen]

Yea, good eye Lefty. When I built the canoe I was just going to buy a double paddle. The only ones I found locally were aluminum shaft and plastic blades or carbon fiber and plastic blades, and I was looking for a wooden one. I knew I had some left over ash so I took the measurements of one in the store, and checked the scraps at home. The ash was only 6', I had enough white oak but thought it would be to heavy. The only other scraps long enough were some poplar left over from some cabinet bases I built. It lasted 15 years with no warping, so maybe I get lucky again.

[Mrleft8]

Maybe..... I bet the lumberyard has some nice Spruce that'd do real nicely for next to nothing....

[dpincus]

I gotta say this was one of the nicest threads... I need to stay out of the bilge. btw great job on the paddle.

[ssor]

I found a good source for .062" brass plate. The kick plates on doors go bad looking and get often changed.

Sorry I lied, the kick plates are .037 and the hand push plates are .052

[emichaels]

Chris that is a nice looking detail. Good job.

Eric

[ChrisBen]

ssor, why didn't I think of that myself? I worked in a doorshop part time during college.
Thanks dpincus/emichaels, a couple more coats of varnish to go and maybe I can hit the water this weekend if it warms up, down in the 30's the past couple of mornings.

[ChrisBen]

Finished up with the varnish on Saturday, hope to get on the water this week.
http://i143.photobucket.com/albums/r133/loki59/finis1.jpg
http://i143.photobucket.com/albums/r133/loki59/finis2.jpg