Working Silicon Bronze

worked quite a bit with it in the ship yard using cnc routers......20 years ago. What exactly do you want to know.

Tips from the new england black smith http://www.newenglandblacksmiths.org/tips_&_tricks.htm

bwire,

It didn't render info for this project, that I could find, but great resources! I have ordered a couple of books from there. Thanks!

You can cold bend the bronze it depends on how much of bend you need as it will work harden whilst bending ,if you over bend it will be difficult to correct the work hardened area.Then you will have you anneal the bronze by heating to just below a red heat and let it air cool so you can rework the bend. It is possible to bend whilst hot then cool rapidly with water this will bring the tensile back again. One problem with bending whilst hot is if you go over the short heat of the metal it will crack. So if your bends are not excessive I would bend cold and leave as is. If you are using a jig once you have allowed for spring back your bends should be consistent and match each other, it is getting the first one correct that is the tedious part.

Ed,

Good stuff as well! I absolutely do approach this from the exotic wood stand point except that this stuff is way more expensive than any wood that I have come across!

Joint design is what I am all about. These will all be machined to +/-.010". I am a stickler for tight joints.

I had not considered brazing as opposed to welding though. Any suggestions on alloy for filler? I have always welded this stuff and had great luck putting it together but I do notice that the weld zone, the filler is slightly lighter in color and I can usually work that with the patina but it has always bothered me. I could see brazing. Talk to me!

I look forward to all of your comments!!!

Shea

Alright, this is what I'm looking for...

I was thinking of having the bars , that I have to bend, annealed before trying to bend them. If I do that, will I have any spring back? How soft can I get this material? Once it is bent, fabbed and installed, the stone that it's bolted to ought to offer the strength needed to hold this door up. I don't need this thing to have loads of tensile, as suggested with the water cool down. I just need it to hold its shape while I gingerly install this thing. I will template the opening and then draw in acad specifically what I need for the door. Do you have any technical info on heating to anneal, i.e. temps, cool down schedule and what hardness/softness that will render? What is the 'short heat' of the metal?

I was thinking anneal the bars that get the bend and have a jig laser cut for the inside and outside and then press into shape. Will that hold its' shape when it comes out of the jig or have springback?

I believe the fracturability in the material is rather high. did some rudder shaft on boats, not a good experience.

I am assuming that the bends of your flat bar are a gradual curve type to suite the arch? I would not recommend 90 degree bends so definatley use annealed bronze a good supplier should be able to provide this. There will always be some spring back you will have to over bend to compensate for this and the jig will need to be altered until you reach the correct curvature to give you the result you want with one action. Like I said before the first one is a B. Don"t forget it work hardens every time it is bent. Brazing [weld]the metal is quite easy, try Eutectic Company for low teperature color matching welding rods. Silver solder is OK if you can get a silver content low enough to match your bronze color, 50% is good but will show up silvery unless you have perfect joints and can clean the surface off. But you will probably be welding on the backside of the frame at a guess?? Some information for you:- Hot shortness is the temperature at which the metal will crumble. Silicon BronzesPrincipal Type Silicon Bronze (A, B), Silicon Aluminum, Bronze Principal Use Hydraulic tubing, marine hardware, chemical equipment Recommended Brazing Filler Metals* Cadmium Free Alloys: Braze 600 and 505 Cadmium Alloys: Easy-Flo, Easy-Flo 3 Easy-Flo 35 and Easy-Flo 45 Recommended Fluxes** Handy Flux or Handy Flux Type LT or Handy Flux Type A-1 Recommended Atmospheres Type - Maximum Dew Point Purified, Lean Exogas - -40°F/-40°C, Dissociated Ammonia - -40°F/-40°C, Vacuum Remarks In furnace brazing, flux may be used with the atmosphere for good "wetting" by the brazing alloy. Silicon bronzes must be stress relieved before brazing to avoid intergranular cracking and must be brazed below 1400 F (760 C) to avoid hot shortness. Use Handy Flux Type A-1 with silicon bronzes containing aluminum. Hope that helps.

garth -- good answer. You're way ahead of me on this one.

I spent an hour last night with my reference books before I got sleepy. I pretty much found the same info you have presented. But you did a great job of reducing it to writing.

I would add one point about the atmospheres. Those recommendations are for furnace brazing where you can get a controlled atmosphere. I seriously doubt if that is an option in STOLISMA's case. Likely he will be torch brazing and the best he'll be able to do is maintain a good reducing flame.

I think his biggest problem will arise if he has problems with overstressing and cracking the material while it is in the "hot short" heat range. This could come from how the assembly is heated in the brazing process. The other point here would be that if the assembly is to be precisely fixtured for brazing it would be best to have any rigid locators on the inner side of the "ring" and locators on the outside somewhat flexible to allow unstressed thermal expansion.

One other thing I'd suggest is that he take advantage of any factory application engineering expertise he can tap relative to selection of the brazing alloy. Since he's a professional such help might be forthcoming with a nudge from his welding materials supplier. I did pick up one bit from my reading last night. That is that these brazing alloys vary a lot in their ability to properly fill gaps in the brazed joint as well as their temperature range. So some realistic appraisal of the spaces the braze metal has to fill in the final setup is appropriate.

I'd recommend some practice and experimentation with small quantities of several selections of filler metal be done before the main event.

This morning I found a chart on the CDA website (links below) showing the constituents of Alloy 655. Don't see any aluminum there; but lots of silicon to aggravate the hot shortness issue.

http://www.copper.org/alloypdf/alloy170.pdf

http://www.copper.org/resources/properties/db/SDResultServlet.jsp?Action=search&service=COPPERINTRA&ACtype=Wrought&Alloy=Bronzes&term=Copper-Silicon%20Alloys%20%28Silicon%20Bronzes%20and%20Silicon%20Brasses%29&alloyStart=C64700&alloyEnd=C66199

Ed Weldon

Garth...

Second picture, elevation, tightest radius is 8.5" and then a very gradual radius to the peak, machined joint at the peak. First picture is cross section of jamb put together out of what I am finding available. 1/2"x2" is the largest flat that I am finding in either cold drawn or extruded. I am seeing these bars being annealed, pressed into form that I will cut to match the opening and then tig welded in the jig, that should leave me with very minor, if any, adjustment when it comes out of the jig. The two halves (left and right) would be bolted to the stone arch on site fitting the top joint by hand on site, no weld/braze.

Sorry for the picture quality. I had to upload to fb from my phone, save to desktop and load from there but that gives you the idea.

Next issue, there is no availability for the 3/4"x1" bar for these mullions (mullion in yellow with four corners milled to 3/16" radius, 3/8" round solid in blue). The closest that I can get there is plate that would be sawn or waterjetted. Neither of which are really what I want for straight/flatness for milling. I can however get 360 brass in that size that would mill nicely and be straight. The through hole for the 3/8 solid is reamed to snug fit. What would I run into brazing the 360 to the 655? All of the 360 would have to be brazed, no welding. I will likely run continuously, vertically and joint the horizontal intersections.

There is obviously more to this story but that hits most of my concern at this point. I will look up Eutectics Company in the mean time and thanks guys for being here!

My name is Shea, by the way. My company is STOLISMA.

Shea -- 360 will weather stain a lot faster than the 655. It may look nice when delivered; but I don't think your customer will be happy for very long. Polish 360 and in days the first fingerprints will begin to show.

Are you planning to groove the mullions to hold glass or some other kind of panel? If so, then a two piece design fully machined and furnace brazed together into one piece may make sense. Doing it all in one lot may justify the startup/setup cost of the large furnace. I'd search out a pro shop for that one.

BTW, have you looked for 1" round bar in 655 or a closely related copper alloy? As long as it's going to go on a machine to get the desired radii on the corners you could easily mill round into a rectangular shape.

Ed Weldon

Ed,

No groove for any panels. It is just the mullion grid and then 3/8" round dividing that grid.

This is an interior door, air conditioned full time. I am pretty sure that I can come very close on the patina between the two. I will probably blast with glass bead and patina, fairly dark, from there. After patina, I would heat it up and wax the entire piece with several coats of wax. I have had pretty good luck with that finish over the years and the folks that are spending this kind of dough typically have a house keeper that can wax it twice a year or at least a coat of pledge bi monthly.

Honestly, I am a little out of the comfort zone doing the furnace braze, having not done that before. Finding someone here that will take the time to work with me and the care to get it right, well, you know where I'm going with that.

Shea

Shea -- The furnace braze suggestion was kind of a long shot. Yours is the kind of job that has to capture the imagination of the business owner. Your town is the nearest thing to a true industrial city in your part of the world. So if you don't have a promising resource there you're kind of stuck with squeezing what you need into an envelope or a wire and hoping they can read it on the other end. Doesn't work well on new jobs that are small and fussy.

On the other hand I think there is hope if you can find the 1" 655 round bar and someone with an old Cincinnati horizontal mill.

Ed Weldon

Good idea machine the flats on the round bar easy way to go. Am not sure what part of your assembled project is hidden but Tig welding is a good way to go. You can use a piece of the original flat bar as a filler metal [ cut down to a usable size ] if you need a good color match. If you set the whole thing up in a jig with a peg board lay out it can be assembled with the horizontals and verticals laid into there respective holes, you will only need to Tig weld the exposed ends, you wont even need any filler metal. Regarding the 3/8" rounds through the 1" sections you do not need to braze them all for a ridged structure. In any case there is a method of hidden brazing where a grove is machined into the 3/8" round where it resides in the center of the 1"section, when you assemble the whole thing fit a ring of the silver solder wire in this groove and pre flux it. When you have done all the Tig welding heat up the appropriate joints, I doubt you will even see any solder come out if done properly. Experiment on some test pieces first as you wont be able to undo what is done. Sorry about the lay out of my writing! Opera does not like paragraphs.

Another GA, garth. (I laughed at your last sentence)

The first piece of the 1 x 3/4 from a 1" bar can be slabbed off by hand feeding it through a band saw at about 200 fpm and then cut in half the same way.

If you have a 6" cutoff saw take a 6" long piece of any of your silicon bronze flat stock, clamp it to the outfeed surface with a big Kant-twist clamp and slice off thin layers. Then make a little clamp handle to hold them while feeding into the weld zone.

Ed Weldon

(p) with square brackets [ ] for line breaks on Opera, chrome or safari

This is definitely one of the small fussy projects, as most of mine are. There are two furnaces in town that I know that 'have' the capability, but I don't know that they are 'capable' and it would be my reputation on the line, not to mention $6k worth of bronze.

This is the sample that I put in the architects' hand and said, 'is this what you are looking for?' I had the job the next day when they met with the client. The details are what sell the job and that's why I am here asking questions. I have one shot at getting this right and have more confidence in my ability than anyone else here in town. However, I'll be the first to tell anyone that I don't know it all!

I am going to try several test joints with silver solder and see how that goes. That was the kind of input that I was looking for. Soldering/brazing had not even occurred to me as I have always welded SB when I have worked it in the past.

The backside of the jamb where the bars are stacked to form the jamb, will be hidden so after pressing this into the jig, I can weld the backside. Joints to be decided.

Let's look a little deeper into the annealing.... When I spoke to the guy at the furnace shop about annealing the bars for me, he was cluesless on heats and times schedule for bronze. Where can I read up on that?

Shea

p.s. I couldn't squeese a 3/4"x1" bar out of a 1" round, lost some corner...

Shea - I have a couple of ASM handbooks (8th and 9th editions) on Heat Treating. I don't have time this afternoon to dig through them to see if there is immediatly applicable info there but I will tonight and let you know.

I realize the espense, but is a bar stock size greater than 1" available? There is a rare but important application for this material in the restoration of old large wooden boats for fastening keels. Lots of money can be spent on such projects. Some digging in that subculture might illuminate sources. Search in the Wooden Boat world. An inquiry to the publisher of the magazine of that name (a relatively small business in Maine) migh turn up leads to sources of material.

Ed Weldon

Shea and others -- Here's more information.

The ASM Metals Handbooks are pretty thin on info relating to annealing CDA 655 Silicon Bronze. But they do list the annealing range as 900F to 1300F. The general discussion of annealing bronzes and brasses suggests that the higher the temperature the more the grain growth making for easier forming at the expense of achievable surface finish for polishing. Probably not a problem for what you are doing.

This company has 1" square CDA665 bar in 12' lengths

Atlas Metal Sales, 1401 Umatilla St.

Denver, Colorado USA 80204

Telephone 800.662.0143

kloughrey@atlasmetal.com

http://www.atlasmetal.com/pdf/catalog.pdf

http://www.atlasmetal.com/silicon-bronze.php

http://www.atlasmetal.com/silicon-bronze-square-rod.php

http://www.atlasmetal.com/contact.php

There is another Atlas Bronze Co. in Trenton, NJ. Different company.

Also here's a web page that has some good practical info in it:

http://www.newenglandblacksmiths.org/tips_&_tricks.htm

Shea -- Check your email for one from me giving the relevant text from the New England Blacksmiths link.

Ed Weldon

Ed,

good tip on searching the nautical realm, it had not occurred to me.

Also, so glad you searched atlas. I have quoted with Atlas, Farmers, National Bronze and Alaskan Copper. Atlas had the best selection, if not price. I was asking for 3/4x1 which they did not stock but yes, they do have the 1x1. Again, thank you!

On the annealing, the 900-1300F range is what I am finding but am looking for something a little more in depth. That's a pretty wide range and leaves out the time factor from what I have read. I know that these variances will effect my end workability and don't want to be shooting in the dark. I am not looking to polish but surface finish is important to me.

Side note... I just ran across an old heavy machine shop that needs to be liquidated. I know some good avenues for selling the smaller manageable machinery but there are two machines in there that are outside my experience. One horizontal boring mill and one vertical boring mill. Both of these machines are roughly 15' tall and I couldn't even begin to guess what they weigh. Any tips on marketing these beasts? Surplus Record is where I will start but just asking around at this point.

Shea

Sir,

What are the practical usages of Silicon Bronze? Whether there are any additions to the Alloy besides 3-4% Silicon to give Golden Looks? Are we using Silicon Bronze in general engineering, particularly mechanical?

Thanks & Regards; waiting for your answer_ _A_N_Harshe

Silicon bronze has limited use in general mechanical engineeriing. The most noteworthy application of silicon bronze is where its combination of corrosion resistance to sea water, high mechanical properties, machinability, formability weldability and moderate cost make it ideal for certain long life marine applications. This is particularly true for wooden boats of all sizes in the current times.

One might ask what makes wooden boats ideal applications for this material where in times past it was primarily used in the high end high quality boat construction. The reason is that wooden boats are still primarily high end boat examples primarily due to the fact that in spite of the quality and performance ability of competing materials like composites wood has an aesthetic quality that is highly prized. And note there is a certain tradition in the use of bronze fitments in wooden boat construction.

So why don't stainless steels supplant silicon bronze in these salt water applications? Indeed many boat fittings remain out of sight in the final construction. The reason here is the common 316 stainless steel does not match silicon bronze in terms of corrosion resistance to sea water. One must advance to the higher nickel stainless steels like alloy 20 or even the nickel alloys in the Hastelloy family for the worst sea water corrosion conditions (such as waterline exposures). At this point not only the high material cost of the nickel alloy but also increasing fabrication costs and outright barriers to some fabrication methods begin to outweigh the disadvantages of silicon bronze.

When one considers high end architectural hardware the combination of aesthetics and tradition of a bronze fitment as well as the durability of the material such construction becomes highly desirable.

With respect to appearance of the silicon bronze alloy one must consider not only the appearance of the new part but also the appearance of the part as it ages. It gains a certain patina, largely as a result of exposure to atmospheric conditions but also exposure to human usage, that is indicative of its nature and quality. Other bronzes may not age the same way and some brass alloys will actually develop a corrosion bloom of different colors in spite of their similarity to the bronze when new. This becomes an indicator of the actual quality of the work and a devaluing factor.

Ed Weldon

Ed,

Thanks for the talk. it spurred plenty... Garth, thanks to you as well for your input.

I am definitely going SB655 because of my comfort welding over brazing.

(I'll take improved reputation over a little more profit any day, 655 vs. 360)!

I will let you know how the pull trials go with the fish scale after annealing.

I'll also post pics throughout so that you guys can see what you have helped me with!

Thanks, Shea

Hi Shea,

As a foot note re silver soldering there is a grade used for copper to copper joints which requires no flux. Check with plumbers supples. This will possibly work with bronze in a hidden joint, I have not tried this myself, but it will remove the problem of flux leakage and discoloration later.

Cheers Garth.

Alright Ed, not only did I have a healthy respect for your metallurgical knowledge but now I think I have a man crush... Incredible defense of a beautiful material.

I'm trying to post pictures of the project in process but the site locks up on me. I will keep trying. I have not gotten to bending the jamb bars yet but have had them annealed and that is coming soon. I am thinking that I will have to bend them hot in low light...

Shea

Also poured handles for the door last week. Hadn't poured in years. I have to start that again, too much fun. By the way, did I mention that this is a child gate? This is to keep the kids out of the basement!This room is in the basement.

Glad to see your making progress. It looks like a long drawn out job with no expense spared? Keep the info coming am interested in your problems and resultant solving of same.

WELL, HERE IT IS. A LITTLE OVER -MY- BUDGET BUT WELL WORTH IT!

THANKS TO YOU ALL FOR THE AWESOME INPUT AND INFO.

NO REAL PROBLEMS IN THE PROCESS OTHER THAN TIME OF COURSE, IT IS STILL FOR PROFIT. THE MACHINING WAS TEDIOUS AND MOST ENJOYABLE. I WAS WORKING WITH QUALITY HARDWARE BY SUN VALLEY BRONZE AND ACCURATE MORTISE LOCK AND BALDWIN CYLINDERS.

THE BENDING OF THE JAMB WAS THE MOST NERVE RACKING BUT OF COURSE DID AS IT SHOULD IN THE PROCESS. BRONZE IS LIKE BUTTER AND IS A PLEASURE TO WORK. I SPENT TWO DAYS WITH MOST OF THE LIGHTS OUT AND FOUND THE IDEAL COLOR AT WHICH TO FINESSE THE MATERIAL AROUND THE JIG. I DID NOT REALLY DO ANY CONTROL TESTING (SORRY GARTH) UP FRONT, I'M MORE OF A SEAT OF THE PANTS TYPE. ONE REGRET WAS NOT DOING THE POSITIVE/NEGATIVE STEEL JIG FOR THE TOP CURVES AS I HAD CONTEMPLATED BUT OPTING TO BEND THEM BY HAND. I HAVE LEARNED THAT ON OTHER PROJECTS IN THE PAST BUT SOMEHOW ALWAYS END UP DOING IT THE HARD WAY. THOUGH THE OUTCOME WAS SWEET, BENDING TWO HALF BY TWO BARS WELDED TOGETHER INTO A HALF BY FOUR WAS STOUT AND I WAS WORKING BY MY LONESOME. I DID HAVE THE BARS ANNEALED PRIOR TO STARTING BUT IN HIND SIGHT, THAT WAS $100 OUT THE WINDOW.

THE INSTALLATION WAS PRETTY SMOOTH OVER THREE DAYS. FIRST DAY DRILLING AND SETTING THREADED INSERTS, LET THE EPOXY CURE FOR 24 HOURS. DAY TWO WAS HANGING, TUNING AND FUTZIN AND DAY THREE WAS PAINT TOUCH UP AND PLENTY OF PRAISE FROM ALL THAT WERE THERE TO WITNESS. I STILL HAVE A HARD TIME WITH THAT PART.

IF ALL GOES WELL, I WILL BE DOING MORE RESTORATION WORK ON THIS HOUSE.

http://www.bhamwiki.com/wiki/index.php?title=Theodore_Swann_residence

THIS HOUSE IS LOADED WITH INTRICATE AND INGENIOUSLY DESIGNED WORKINGS THAT I WILL DEFINITELY BRING TO YOU ALL WHEN THEY COME UP. AGAIN, THANKS FOR ALL THE HELP!

SHEA SCULLY

STOLISMA INC.