uncle.fogey - Posted - 02/06/2011:  07:25:55

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I had to make brackets, hooks, and nuts, a bracket band, tension hoop - the whole nine yards, for a special project I'm working on (I will NEVER do this again).


I'm putting a dark patina on them for an "earthy" effect.

Here's the problem:
Some of the hooks are breaking at the bend when I torque them down. I think this is from work hardening from bending the brass in a tight bend. I can silver solder them back together and that seems to be stronger than the original.

I want to make some back-up hooks but This time I want to anneal them so they don't break.

Should I anneal the metal before I make the bend?
Should I anneal it again after bending?

I'm getting some mixed info about annealing brass; I always thought you should quench it - just the opposite of ferrous metals.

Who out there knows the best way to do this?

Thanks

rudy - Posted - 02/06/2011:  07:46:46

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Uncle,
Bill Rickard posed a question regarding this problem a while back. Since he has started to offer brass j hooks for sale you might want to message him and see what his solution was. I'd like to know, too. I most likely won't start using raw brass hooks any time soon for a number of reasons, but it would be good to tuck into the old archive machine for later referance. Here's the old topic:

banjohangout.org/topic/186511

Tom Rice - Posted - 02/06/2011:  07:47:41

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Before you bend the brass, anneal it. Brass is annealed the opposite of iron. Heat it to a good red approching orange then quench. Depending on the brass it should be dead soft. If not heat it to orange, then quench. If your working it with lots of bending it will work harden, just anneal it again. Hopefully your working with a good yellow brass rod, as opposed to paler or whiter brass which is becoming more prevalent in these times.

uncle.fogey - Posted - 02/06/2011:  08:54:08

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Thanks guys. I have to order more 5/32"Ø rod. I think the reason that my silver solder repaired ones don't break is because I heat the end of them to cherry red in order to make the repair, and then quench them, so I'm annealing them when I do that.

Out of 24 hooks, I've probably broken 12.

Tom, I really don't have any choice as to alloy with 5/32". I have to get regular free machining brass. Do you have a good supplier of better stuff?

Dogfeathers - Posted - 02/06/2011:  11:06:28

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Uncle Fogey,
You did not mention which brass you are using which may be the key to being able to bend it sharply without it fracturing when bending or fracturing under load.
I get a lot of materials through McMaster Carr and here is the link to their choices of brass rod offered.
mcmaster.com/#brass-alloys/=ax20lo

If you are choosing the free machining brass (360) for the threading operation than it may be too hard and give you the fracturing problem. Try 260, it is more form-able and it may work better for you. 5 /32 is offered in 5 each of one foot lengths item # 8859k54 for $13.59, or item 8859k168, 5 each of 3 foot lengths at $14.08.

Happy Frails,
Dogfeathers
SF Bay Area

vtyankee5 - Posted - 02/06/2011:  11:25:51

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I heard Tom Mirisola @ AMB Co eliminated the brass hook breaking at the bend problem. He's casting the hooks. The last I talked with him he was having great success with them.

blm10jn - Posted - 02/06/2011:  12:09:24

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Copper alloys work harden. This includes the brasses, bronzes, german silver etc. Annealing is done after the metal is bent. Copper alloys generally come in 3 grades of hardness, dead soft, half hard and hard. You should know which degree of hardness you have before you start working it (that includes bending and threading). Overworking can lead to metal failure under stress. Case in point, the hooks fail under stress and break along cracks formed from over working. The trick is either to anneal at different stages of bending to keep the cracks from forming or to bend hot. I think I would bend hot. One shot bend in a hot soft stage and cracks cannot form.

uncle.fogey - Posted - 02/06/2011:  14:28:54

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What I have been using is "360" brass alloy, which I believe is a free-machining alloy.
I first encountered this problem about 40 years ago with a 1928 Gibson Granada, where the hooks were breaking at the bend due to work hardening. I replaced the broken ones with gold-plated steel and thought no more about it ...until NOW.

I have backed myself into a corner with this "all hand-made banjo", because it's a juried art show entry, and I didn't want to have a lot of "store-bought" parts on my entry, so I made all the parts myself. Big mistake. The whole thing looks really cool


As an industrial designer, I appreciate the idea of casting the hooks, which is a "conceptual art" way to achieve a certain thing, and as a craftsman, I appreciate all the complex annealing strategies - as I said before, I will never do this again.

If someone who manufactured banjos was hiring me (as an industrial designer) to design hooks that could be "patinaed - Patined??)" to a dark brassy color and have the highlights buffed up, I'd specify steel hooks with a brass or copper plating which would react to the patina bath. I wonder if steel cleaned in copper pickle would accept the patina (?)

Question? Are these dark patina banjos going to become more popular? I like the way mine looks

rudy - Posted - 02/06/2011:  15:03:50

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I love the dark patina-finished raw brass look. It does shine up where there is wear from arm-finger contact, but in a really attractive way.
Your pot looks great! I don't find making the tension band or shoes too difficult, but I'm using commercially available steel hooks and machined nuts. I like the contrast between the patinated raw brass and the nickel-plated hooks and nuts. I have not used brass hooks, but I'm thinking that the formed steel hooks must be a lot stronger to begin with.

TR Dockery - Posted - 02/06/2011:  18:05:37

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Hey Uncle Fogey--

I bought some brass hooks made by Jimmy Cox to preserve the originals in a '29 Granada. Somebody suggested--and I did--use steel hooks to assemble the pot. Then, I replaced the steel hooks, one at a time, with brass. I reversed this to change the head once. A little more trouble perhaps but I haven't broken a hook yet.

Regards,
Randy in Germantown, TN

mike gregory - Posted - 02/07/2011:  09:36:11

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Good Lorne, but that's a fine looking pot!

beegee - Posted - 02/07/2011:  11:39:37

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Tom Mirasola sent me a couple of cast-brass hooks. I replaced my Granada's brass hooks with stell years ago. I will probably buy a set of his brass hooks.

Booger McGee - Posted - 02/07/2011:  14:04:40

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quote:

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Originally posted by uncle.fogey






Question? Are these dark patina banjos going to become more popular? I like the way mine looks

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That is a beautiful pot and the hardware really complements it. It seems like antiquing (brass and nickel) seems to be a popular option right now. While I like the look of antiqued brass, I like the idea of owning and playing an instrument long enough for it to build up its own patina better.

Booger

Kenneth Logsdon - Posted - 02/08/2011:  06:55:36

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Rule of thumb when stressing metal... Work it hot, form(speed depends on temperature of the metal, for less stress).... then reheat and treat to the hardness required or desired as the final step... the color is your control... Those in the picture look authentic, so your doing well except you don't mention reheating...With the right treatment/base material I don't see any reason that they should be breaking..

(I always peen with a hammer to let stress out before final treatment, but you would have to be very careful not to mark)

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Edited by - Kenneth Logsdon on 02/08/2011 07:01:53

uncle.fogey - Posted - 02/08/2011:  08:00:07

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Thanks, Kenneth,
So you're saying I should heat the end that will be bent, bend it, then after it's been trimmed and cleaned up, heat it again to cherry red, tap it with a hammer then quench it. Is that the correct procedure?

I was thinking that putting a drop of silver solder in the crease of the bend and letting it flow before quenching it might be a strengthening element. The cracked and broken one I repaired with silver solder seem to be stronger than the other ones.

I am using a 15% silver brazing rod for the silver soldering.

uncle.fogey - Posted - 02/08/2011:  08:02:00

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Another possibility is to get readily available gold-plated steel hooks and patina them. Can that be done, or is gold impossible to darken?

Jonnycake White - Posted - 02/08/2011:  09:16:11

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Gold doesn't really tarnish (patina), that's one of the reasons it's so valuable. For probably 20 years, I was unable to get my gold wedding band off my finger (until I got it cut off and resized recently), and through all of that working on cars, remodeling my house, painting, building banjos and other things, real abuse, it never tarnished (though it did get scratched up plenty). When they cut it off, the inside was as bright as the day I first put it on.

I've made a few hooks from brass, don't know what alloy, but the kind that is available at hardware stores. I anneal them two or three times as I do the bending and they've worked fine. I figured that out after breaking two or three of them by bending them cold. In my limited experience, it doesn't seem to matter whether you quench the heated brass or just let it cool naturally, just as long as it gets plenty hot. Quenching is more convenient. I also annealed them after they were bent.

Kenneth Logsdon - Posted - 02/08/2011:  10:52:47

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Ken... use some scrap/practice pieces and work on a technique of bending as you heat.... you can feel as it comes to the right temp as it will start to give and almost bend itself... so you will begin to reconize/develope a "feel" for it... As you practice, keep a watch on the metal, very easy to overheat and "burn out" and of course the opposite "too cold".. You can see the interaction?stretching(?) as the bend begins and continues..
just takes a little experience to develope the knowhow .. Because of the narrow heat range for brass, it would be nearly impossible to consistently get the same results by heating and then bending..Again temp and watching the color come up as you quench is your guideline, you can't just dump it into cold water. it has to be controled...

Learning tempering/annealing/quenching is about the same... just work with different temps and methods until you get the one that holds for you...
Its pretty well standard metalogy practices from the old school of Blacksmithing and metal working...

Just don't get into tempering cold chisels.. there are three or more tempers in one piece, and book after book has been written, simular to setting up a banjo!!!!!!!!!

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Edited by - Kenneth Logsdon on 02/08/2011 11:00:40

Kenneth Logsdon - Posted - 02/08/2011:  13:31:08

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----just realized your question about the tapping.... After its cool the from the initial bend...Not while its hot.. (Its and old habit of mine, just a couple light pecks should do wonders, careful not to flatten or leave marks where it isn't desired...)

uncle.fogey - Posted - 02/08/2011:  14:16:52

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quote:

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Originally posted by Kenneth Logsdon

----just realized your question about the tapping.... After its cool the from the initial bend...Not while its hot.. (Its and old habit of mine, just a couple light pecks should do wonders, careful not to flatten or leave marks where it isn't desired...)

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Thank you very much! I will do that from now on - it makes sense. Actually, if I have put a little flow of silver solder in the notch to consolidate it, a little tap on the side can't hurt. Once the hook is in place, all you see is the top of the arc and the back.

Ken

uncle.fogey - Posted - 02/08/2011:  14:21:51

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THANKS!
I would like to say thanks to everybody who contributed to this string. I got a tremendous amount of thoughtful response to my question, and I know how to proceed. It's the hangout at its best.

Thanks again.
Ken

Will1717 - Posted - 02/08/2011:  14:50:27

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uncle.fogey
Sounds like a familiar problem. If you can give me a couple of days I may have a solution. We just received a batch of brass hooks that have been professional annelled after bending. The problem may be that after the annelling process the brass may become more brittle than the original. In the next hour I'll test some and report back. I've also contacted a supplier that can do brass barrel plating which may be a solution also. Finding a brass barrel plater is like finding hens teeth as the new green movement has just about put these companies all out of business. We've also looked at every other grade of brass and 360 is the only good choice. Another problem may be your bending processs. I'll get back shortly with my findings.

Bill Rickard

Will1717 - Posted - 02/08/2011:  14:59:24

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uncle.fogey

Are your hooks breaking when you bend them or when you tension them up?

Bill Rickard

uncle.fogey - Posted - 02/08/2011:  15:03:07

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Thanks Bill!! I was hoping to hear from you.

You have more practical experience with this than anyone else. What do you think about brass or copper plated steel hooks? Take the patina, don't break.

Ken

GSCarson - Posted - 02/08/2011:  19:23:47

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Uncle Foggy, First off, great looking banjo! One other solution you could try is to make (or strip) some steel hooks and brown them with antiquing solution intended for Kentucky rifle builders. Produces a nice brown color and looks good with antiqued brass nuts. Looking forward to seeing what you end up with and also what Bill learns.
Glenn C.

uncle.fogey - Posted - 02/10/2011:  15:46:04

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quote:

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Originally posted by Will1717

uncle.fogey

Are your hooks breaking when you bend them or when you tension them up?

Bill Rickard

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When I tension them up.

uncle.fogey - Posted - 02/10/2011:  15:53:11

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I finally found a solution to the problem which seems to work (thanks to the advice that's been posted here):

(1) I file the inside of the hook where it bends with a needle file, just to clean it

(2) I put a dab of flux in there with a brush

(3) I stand them upside down, leaning against a firebrick, heat the end up and put a touch of silver solder in there, I heat it just enough to make the silver solder flow, which would be about 1250 degrees F

(4) when the solder flows, I take off the heat, lay the hook down with pliers, and tap it with the pliers, then quench it.

This seems to do the trick. Knock on wood, none of them have broken and I have torqued them beyond what was breaking them before.

uncle.fogey - Posted - 02/10/2011:  15:59:17

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quote:

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Originally posted by GSCarson

Uncle Foggy, First off, great looking banjo! One other solution you could try is to make (or strip) some steel hooks and brown them with antiquing solution intended for Kentucky rifle builders. Produces a nice brown color and looks good with antiqued brass nuts. Looking forward to seeing what you end up with and also what Bill learns.
Glenn C.

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Thanks Glenn,
For this banjo, which I will be posting soon, I needed darkened pegs. Using that JAX iron and nickel blackener you are talking about, I was able to darken a set of nickel plated pegs - they came out pretty good. I made the buttons from Corian scraps.