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PostPosted: Tue Dec 25, 2012 12:02 am 
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So I've been wanting to build a resonator. I still have tons and tons of research that needs to be done before I start. Hopefully I'll be able to figure it all out and get started within the next 6months or so. I know that many have a wood body and many have a brass body. Does anyone make an aluminum body? If not, how would it effect the sound? I'm guessing the body does not have much to do with the sound but I thought I'd get some good qualified responses on here.

If things go according to plan and the aluminum will work I may get to have a cool build coming up soon. :mrgreen:


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PostPosted: Wed Dec 26, 2012 12:51 pm 
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I've played one with an anodized aluminum body built by Louie teckonof. His shop was just down the road from national resophonic and he used a national cone and spider. Tone was very smooth, even with a slide. If I remember correctly it had a neck of Padouk. Louie was both a master metalworker with a business building show cars and a builder of many fine instruments.

-jd


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PostPosted: Wed Dec 26, 2012 1:00 pm 
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Thanks for the reply JD. My plan is to make a one piece cast aluminum body. And then just have a little machine work for the sound holes, neck joint and resonator well. Ive still got quite a bit of planning to do but Im thinking this may just work. Im glad to hear that you have played an aluminum body that sounded good.


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PostPosted: Thu Dec 27, 2012 12:34 pm 
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There is absolutely no reason not to use aluminum, but it would seem to make more sense to make a weldment rather than a casting (unless you have access to a really good mill to do the finish work. I happen to work in a very complete machine shop and one of my buddies is one of the very best titanium welders in the world (he worked for Moots cycles) - we discussed building a tricone out of titanium sheet but the cost got in the way (would that be a Ti-cone?).

Either cast or made from aluminum sheet, the aluminum is going to be considerably thicker than bell brass or steel - that may dampen or dull the sound - I really don't think aluminum will ring like a steel or brass resonator (I would be tempted to do some tests tapping different thickness of different aluminum alloys as well as steel and brass much like we tap billets of wood to see how they will sound in an acoustic). Some other things to think about - I relate this to what I know about different materials for bicycles (I race bikes) - both steel and titanium have a certain flexibility or "life" to the frames that aluminum framed bikes don't have. They are light weight but often very stiff - that tells me that your guitar might also be fairly lifeless.

For what it is worth, here is a guy that makes aluminum bodied guitars - they are not resonators in that they don't have a sound well and cone, but the do have a metallic reso sound.

http://www.eddowling.com/pages/Technophonic.shtml

I have had some dialog with him in the past - he might be willing to answer your questions.


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PostPosted: Thu Dec 27, 2012 1:28 pm 
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Thanks for the info freeman,

Im leaning toward casting because it just seems to make more sense to me. Why cut out all the peices and put them together when you could just make it all at once. My family has a non ferrous sand casting foundry so it kinda fits what I do already. I run the machine shop so i could make all my own tooling and do the machining fairly easily. Ive always wanted to make a cast aluminum electric guitar but I just recently got the idea for a resonator. I could definitely do some testing of thicknesses and various alloys to see what sort of sound i could get. Hopefully Ill have time to get this thing rolling

I know there are some parts we make that are a yoke that is over 1/2 thick made from heat treated aluminum alloy 356. if you knock the end of those parts together they ring like a tuning for with sustain for at least 1.5 minutes. so hopefully the resonator will ring too.


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PostPosted: Sat Dec 29, 2012 4:43 pm 
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I'm guessing the body does not have much to do with the sound but I thought I'd get some good qualified responses on here.

Not the case at all, the body material makes a huge difference. There are some good YouTube vids made by National R-P demonstrating the various cone configurations and body metals. I played a Progreba aluminum resonator and while it sounded good I prefer, steel, brass or German Silver ahead of it.

IMO, casting makes zero sense given the thickness of the panels and the surface that results from the casting process....but then I don't own a foundry. ;)


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PostPosted: Sat Dec 29, 2012 7:58 pm 
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Thanks for the thoughts mike. I could always cast it from brass (we do quite a bit of brass casting). But then you would need a crane to pick it up laughing6-hehe

I can actually get it fairly thin with casting. I just have to get all the risers in the right places. And I can get a fairly smooth finish too especially if I run it through the burnisher, if it'll fit. Hmmm I just don't know if it would be a worthwhile project or not...


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PostPosted: Mon Dec 31, 2012 11:43 am 
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ZekeM wrote:
Thanks for the thoughts mike. I could always cast it from brass (we do quite a bit of brass casting). But then you would need a crane to pick it up laughing6-hehe

I can actually get it fairly thin with casting. I just have to get all the risers in the right places. And I can get a fairly smooth finish too especially if I run it through the burnisher, if it'll fit. Hmmm I just don't know if it would be a worthwhile project or not...


My only other thought here is that according to my Beard plans, the usual thickness for steel or bell brass is 0.032". Depending on your alloy (and you robably have all the engineering referenece materials to do the exact calcs) the thickness of aluminum is often 50 or so percent more to qet the equivalent strength and stiffness (again, I am relating to bicyle frames). So that means that you will be working with wall thickness of maybe 0.050 - that seams pretty darn thin for a casting. I'll add that a normal steel or brass resonator is heavy to start with - with Al you'll be a little lighter but not much.

The other problem that I have with casting is that there are lots of little figity pieces that would have to be cast, machined and then fitted together (welded or screwed) In particular, the cone well and neck block. If you don't have them, get the Beard round neck reso plans - at least that will show you what you are getting into.

And, whatever you do, please take lots of pictures of the process and the final product.

edit to add, here is a recent thread about resonators that got posted in the normal guitar forum. It has several pictures of the insides of different resos (including a couple of mine) that will give you a little more idea of what is going on here.

viewtopic.php?f=10101&t=38641

I'll add that I work in a machine shop (not foundry) with lots of cnc mills and laser cutters, as well as solid modeling software to drive them. I've also built wooden resonators. All of this leads me to believe that you are getting into a fairly daunting project - Good luck


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PostPosted: Mon Dec 31, 2012 1:51 pm 
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Again thank you so much for the feedback.

.05 is very thin for a casting and when poured it would have to be thicker than that otherwise the metal would cool before filling the entire mold. But I think that being a little thicker would not be so bad plus I can run a cleanup cut across it when machining that would make it a little thinner. Maybe a finished wall thickness of .1 or .15 could be accomplish fairly easily. I've made parts of certain alloys that are much thicker and still have a bell like ring to them. In fact some of the brass tone rings for banjos can be around that range. As far as the small pieces like the resonator well and neck block the plan is to have all that cast into the part so it would need minimal machining afterwards. I would have to clean up the well for the cone to sit, drill and tap hole to attach the cover plate and cut a mortise into the top for the neck to attach. And maybe some quick cleanup passes to thin the walls and true the surface (at least on the face). By making a core I can get the details inside of th box at the time of casting. Also by leaving the saoundholes large like on a tricone and using covers I think it would keep the weight down.

If I proceed with this project I'll be sure to document everything. Lots of photos. I guess if just put a build thread in the resonator forum? Maybe it would help generate some more interest here :)

So what do you think so far with the plan? Any more thoughts or opinions are very much appreciated.


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PostPosted: Mon Dec 31, 2012 4:46 pm 
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I can actually get it fairly thin with casting. I just have to get all the risers in the right places. And I can get a fairly smooth finish too especially if I run it through the burnisher, if it'll fit....Maybe a finished wall thickness of .1 or .15 could be accomplish fairly easily.

Hmmm I just don't know if it would be a worthwhile project or not

These things are made with sheets of metal soldered -or welded in the case of aluminum- together. If you want to cast something maybe do a solid body resonator similar to what Fender did here. I just don't see a one-piece, 3.5" deep, hollow casting plus a cone well.

http://www.stratcollector.com/newsdesk/ ... 00262.html


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PostPosted: Tue Jan 01, 2013 10:34 am 
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I've never made a metal body.....but 0.15" sounds WAYYYY too thick to me. Maybe for a hybrid electric/acoustic. A chambered solidbody type guitar.
I do know something about castings and it seems like the wrong way to make the body. Very thin cross sections and a relatively large surfaces. You'd need a pressure die-cast to get any type of descent surface.
You probably have the tools to work sheet metal into shape already. Any reason you don't want to go that route?


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PostPosted: Tue Jan 01, 2013 11:14 am 
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Zeke - it sounds to me like you are determined to cast a body, and you are looking for someone to say "go for it". Guitars made of sheetmetal simply can't be replicated by diecast metals - you will essentially be making a thin-walled chambered solidbody. You might like it when it's all done, but it won't ever be mistaken for a true resonator guitar. Have fun.

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PostPosted: Tue Jan 01, 2013 3:08 pm 
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Looks like the consensus is that it will be too thick for a resonator body. [headinwall]

I just thought it would be an interesting way to go about it because I did not think that the body had much to do with the sound of a resonator. I was under the impression that the body was just a framework in which to hold the cone and other pieces together. I'm glad for learning the truth. Thanks to everyone and their thoughts. I think this idea is going into the scrap pile :)

I may make some tooling for an electric or electric acoustic one day. I have actually drawn up plans for that before. Ill just have to go more traditional with the resonator if I pursue it. Come to think of it I've got a sheet of stainless just lying around......but I sure hate working with that stuff.

Thanks again everyone!


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PostPosted: Mon Mar 04, 2013 4:04 pm 
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Here's an aluminum body biscuit-bridge resonator I made. (Shown with an aluminum body acoustic I also made.) The resonator uses 0.040" material for front, back & sides. I've actually got the body glued together using regular kerfing. I don't know that much about resonators, but I found that the having enough mass at the rim of the cone was important for forcing most of the string energy into the cone itself, rather than vibrating the whole body. I ended up adding a steel ring inside (about 1lb of mass) underneath the rim of the cone which really made it come alive. I also used a steel neck stick welded to the steel ring and which bolted directly into the embedded steel truss rod. This gives me continuous a steel spine going from the rim of the cone all the way up the neck. I've been trying to find someone who knows how to play a resonator (I'm hopeless) so I can post a recording.

With your casting idea, however, you should be able to add enough mass directly to the casting to avoid all the fooling around with chunks of steel.

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PostPosted: Wed Mar 06, 2013 10:13 am 
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That was kinda my idea Jeff. Though it seems a lot of people think its not such a good idea. I dunno. I got discouraged by the people who said it wouldn't be a good thing to cast it. I may try and revive it but for now I'm focused more on wood guitars rather than aluminum. Thanks for your support though. I've also thought of casting electrics. Both body and neck.


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PostPosted: Wed Mar 06, 2013 9:31 pm 
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My feeling with a resonator is that most of the tone comes from the cone - unlike a wood-top guitar, you aren't relying on the properties of the top (or sides or back) to give you a good impedance match with the strings or with the air. The body construction merely colors the tone. A thick-walled aluminum body will have a different sound from 0.032" steel or 0.032" brass, but I doubt anybody can say a priori that it will sound bad. I'd encourage you to go for it.


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PostPosted: Thu Mar 07, 2013 7:53 am 
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I may just have to go for it jeff. Your thinking is spot on with my thoughts on how a resonator works. In my mind I see that the stiffer the frame of the reso the more tone you coax out of the cone. Sort of the same thinking as some have with acoustic guitars. They want the sides stiff so that they get more response from the soundboard and lose less energy to the rest of the guitar.

The only issue I can see with casting is to polish the body back out which could take a while. I think it may be to large to fit in our burnishers. We've go a big one so it'll be close. I may have to start designing a pattern for this thing. It'll take longer to make the match plate and corebox than anything else.


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PostPosted: Thu Aug 08, 2013 7:15 pm 
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I think Aluminium can work. Ive had success with making aluminium tuning forks, also with conventional type soundboards. I think there are various types of aluminium and it can varies in hardness.
If you can do it I would harden it some how unless you can find a hard type.
Aluminium is interesting stuff and I think the term "you get what you pay for" truly applies.
I beleive the best Res cones are hard because of the machinining process which compresses the material making it harder.
something to think about-.02 good luck with it , its an intersting idea.

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PostPosted: Mon Oct 14, 2013 12:03 pm 
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Last weekend I saw a Tim Teal (can't find him on the internet) ukulele that was astounding. It had the most delicate and narrow pearl purfling and side binding, the most delicate vine pearl inlay up the neck, and weighed almost nothing - considerably less than the the usual uke.

But the most remarkable feature was that the back and sides were made of a solid piece of figured Koa. The maker used a CNC machine to "carve" the back and sides, and the back braces were left behind when cutting the bottom. The owner said that he saw pictures before the top went on, and the sides were as thin as the same piece would have been bent from solid stock.

So if you can precision mill and are confident in your casting consistency, why not mill it very thin? Maybe a wood top? Didn't Martin make a plastic guitar with an aluminum, wood braced top?

You never know til you tried it! Don't listen to the naysayers.

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PostPosted: Tue Oct 15, 2013 1:02 am 
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"But the most remarkable feature was that the back and sides were made of a solid piece of figured Koa. The maker used a CNC machine to "carve" the back and sides, and the back braces were left behind when cutting the bottom. The owner said that he saw pictures before the top went on, and the sides were as thin as the same piece would have been bent from solid stock."

Speaking as a 'naysayer', what a crime wasting all that koa for no reason. Not to mention ending up with both braces, back and and sides with a boatload of runout. I've seen plenty of electrics made like that, but can't imagine a good reason for making an acoustic instrument that way. Also can't imagine why it would weigh any less than a standard built uke given the same thicknesses in back and sides.


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PostPosted: Mon Jan 13, 2014 8:33 pm 
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Aluminum resonators and AL bodied forged and cast guitars have kept me busy for some time. My goal is to advance the systems and address things that I percieve as shortcomings of the "tired "dobro and national designs that (as wonderful as they are) are becoming "same old stuff, over and over again.
The evolved design shown features an "in house "spun 10.5" cone oriented base front (like an amp speaker) Topped w a triangular forged torsion plate(that acts like a "spider ") the bridge element is below the 'center 'of the cone(shortening the design overall, and perhaps allowing for leverage amplification of vibrational movement).This plate is connected via aluminum screw to a female threaded balsa/carbonfiber laminated "cookie "on the cone peak.The individual string seats are threaded aluminum rod stock w aluminum lock nuts (height adjustable). This is a wedge shaped forged body(@.035dimpled aluminum)arched top and, screwremovable arched back(to get under the hood).Tuners are positioned at the rear (handy, and shortens the overall design)Binding is blk/wht epoxy.Neck is 3pc 100year old oak.fingerboard is. 035 polished stainless steel (24 frets back pressed to a height of@.035 on a twenty ton press)The board wieght is less than a wood equivalent.Vibrato system is designed to be "flat-only incapable of sharping notes. The weight is around 5lbs",much less than an old national(the new nationals seem heavier than the vintage examples)Much like a wooden guitar the whole thing acts as a coupled resonator system, each surface contributing to the the sound.Neck is tilt adjustibl. Thanks for the great forum, Ben


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PostPosted: Mon Jan 13, 2014 10:50 pm 
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PostPosted: Sat Feb 28, 2015 11:07 pm 
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ZekeM wrote:
Thanks for the reply JD. My plan is to make a one piece cast aluminum body. And then just have a little machine work for the sound holes, neck joint and resonator well. Ive still got quite a bit of planning to do but Im thinking this may just work. Im glad to hear that you have played an aluminum body that sounded good.


Casting is tough and leaves a rough surface, which means a ton of finish work. I would suggest sheet goods, especially if you have access to an AC TIG (Tungsten Inert Gas) welder with high frequency output and some sort of throttle (foot peddle, or thumb throttle). Tig welding aluminum is tricky but can be done with a little practice. I've never built a guitar before, starting my first one now, but I've done lots of research on metal body guitars and german silver seems to be the most popular medium for the body. And all you have to do is braze it which is way easier, I learned to braze metals in five minutes in trade school where it took me a few days to learn to tig weld properly. Hope this helps, I've tried casting bronze before and it isn't as awesome as it looks on the internet.

Cheers.


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