spinning cones

[Tim Toberer]

It took quite a bit of trial and error, but I am spinning acceptable cones. I had no luck spinning the traditional way, spinning over a form. I found a few videos of people spinning this way, into a form. It is pretty simple once you get setup right. The forms are made of birch scraps I had from a butcher block counter. Maple would be better. The aluminum must be near pure aluminum and annealed. About .012 thick for biscuit and tricones. I think spider cones are thicker maybe .020 or so, not sure. Spider cones are cheap and available. Probably won't mess with that. I use an oil wax mix for lubrication, with maple forming tools. I try to use even pressure and speed. Not too fast on the rpms maybe about 500 to 700.

[Chris Clem]

I like it. Always seemed like a relativly simple job to turn cones and experiment with different designs. I have an old 1930s Atlas/Sears lathe that I want to restore, I just don't have all that much use for it. But I could mount it an old stereo console l have in the shop, just the right height and shape to do the job.

It's a bit of messy job restoring machines but I have done it before, and a wood lathe is not all that complicated.

[Tim Toberer]

Always seemed like a relativly simple job to turn cones and experiment with different designs.

I would say deceptively simple. You need the right aluminum, and it needs to be dead soft. If you run it too fast the aluminum work hardens. Internal spinning is way easier. I spent a couple weeks trying classic metal spinning and it is dangerous and frustrating. The trick is getting an even thickness

[Erv Niehaus]

How many of these cones do you plan on making?

[Tim Toberer]

How many of these cones do you plan on making?

As with most of the things I do, there is no plan. I just make it up as I go along. I suppose I will make as many as I need. Right now I need 3, but I will make some more to see if they sound different. The great thing is, now I know I can make them if I need them.

[Erv Niehaus]

Maybe you should go in the business.

[Max Lee]

Very cool, Tim. Thanks for sharing your experiments and lessons learned!

Something about having a spinning razors edge moving at 150fpm has scared me off of attempting something similar but I like your method of securing the free edge!

I wonder if a degree of work hardening in the formed reso cone might be desirable from a rigidity or tonal standpoint? Or, conversely, if a post-spinning annealing step could improve the acoustic properties.

In the same vein, I know brass drum cymbals are often hammered after forming which appreciably affects the natural resonant overtones. Not sure if the hammering introduces more work hardening, a surface shot peening effect, or more snake oil

[David Ball]

I started spinning cones back in the 80's. I found certain brands of aluminum flashing that worked quite well. I spun mine on a male form--wish I had tried your approach! But it worked well for me. I used a rounded wooden dowel as a spinning tool with a lot of vaseline on it as a lubricant to try to keep the work hardening to a minimum. I think a certain amount of work hardening was good, but if it got to be too much, it behaved like non annealed metal and tended to get ripply. And yes, those sharp edges spinning on the lathe would be scary if not for leather gloves!

Later on, I vacuum formed plastic cones, much like a lot of speakers use. They were mellower than the aluminum but were still very strong and sounded good. Plus, I could do them in cool colors! (I used plastic plates for my material. Vacuumed in the spiral ridges too). I had a Mattel "Vac U Form" toy as a kid, and sort of mimicked that using my shop vac as a vacuum source.

Dave

[Tim Toberer]

Maybe you should go in the business.

I realized a while ago that the second my hobbies become a job, they are no longer as enjoyable. My goal is to have something at the end I would like to play and at some point someone else might also. I will say the markup on these cones is pretty insane considering the price of the material is pennies and they take about 10 minutes to make.

I started spinning cones back in the 80's. I found certain brands of aluminum flashing that worked quite well. I spun mine on a male form--wish I had tried your approach! But it worked well for me. I used a rounded wooden dowel as a spinning tool with a lot of vaseline on it as a lubricant to try to keep the work hardening to a minimum. I think a certain amount of work hardening was good, but if it got to be too much, it behaved like non annealed metal and tended to get ripply. And yes, those sharp edges spinning on the lathe would be scary if not for leather gloves!

Later on, I vacuum formed plastic cones, much like a lot of speakers use. They were mellower than the aluminum but were still very strong and sounded good. Plus, I could do them in cool colors! (I used plastic plates for my material. Vacuumed in the spiral ridges too). I had a Mattel "Vac U Form" toy as a kid, and sort of mimicked that using my shop vac as a vacuum source.

Very cool ideas there David! I have been looking into low tech vac forming for guitar building.

I have been going back over the cone to kind of even it out and harden the materiel. I agree that a level of work hardening is good. The trick is to get the cone formed before it needs to be annealed again. As long as you have the right aluminum this doesn't seem to be much of a problem.

[David Ball]

Agreed. If you've got the right aluminum, it works out well as long as it doesn't harden to the point where it needs to be re-annealed.

I'll try to find some pics of my vacuum formed plastic cones. I had a frame for those--I'd put a plastic plate in the frame and put it in the oven. When the plate drooped and then tightened back up, it was ready. Then I'd put it on the vacuum form. Worked great. And as I said earlier, the tone wasn't the really brilliant tone you get from an aluminum cone, but for ukes like I was making back then, the extra mellowness of the plastic cone was just the ticket.

Dave

[Tim Toberer]

I'll try to find some pics of my vacuum formed plastic cones.

Dave

That would be cool!

[Carl Mayer]

For quick and dirty vacuum forming those space bags for storing pillows and comforters work pretty well you just have to be more careful about sharp edges and such. Did that for a carbon fiber archtop I built a while back.





Just use a shop vac for the bulk of the air and the hand pump to finish it off since you can pull more with that.

Rest of the build pics are here if you’re interested

https://imgur.com/gallery/carbon-fiber ... ld-PhYX0XZ

Carbon fiber cones might be fun to play with too

[Mark Eaton]

The aluminum must be near pure aluminum and annealed. About .012 thick for biscuit and tricones. I think spider cones are thicker maybe .020 or so, not sure. Spider cones are cheap and available.

Cool topic Tim!

Are spider cones thicker than biscuit cones and tricones? I honestly don't know, have never thought about it in the past. I'm not much of a tricone or biscuit bridge player, have only dabbled with those types in the past.

I have been playing lap style dobro for 48 years, and as far as spider bridge cones, the Beard Legend for example is practically feather light and extremely thin. It also rings like a bell.

you wrote that spider cones are cheap and available. True - if they're the ones made in China, which often sound like crap. Spider bridge reso luthiers have been known to say that at minimum, 50% of the guitar's tone comes from the cone. It's why dobro players often buy inexpensive made in China resos but they upgrade them with a quality American-made cone and perhaps a #14 spider.

No doubt there's plenty of markup in a Beard, Scheerhorn or Replogle cone - but having those guys spin the cone for one's guitar might be a little like if you were having to deal with some legal issues, you hire a lawyer with a good reputation instead of settling for a random public defender.

[Tim Toberer]

The aluminum must be near pure aluminum and annealed. About .012 thick for biscuit and tricones. I think spider cones are thicker maybe .020 or so, not sure. Spider cones are cheap and available.

Cool topic Tim!

Are spider cones thicker than biscuit cones and tricones? I honestly don't know, have never thought about it in the past. I'm not much of a tricone or biscuit bridge player, have only dabbled with those types in the past.

I have been playing lap style dobro for 48 years, and as far as spider bridge cones, the Beard Legend for example is practically feather light and extremely thin. It also rings like a bell.

you wrote that spider cones are cheap and available. True - if they're the ones made in China, which often sound like crap. Spider bridge reso luthiers have been known to say that at minimum, 50% of the guitar's tone comes from the cone. It's why dobro players often buy inexpensive made in China resos but they upgrade them with a quality American-made cone and perhaps a #14 spider.

No doubt there's plenty of markup in a Beard, Scheerhorn or Replogle cone - but having those guys spin the cone for one's guitar might be a little like if you were having to deal with some legal issues, you hire a lawyer with a good reputation instead of settling for a random public defender.

Well my experience is rather limited. I bought one spider cone, yes cheap Chinese made. I measured the thickness and it was a bit thicker than the biscuit cone I had from national. I can't remember the exact thickness, definitely thicker. I have no doubt that a Beard cone would improve the tone, but I do enjoy the sounds I get from my guitar. Maybe I just got lucky, or I am just blissfully ignorant. At the time I just couldn't justify spending the money on a name brand cone cause I had no idea if my guitar was going to work out or not. Maybe next time I will try one. I don't think I will be spinning this though. They would be a bit more complicated.
I suppose have a strange sense when it comes to tones and sound. I can almost never say something sounds better, just different. For a long time I was obsessed with the tones of different acoustic guitars and I would go sit and play whatever new guitars they had at the local music and pawn shops. The more expensive instruments usually hove a more refined sound and play easier, but I was always more attracted to the rough strange sounding instruments. I was on the search for my forever instruments. In the end I fell in love with a couple Harmony guitars with ladder bracing, terrible action and huge baseball bat sized necks. More sound isn't always better, especially if you are not the best player lol! This isn't the best philosophy for a builder I realize, but my instruments may always be rough and strange.

[Tim Toberer]

For quick and dirty vacuum forming those space bags for storing pillows and comforters work pretty well you just have to be more careful about sharp edges and such. Did that for a carbon fiber archtop I built a while back.


https://imgur.com/gallery/carbon-fiber ... ld-PhYX0XZ

Carbon fiber cones might be fun to play with too

I like it!

[Carl Mayer]

Single point forming could be neat to try too if you wanna get really weird and make elliptical or square or guitar perimeter shaped cones. I think you could make some really cool instruments and hopefully get some disapproving looks from the traditionalists.

https://hackaday.com/2024/03/16/a-spif- ... ing-metal/

Doing it with cnc is obviously cool in that you can do it with no forms and probably necessary to get enough pressure for heavier stock but for this thin of stock I was daydreaming about doing it by hand with a drill or arbor press. I think you could scoot a clamped form (like you already have but doesn’t necessarily need to be circular) around underneath a little pivoting roller held in the chuck. Then just roll it around the perimeter a hundred times while you adjust the quill down a little at a time. Kinda like a tiny little English wheel.

[Chris Clem]

Resonator players are pretty much all "rootsy" type musicians. They will zero interest in carbon fiber cones. Bad idea, as a builder you need to know who your building for.

[Tim Toberer]

Resonator players are pretty much all "rootsy" type musicians. They will zero interest in carbon fiber cones. Bad idea, as a builder you need to know who your building for.

I agree there wouldn't be much interest in those, maybe until Jerry Douglas started playing one. It's not something I would be doing, but I don't see the harm in it and I would be curious how it sounds. Plastic cones for Ukes make a lot of sense and I think Uke players may be more open to this. I am just happy I produced something that may actually work. Once I confirm it does work I will probably move on to other aspects of my guitar, like bellcranks and changer fingers.

[Carl Mayer]

Resonator players are pretty much all "rootsy" type musicians. They will zero interest in carbon fiber cones. Bad idea, as a builder you need to know who your building for.

For sure there’s no market, which is it ironic since the resonator is both the most recent and drastic deviation from traditional acoustic guitars. Oh well, maybe they’ll find it in a closet in a hundred years and think it’s cool and vintage.

[Tim Toberer]

The great thing about cones is they can be replaced! I think of them not quite disposable like strings, but more like tuners. They wear out and different styles suit different people. That is part of the reason I don't care so much about fitting my guitars with name brand cones. If they ever make it out in the world, a player could upgrade if they wish. As a builder I am primarily concerned with getting things stable, easy to maintain and super playable. Also building guitars that will withstand the test of time. Tone is important, but it is so subjective.

In many ways carbon fiber seems like the perfect acoustic material. There is a guy building carbon fiber acoustic lap steels and the resonance is really mind blowing. People seem to like them and they go for big bucks. These guitars will probably outlast humanity.
https://www.youtube.com/watch?v=Z9Nwt1a1gBM

[David Ball]

I'll try to find some pics of my vacuum formed plastic cones.

Dave

That would be cool!

[Tim Toberer]

I'll try to find some pics of my vacuum formed plastic cones.

Dave

That would be cool!

Those look amazing!