Resonator topic - dive in :)

A cone collapsed in one of my resonators. I was very concerned that this was a Howlett issue rather than the cone maker's. Since I had a pile of Republic cones lying around I fitted one, testing to see if it was the cone or not. The cone held up and hey, the ukulele sounded richer and better for it.

I have a National cone to fit in the one I am completing this week so will report on how that goes. The collapsed cone is another brand so I'm not going to share the name with you unless I see the National fail and it really is a design fault (which I am pretty sure it isn't).

What are your experiences with resonator instruments? This next will be my third and I was sure I got everything nailed with the prototype which is why I was so very concerend when the production uke cone's collapsed.

As you can see, on the edge of my comfort zone with this and need some feedback folks - and I hope this is refreshing to all those who all along knew that I didn't really know everything! :rofl: This is a serious case of peer review so hammer me with it and enjoy

Such humility Pete. Are you turning over a new leaf?

When I need to call it I will It's a defining moment when you don't really know what has gone wrong and there is no-one with sufficient knowledge to ask. You simply have to put your hands up, 'fess up, shut up and listen. I thought ya'll knew that about me. I don't have ALL the answers and this resonator thing is as much a dark art to me as some of the stuff the newbies publish needing to KNOW. Correct me if I am wrong (please) - to my knowledge, there hasn't been a thread on resonator break angle, cone collapse or cone comparison on this forum and since some are building these wonderful instruments I need, I'm sure others do also, some collective knowledge - I've shared enough of mine here, so help me out fellas

I can't imagine it being anything but cone failure due to defect. There just can't be enough pressure there to collapse a properly made cone. I imagine you are using a biscuit type and my experience is with spider setups so it is not quite the same but I've done plenty of "dobro" (sorry gibson) setups and the only time I've seen a cone collapse is when the owner tightened the adjustment screw too tight or strings too heavy of a gauge for the tuning they were using.

Great idea for a thread Pete. I have questions too:

1. Should there be some kind of fabric under the cone, in the well? I know older Nationals had something there. But some folks say it should be a hard smooth surface. I've built wells from plywood and considered putting some epoxy on the walls and the bottom.
2. I've heard that a 6 inch cone sinks about 2 mm when it settles, is that about right?
3. Is it best to fasten the biscuit with glue, a small screw, both, or just put a small pin in it that goes into the hole in the cone?

I'm sure I can think of more.

Sven

Some how the only thing I can here is......... ( When I asked a question about reso instruments )

No - that is far too overbuilt and complicated... I'm making some more soon so will probably film the process.

Pete Howlett Ukulele

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Sorry, ( not really ....... just had to add this). Our design will be ready shortly...... I didn't listen, sounds like I should be glad I didn't.

Blessings,

Kevin

My experience with resonators is pretty limited. I bought a National cone about a year ago but haven't used it yet....I swear I'll get around to that project someday.
So far it is holding up under the weight of the plastic wrapper very well.

Can I have the knackered one Pete?

Sven said:

Great idea for a thread Pete. I have questions too:
But some folks say it should be a hard smooth surface. I've built wells from plywood and considered putting some epoxy on the walls and the bottom.


Sven

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I heard of builders using ca glue on the rim the cone sits on to harden it up. I've never tried it. I can't imagine it makes that much difference but ya never know

Kevin you are not on topic - and it is never good to sneer... Both prototype and pre-prototype held up with sound body designs. The topic is CONES, not body design as was your thread.

I've never tried any of those Sven though have seen the felt 'cushion' many times. If you have the plywood well cut properly and the cone sits flat on it then it should be OK. I really think the cone maker applied too much pressure when spinning the cone and thinned it too much. Given what I know and looking again at the deformation I am given over to this view.

Yes the cone settles about 2mm - 3mm. In all 3 cases the cone would not settle evenly and leaned forward before collapse. The break angle was the same as both pre-prototype and prototype so I am now confident (after the success of the Repulic re-fit) that it was the cone. I am interested to know where others have seen collapse. And I did tension very evenly all three times gradually bring the instrument up to pitch over time.

Screwing the biscuit to the cone is the only way I know to do it. I use a self tapping screw with great care.

The trashed cone is no good - it won't hold up and once you have collapse you have lost everything - tone, intonation and volume.

Just let me know if you have had similar experience. I'm going to be sending them back when I have fitted the National cone in the next resonator and observed its progress.

Pete, can you upload a photo of the collapsed cone please? Just for interest.

A cone related question: How far from the uke top surface to the rim where the cone sits?

ukulele-melee said:

A cone related question: How far from the uke top surface to the rim where the cone sits?

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Depends on everything else.

My well depth started at 18mm. This makes for quite a tall saddle on the biscuit but it is the dimension used on National and other resos. When the first cone collapsed I assumed that the well rim was too narrow (completely forgetting that this rim had been OK in my prototypes and not inspecting the cone properly)so I made a 2.5mm thick insert 12mm wide. This had the effect of reducing the height of the saddle which I liked but made no difference to the break angle. I therefore conclude that it doesn't matter how high the cone sits because the string height is what it is. However, my well depths are now shallower reducing the saddle height which I think is very important since the saddles and biscuit become more stable and less susceptable to rotational torsion. The aperture in my cover plates is also larger than the National/Republic ones allowing for a wider saddle - essential if you are using a 42mm spacing at the cone end. So some minor design tweeks over those used by National and the others which make for greater structrual stability...

And to clarify - the cones collapsed when the instruments had exactly the same well depth dimensions as those used on National and other resonator instruments which I have measured and fully researched. This instrument was not just one of those ideas....

Pete, your design is close enough to mine so as not to quibble.

I also assume that cone well depth doesn't change the force acting on the cone. Not that I've done any rigorous testing.
Of course there's an extreme either way but I figure the asthetics will suffer before the forces cause a saddle-snapping-failure due to overly tall saddle.

The national biscuits are just big enough for my bridge string spacing, by a hair. You'd think they'd be more accomodating to me.

I haven't offered an opinion on your dramas because I'm very much in the R&D stage of resonator design/build, not because I don't want to. Good Luck. I'm learning from your dramas.

P.S. Aaron Keim offered some fantastic resonator (and general uke) set up advice when he was in cairns recently. There's no way I could have worked that stuff out on my own. I dare say he sets up more ukes per week than most.

On my prototype I made the well 12 mm deep, then with the "soundboard" it was around 13.5 mm. By some very lucky coincidencies that reso turned out very good. I'll check the neck angle.

That's the problem with this stuff Liam - there isn't a lot of 'knowledge'. The National tolerances are not good. There whole design piece was for their soprano so on a scale/aesthetic basis it doesn't translate for me to a tenor. It's why I have the cover plates made to my design... Hmmm, that is quite shallow Sven and I'd say your top is too thin. I'm with rufus on this when I say you make the instrument totally inert. It's why my top and back construction is plywood.

I'll show you my plywood skeletons Pete - they are nothing if not inert.

My first was built on a skeleton but I got a break with a small scale veneer press..

Pete,

Haven't been avoiding the post just been out of pocket.

1) You said poke.. I did....... my intent was not to hurt you personally.... I'm sorry my attempt at humor failed.

2) Sorry you feel I missed the point ... your cone failed. You missed my point ...... there are a number of reason that the cone could have failed besides the cone and material. The Tower of Pizza is leaning in part due to inadequate foundation and soils ....... same principle may apply here... also may not...... you could just have a bad cone.

We have finished our design of the reso uke and it has been one of the more challenging projects..... not a lot of room to work parts & pieces in place and the overall tolerance level is close. The height of the cone, the string load with the biscuit break, the plate that the bearing surface rest on, the cone overall placement in the instrument design and several other factors could have all contributed to the failure of your cone. In our design we reverse engineered several physical instruments that have lasted for several years. Being new at this instrument and not having physically built one I don't think you can ever go wrong with using several other established instruments as a bases for a design. Can it be done other ways sure..... everyone has an opinion. Airplane falls out of the sky design problem.... or material structural failure?

While the design we settled on may be overkill it may not be. Considering all factors the cone may have not been able to handle the load and stress placed on it. Another makers cone may not fail but again it may be simply a matter of materials and design given certain loads and stresses.

Enclosing few shots of our drawings as well as couple of shots of one of the actual instrument cone ledges that we based our drawings on.

Again Pete I'm Sorry for any mis-understandings.

Blessings,

Kevin