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Post by leeophonic on Feb 22, 2018 21:32:28 GMT
I came across this and found it interesting, refreshing to discover someone I had not heard of.
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Post by Stevie on Feb 23, 2018 9:08:25 GMT
Yep. Good.
As a yoof and with the savagely early passing of our Mum, Dad used to take us to work when there was no care available. A whole day with nothing to do is really boring for a child I can tell you! The factory was a sheet metal ducting company established in a disused abattoir, so all the sheeties had their own concrete alcove in which to work. The company diversified into making non-stick frying pans upstairs and I used to watch transfixed at a guy called Charlie spinning the pan carcasses. This may explain my background of which some on here may/will be aware. I have used hand wound circle cutters many times, but I've not tried spinning. I noticed that the tool(s) used in the video did not have ball races on the end? Mojo? Ha! Having done a great deal of swaging, I was hoping to see how they put the spiral swages into the cones so neatly and accurately because I cannot envisage how they do it. Must be custom press tooling because an ordinary jenny would deform the cone. Sadly, that was not forthcoming for the kind of cones being spun. Nevertheless, thanks muchly for this, I greatly enjoyed it. +1.
e&oe...
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Post by snakehips on Feb 23, 2018 11:32:40 GMT
Hi there !
I don't think they do an embossed spiral. It very much looks like the Quarterman type cone, without the domed area under the biscuit, which I believe is another important part of the all important whole !
I have always wondered how the spinners control the thickness of the metal, unless they just spin and then measure the thickness each time, until it reaches the desired thin-ness !
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Post by Michael Messer on Feb 23, 2018 11:43:27 GMT
These are modern Quarterman cones. They have no spirals and are pretty much the same as original 1960s/70s OMI Dobro 10.5" biscuit and spider cones. Their Dobro (spider bridge) cones are excellent. I have a Dobro here at the moment with a short spider on one of their cones and it is very good. I have never liked 10.5" biscuit cones, with or without spirals. They always sound dull to me.
Shine On
Michael
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Post by Michael Messer on Feb 23, 2018 11:46:11 GMT
The control of thickness is done by a calculation and feel. They use a thicker gauge so it ends up as the correct gauge. This is both a calculation and 'feel' or experience...
Shine On
Michael
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Post by linkous on Feb 25, 2018 13:05:30 GMT
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Post by Stevie on Feb 25, 2018 16:52:44 GMT
As already qualified, I've not attempted any metal spinning, but I offer these opinions;
Spinning is a finely controlled method of metal stretching. The spinning is carried out against a form or arbour. As the spun material approaches the intended profile, it will become thinner due to the stretching process. The inside surface of a spun cone is stretched less than the outside surface. The final thickness is ultimately controlled by the originally selected blank gauge and varies dependant upon how far down the cone you measure it because after any degree of spinning, the cone will be thinner at the peripherary than it is at the apex. The "feel" is limited to knowing how far you can push it either in a single pass, or ultimately after repeated passes over different arbours before the job almost instantly resembles the work of an over-zealous clay pot turner at his or her wheel. I do not Google or Wikipedia things before posting and it's all past experience or applied common sense / reasoning, so my signature says it all really!
I defer to Linkous' most excellent practical example. Actions speak louder than thousands of words, mine or anyone's!
I thought that I had qualified my remark regarding swages when I stated "the kind of cones..." I have Mark's bible too. I would still like to know how they do the swages in cones. There is an excellent video of the blessed Don Young making cones, but I don't recall seeing how he achieved it either. I'm still guessing that it's some form of press tool rather than what could only otherwise be achieved freehand on a jenny.
Somebody must know!
e&oe...
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Post by mikenewport on Mar 6, 2018 21:53:18 GMT
Hiya,
I worked as a spinner in a holloware factory in my late teens for a very short period of time, making pots pans lids etc.
Feel and controlling thickness of metal - It's a bit like spreading margarine with a knife! You can end up with thickness at the outer of the disk and thinness at the inner of the disk with uneven pressure. So I kind of disagree with Stevie that "The inside surface of a spun cone is stretched less than the outside surface." The metal is so thin and malleable that you can feel the 'push' of the tool against the work, and it's possible to push a continuous hole into it. OOps done that ! It's feels not so much like bending metal over the mould, more like controlled pushing against a very solid object.
If you notice in the video at about 5.00 mins, he is holding the tool almost horizontal and finishes the pass with the tool at about 45 degrees. What he is doing is pushing right shoulder up and forward to get the same leverage from the start point at the centre to the lower outer point. So yes your control of pressure, which also makes the circular spinning marks, and the uniform thickness is all down to touch and experience, which probably takes years.
Thickness of finished cone - If you accept what I have said about the importance of 'feel' in producing the cone, then the thickness is easy to figure out. The original Dopyra cones must have been arrived at by trial and error. A 9 1/2" cone as an example. If you were to start with a 7" blank stretch and work the aluminium to cover the mould and the cone collapses, you have obviously stretched it too much. A 12" blank may give you too much thickness and 2" to trim off and could result in a dead sound. So finding the initial correct cone for least working, practical strength and best resonance is the ultimate aim. Once you have the 'best' blank the rest is just production line.
Swages - I didn't know they were called that! My guess is something like this. The mould has a centre pin onto which the discs are located, so with the lathe open you place another thin steel form including the swage protrusions, soldered or brazed on to the pin, put in the spun cone. On the right hand side of the lathe there is a reverse or female mould, perhaps rubber faced. Close and tighten the lathe and the indents will appear on the outside of the cone. This would be done on a press probably, but the lathe illustration keeps it simple.
As an aside, we didn't use oil but a grease, all the spinners would cycle home at night looking like coal miners!
Haven't been about on the forum for awhile but I do drop in now and again and it's still the best forum on the net. Keep on resonating. Mike
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Post by Stevie on Mar 6, 2018 22:57:27 GMT
What a great post! I still have to get my head around how the cone can be a heavier gauge at the perimeter than it is nearer the middle / apex, it doesn't make sense to me but no way would I take issue with the fact unless I had actually tried it myself, I reckon I just need more visualisation to get there... I think we're agreed that the swages (if used) must be done on some type of press tool, but the analogy with using the lathe as the press made me start to wonder whether there's indeed a way to do it on a lathe. Fascinating, and thanks again for the input / clarification. +10!
e&oe...
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Post by Ian McWee on Mar 7, 2018 15:42:25 GMT
Just to throw a curve-ball into the mix here ~ many years ago I met up with Bill Johnson, the 'metal' half of the Beltona Resonator Guitars duo alongside partner Steve Evans.
Bill pressed the bodies and all other metalwork along with spinning his own cones and showed me the lathe / presses he used ~ when questioned about adding the spirals he confessed to just using a wooden cooking spatula and pressing them in by hand.....although he wouldn't show us that specific operation!!
Slide On!
Ian.
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Post by Deleted on Mar 7, 2018 20:04:41 GMT
In June 2011, my son and I visited the NRP plant in California. Don introduced us to, and we watched the fellow spinning cones there...sorry I was shy to photograph him, though we got some nice shots of Don and the plant.
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Post by mikenewport on Mar 7, 2018 22:10:44 GMT
Ok Stevie for your visualisations try to think of spinning being more like plastering/rendering, if you've done that, I always end up with thicker plaster at the bottom than waste height. I'm hopeless at plastering as well ha ha! Its the same sort of feel. It's not the same as 'panel beating' or beating brass because steel, brass, bronze etc are more at the rigid / brittle end of the scale than aluminium.
Another visualisation, when you're sliding on your guitar from say 5th fret to 7th fret, I bet you don't hit the 6th fret. You dig in with the slide but your controlled pressure prevents unwanted contact, but if you wished to hit the 6th fret it would be easy to achieve. Looking at the analogy side on, the string line which is parallel to the fret board, could be seen as outer and inner surface of the aluminium cone. Don't hit the 6th fret you have parallel lines, hit the 6th fret you get thinner in the middle. Thank you for such a generous score by the way!
Hi Ian, not such a curved ball I fancy. It's so easy to dent a cone and likewise pushing a small dent back out as described by MM in these pages. So just imagine putting your cone in a colander (cooking theme) and pushing into the holes from inside the cone with the blunt end of a pencil (dimples?). I think it would be easyish to spin a heavy blank on the same mould that the cone was spun on, cut your swage positions to suit and use it as a female mould to place your cone in. My brother who also worked as a spinner, spun a HEAVY aluminium, dished steering wheel once for a lotus 7. It was very rigid and he cut the holes around the centre by hand. My brother went on to be an engineer so I'll give him a spare cone, and say how can I make one of these. Roughly and by hand, you could use the spatula to press down into the gap on a workmate bench or a route in a piece of wood, but it's a bit imprecise for me.
I've always been impressed with the hand made louvres on car bonnets myself. Thinking about it, they would be great on a tri-plate.
Mike
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Post by creolian on Mar 8, 2018 0:10:13 GMT
Hello Mike, all, Pardon the OT... My early school days were absorbed in drawing louvred hot-rods, choppers and the attendant rat finks. Typical murican edumacation in the 60s... If you are not familiar, You might get a kick out of "terraplane" reso guitars. www.terraplaneguitars.com/Neat topic, thanks! All best, Jeff |
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Post by Dessery on Mar 8, 2018 6:47:34 GMT
Hi all
I watched many years ago a series of YouTube videos of a factory tour of NRP in California, each video focused on a different department in the factory, one of which was the cone spinners and they talked trough the process.
Try as I might, I can't seem to find it now, there is only one part available which isn't the cone spinning. I believe they were done by Lenny so I am wondering if they were removed when his reputation went downhill.
If anyone comes across it though, it's well worth a watch.
All the best
David
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