Sanding a cone question for Michael (and anyone else)

[gaucho]

Hi Michael,

Awhile back we were discussing the unique tone you can only seem to get from a vintage cone and you mentioned sanding the modern cones to make them lighter. I have replaced the Hot Rod cones in my 2 vintage Nationals with vintage cones (love the change!) and now find myself with 2 HotRods sitting in my closet. I searched for the old thread but no luck. I seem to recall you saying that a HR cone weighs about 9oz and you liked to sand them down to about 6oz. Does that sound about right? I'm going to give it a shot (I, of course, assume all responsibility for my actions!!) and try the cone in one of my more modern guitars. Did you use the wet/dry sandpaper wetted, and what grit do you suggest? Is it necessary to start off coarse and go to fine paper? I don't care how it looks and it's the underside of the cone. Did you sand in any particular pattern, like maybe with the spirals? Thanks for any tips you can give and again, I completely understand that I stand an excellent chance of ruining the cone!

[snakehips]

Hi there !

I'd need to find the notes I made once (if I knew where they were) - so I'm going mainly from memory here, instead.

Years back, I bought digital kitchen scales and used them specifically to weight resonator cones.

If I remember correctly, vintage cones I weighed were around 24.5g
NRP Hot-Rod cones were around 25g
I think NRP non-hot-rod cones were about 26g
An old Quarterman non-spiral cone was 30g

Thus, on the cone weight, NRP hot-rod cones are the closest, and actually quite close to vintage National cones.

I think I measured a Continental cone, from a MM Lightnin', when I was putting a NRP hot-rod cone in it.
I don't remember how much it weighed to be fair BUT I remember it being more than NRP cones of both type but less than the thick gauge Quarterman cone.

The Quarterman cone came from a National I bought on ebay. The neck needed a reset so the guitar did not sound optimal BUT I remember I was quite surprised at how decent the Quarterman cone did actually sound. I must try it in one of my guitars again, for a laugh !

If I am bored enough tonight, I'll get out my kitchen scales and weigh the variety of spare cones I have.

As for sanding those cones, I'd strongly suggest you will do more harm to your cone and it's sound than you might gain - and thus advise NOT to do it !!

Not wanting to be an angel of doom here but on the balance of things, I can't necessarily see NRP still operating in 50yrs time - and as such, spare decent resonator cones (of which their hot-rod cones are arguably the best around) may end up fairly scarce in the future.
I'd keep those cones unscathed and safe if I were you. If the old National cones in the Nationals you have found eventually fail, you have these hot-rod cones to replace them with. Or, if you buy ANOTHER National (apparently, they are quite more-ish !) and the original cone is gubbed / replaced with something rubbish, you are going to need a good one to go in it. If decent cones are rare in the future, you are gonna be glad you kept your spares safe !

[tobi]

Interesting Question.
I wonder if electropolishing also would work. The method is possible on aluminum.
en.wikipedia.org/wiki/Electropolishing

[resonatorman]

I also weigh every cone I come across - and they vary a little.
The vintage cones are lightest, but not all have 24 g.
The Hotrods are from 25-28 g, the lightest I ever had (and play today) has 25,7 g.
The NRP cones from the 90s (pre-Hotrod) are around 30 g.
Continental I can't remember.
A non-spiral Johnson chinamade cone had indeed 40 g! Sounded the like...

[Michael Messer]

Hi Gaucho,

I have never actually done this to a cone, but I was told about it by British musician, luthier and ex Notting Hillbilly, Steve Phillips, who has done it to an early NRP cone.

I don't believe he kept weighing it, just worked it by feel and it was a successful experiment.

Here's what he told me....

Get a large bucket of wet sand and lay cling-film (Saran Wrap) on the top, push the upside down cone into the cling-film-covered sand so it is really sitting in a firm solid bed, using wet/dry (don't know what grit) Steve patiently and slowly worked in circles with the spirals until he felt he had removed enough, and as far as I know, that was how he did it. Steve is a master luthier, an artist and a very patient person, so the only advice I can offer you, is don't rush this. I played the guitar that Steve built with this cone fitted and it sounded excellent.

I have a set of 6 inch Triplate cones from 1928 that were re-spun because they were damaged. They have been in my guitar for over ten years and they sound great. This is also a hit-&-miss thing to do, because some cones just fall to pieces when re-spun and some don't.

Cone spinning is not a science that done by using weights and measures, it is an art that is done by feel and experience. Each cone spinner has their own touch and 'feel' for doing it.

IMO, the closest to vintage National cones being made today are Mike Lewis's Fine Resophonic cones. Mike very rarely sells them as spares, he only fits them into his own instruments.

Shine On
Michael

[snakehips]

Hi there !

I'm a bit confused with the idea of re-spinning a vintage cone.

I was under the impression that a vintage National cone starts as a flat sheet of thin metal, then it's spun on a lathe, pressed against a conical former, from the middle, to the outside,essentially to press out the aliminium sheet thinner. At this stage the cone would now begin to look like a finished product except it still needs stamped to give it it's embossed spiral pattern AND the corrugated rim.

How do you re-spin a cone when it already has spiral embossed pattern, and corregated edges ?

[Michael Messer]

...it was a long time ago. Dave King did them for a while, but because it was a bit hit & miss and because Dave thought it might have weakened the cones, he stopped doing it.

Interestingly, mine are still fine all these years later.

I would need to ask Dave how he did it to answer your question. I am seeing him this week, if I remember to, I will ask him.

Shine On
Michael

[gaucho]

After sanding, my HR cone is now down to 24grams. I weighed it before, but it was on the scale at the post office and it showed the weight as .9oz before and after. I know that's not right! From what's been posted, 24g seems pretty close to the vintage cone weight. I'll report back after I install it...

[resonatorman]

24 g is great! Having read all this, I think I'll give it a try with bucket'o'sand method...