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 ARCHIVED TOPIC: Harry Sparks - Mack Smith AT to FH Conversion Ring


Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/382922

550Spyder - Posted - 04/30/2022:  12:44:32


Does anyone have pictures of a Harry Sparks / Mack Smith archtop to flathead conversion tone ring? I understand not many were made in the 60's and they're somewhat unique. PM me if you care to comment offline. Thanks

Oldtwanger - Posted - 04/30/2022:  13:19:12


quote:

Originally posted by 550Spyder

Does anyone have pictures of a Harry Sparks / Mack Smith archtop to flathead conversion tone ring? I understand not many were made in the 60's and they're somewhat unique. PM me if you care to comment offline. Thanks






The Harry Sparks/Mac Smith raised head to flathead Conversion tonering



As told to me by Harry Sparks:



The Sparks low-profile flathead conversion tonerings were cast by Richard A Hibner, Central Brass 
Foundry, 1020 Woodrow St, Cincinnati Ohio. Hibner wanted to add magnesium to the alloy but Sparks insisted on no magnesium in the alloy; he had to pay for every casting, defective or not, because of this spec.



The ring was not copied from an actual original Gibson low profile as found in the Royal PT style 6. Sparks used the measurements and alloy analysis from an original full height flathead no-hole tonering, from 9467-5, but profile was redrawn to keep everything the same as a full height ring just altering the angle to raise step by ¼ inch. It turned out to be virtually identical to the 1929 era Gibson originals minus the 20 holes.



Hundreds were marketed and installed by FOTMC
(Famous Old Time Music Company, Cincinatti) and Stewart – MacDonald. StewMac could not stamp them with the 5-star logo as the skirt would crack due to the brittle nature of the alloy.



I have never seen one with holes, and I have never seen an original with no holes.



Frank Schoepf



.

550Spyder - Posted - 04/30/2022:  14:33:01


quote:

Originally posted by Oldtwanger

quote:

Originally posted by 550Spyder

Does anyone have pictures of a Harry Sparks / Mack Smith archtop to flathead conversion tone ring? I understand not many were made in the 60's and they're somewhat unique. PM me if you care to comment offline. Thanks






As told to me by Harry Sparks:

 






Thanks Frank.  I'm hoping to see pictures to see the machining characteristics.  It is interesting to hear about the Mg spec.  I also have a very reliable source that Stewmac carried them briefly but dropped them when they didn't sell well.



It sounds like the Sparks/Smith rings were no-hole and possibly were closer to the 3lb weight than the low-profile rings in the PT-6.  Is that accurate?

RB3 - Posted - 04/30/2022:  22:06:30


I can add a little to what Frank has already provided. Harry and I have talked about this many times.



Harry had the metallurgical analysis done by someone in the Mechanical Engineering department at the University Of Cincinnati using mass spectrometry. The analysis revealed that the material was basically bell bronze. The composition was 80% copper and 20% tin, but there were very small traces of other elements. The metallurgist who did the analysis advised Harry that the amount of the other elements was so small, that he judged their presence to have been the result of contamination during the casting process. He also advised Harry to make sure that the castings were made with copper and tin from virgin ingots, i.e., material that had not been re-cycled.



When Harry began contacting foundries to have the castings made, he was told that they could not cast 80-20 bell bronze. At some point, he pressed the foundry people to explain why they could not cast the material. The guy from the foundry said, "Well, actually, we can cast it, but you won't be able to live with the volume of scrap that we'll produce". As Frank explained, Harry paid for the scrap, and insisted that the rings were cast as 80-20 bell bronze.



They were very good tone rings. Mack had an arch top tenor with a conversion neck and one of their rings. It was a helluva' banjo.


Edited by - RB3 on 04/30/2022 22:09:13

hbick2 - Posted - 05/01/2022:  04:52:23


I will be seeing Sparky in a few days, so I will ask him for more information.



One detail I distinctly remember had to do with the turning of the rings. The original Gibson rings were turned with carbide burs rather than diamond burs. Sparky had his rings turned with carbide burs because he said that the heat generated by the burs worked hardened the metal and caused it to have a different sound. The owner of the shop that was to turn them was reluctant to use carbide but did so anyway. According to Sparky, when he began to turn the rings, the noise was so deafening that everyone else left the shop. He ended up having to turn them at night, when the shop was closed.



If you want to hear Sparky talk about the development of the conversion ring, you can watch an interview that he did several years ago for NAMM. Here is the link:



namm.org/library/oral-history/harry-sparks



Select the full interview and go to about 27 minutes in to hear about the tone ring, and especially the metallurgy. There are some great interviews on the NAMM site as part of their oral history project. Just type the person's last name into the search box.



namm.org/library/oral-history/all

550Spyder - Posted - 05/01/2022:  08:32:37


My question was more basic. Is there anything uniquely distinct about the rings that if someone handed you one you could say this is a Sparks/Smith ring.

I'm always curious about the metallurgy side and it's the first time I've heard of using a magnesium flux. My understanding is it's usually used with magnesium alloys and does affect hardening. The 80-20 standard doesn't show any Mg.

There were several ring makers that were using 80-20 in the 60s-70's but my experience is Gibson did not. Gibson may have used it in the earliest archtops but highly doubt it was used in the 30's.

There are 80-20 ingots which will have some trace elements within the standard and not necessarily from contamination. It may depend on if the foundry reused crucibles for similar alloys.

Regardless of the bronze alloy it takes about 20 pounds of material to get a rough casting of about 7 pounds and then machined to a 3 pound ring. The gates and risers scrap would be recycled by the foundry and the rest of the scrap by the machinist. My experience is scrap for recycling is always figured into the cost of both.

I left a message for "Sparky" yesterday and hope to hear from him soon.

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