One 'major' aspect of a 'set-up' is the fit of the tonering to the banjos wooden 'shell', which is called the 'rim'. As a repairman/Luthier, I put setting up a banjo into two main categories, which is 'general set-up' and a 'complete set-up'. A general set-up does not include taking the banjo apart to correct the fit of the various components, but only adjusting the banjo 'as-is' , making adjustments to the head, tailpiece, installing a good bridge,setting action there,etc. I will talk about those things later, in a future blog post.
There are three main components in a BG style banjo's 'pot assembly' (pot assembly refers to the round portion), which are : rim, tonering and flange. There are all kinds of tonering and flange configurations, as well as types of rims, in banjos in general, but for our discussions I will be referring to the two main types of bluegrass banjo types: flathead and archtop tonering banjos. The fit of the three main parts is a crucial aspect of the instrument's ultimate tone and playability. Let's take a look at the tonering and its fit to the wood rim in this article.
Tonerings are made from proprietary alloy formulas that are either unique to the ring designer's specs, and is their own unique alloy, or is a replica of 'prewar' formulas, based on rings made back in the 1930s by the Gibson Banjo Company. These old 30's tonerings were made from what is known as bell bronze metals. It is called bell bronze because bell makers have used it for over 1000 years or more. Bell brass is a slightly different alloy, also used in the making of instruments, although it is not as durable. Here's some good reading on the alloys:
There are two main types of ring configurations of bluegrass banjos today; the flathead and the archtop style, with some other types appearing occasionally, one being the 'ball bearing' style. lets concentrate here on the main two types. Here's some pictures of the differences in the two rings from a BHO topic and JDAM's website.
The banjo's tone and power can be dramatically altered, in positive and negative ways, by the fit of the tonering to the wood rim. There are 3 main contact areas on the wood rim. here's a shot of a flathead ring, resting on the 3 ply wood rim.
The outer portion of the tonering is called the 'skirt' and the upper portion that rests on the top ledge of the wood rim is called the 'bearing' surface. The inside facing portion of the skirt contacts a routed area on the rim also. This gives 3 critical areas of fit for the tonering: the skirt , the bearing and the inside skirt face. All three, ideally, should fit the rim in a certain way, to achieve best tone and response. How does each area need to fit in order to contribute to the set up of the banjo... I am glad you asked!
The most critical aspect of the tonering's fit is generally accepted to be its tightness to the rim. This means that the rim must not be fitted too tightly or too loosely, for best tone. In the 1960 and 70's it was thought that 'tighter is better," as far as how well the ring should be fitted to the rim. Later, it became apparent that the classic banjos from the 1930's did not have very tightly fitted rings. Most had what is now know as a 'slip fit'. This simply means the ring is not tightly fitted to the rim, but can be slipped on and off by hand, with not much effort. It does not have lots of 'slop', meaning no excessive e play (too loosely fitted) either, but is well centered on the rim. Having a very tightly fitted ring results in very metallic, 'pingy' tone and actually hurts the banjo's ability to resonate all frequencies it is capable of producing, especially mid and low tones.
Once the ring is properly fitted to the rim, the next two critical areas are the skirt and bearing fit. The skirt should not contact the portion of the rim below it first, so that it holds the ring too far above the top of the rim itself. Most luthiers/repair persons make sure that there is a tiny gap between the skirt and rim, so as not to impede the more important area, which is the bearing surface. The very top portion of the tonering is accepted as critical to overall tone and response. The ring should be fitted so that the area that rests on the rim's top area, must be fully seated and flush with it. There should be uniform contact over the entire circumference of the rim, with no gap between them. The rim is 'bearing' the load of the tonering, while the head is exerting downforce over the ring, pushing the two together. If the ring is fitted flush to the rim, the amount of energy needed to mate them together is not lost or wasted.
The structure of the archtop ring looks different than a flathead ring, but the seating and fitting aspects of the two are almost identical. Both must be well fitted and seated to do their jobs properly.
There are a plethora of flathead rings available on the parts market these days and all of them are well made and can sound wonderful in the right banjo, with the right set up. I could go on for months talking about each ring, but suffice it to say here that they are ALL great quality. It is an apple vs. apple debate for me. My advice is to read up on the rings, decide what you can afford and gravitate towards and buy it. The only sure way to know if that ring will be to your liking is to have it installed on a quality 3 play or block rim and be properly fitted to it.
I hope this short article was useful and helpful in understanding the tonering and its fit, in regards to the banjo's 'set-up'. Thanks for reading and see you next installment !
Tom Simurdak Says:
Tuesday, May 20, 2014 @3:58:08 PM
Mr Boulding, you are the best. Thanks for all the info.
Tuesday, May 20, 2014 @5:52:07 PM
Enjoyed your article on tone rings and fit I agree one hundred percent on the fit Thanks
Tuesday, May 20, 2014 @7:50:52 PM
I learned a lot about my banjo by taking it apart. I'd read about the 'just-so' fit. I fettled the rim until my once tight fitting ring could be fitted and removed by hand. The difference in the tone was remarkable! Difficult to describe, but more open and jangly. Stripping the banjo down should not be viewed as a scary proposition: you just need patience, and an uninterrupted afternoon!
Wednesday, May 21, 2014 @4:54:57 AM
I have never removed the tone ring from a BG style banjo - only disassembled basic old time banjos (brass ring resting on rim). So I have question - is the mating surface of the rim finished, or unfinished, where is is hidden behind the skirt area on the side of the rim?
Thanks. Just curious!
Wednesday, May 21, 2014 @5:33:13 AM
Most builders follow the prewar ideal, which is to leave the mating surface of the rim free of finish so that the tonering is seated against raw wood, both at the bearing surface and the area under the skirt. But I apply a coat of thin oil finish, which soaks into the wood, to seal it, without any build up to interfere with tonering mating.
Most builders leave the entire area free of any finish.
Wednesday, May 21, 2014 @6:57:37 AM
Thanks for the great information. I started out in the old school of tightly fitting tone rings and I felt kind of guilty about switching over to a slip fit, and this makes me feel a lot better. I also like the idea of using a thin coat of oil finish. I usually don't (again, I've been bound by tradition) but I think it would have to help keep things stable.
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