I use a router set up on a homemade router table so you very carefully take equal amounts of wood off all the way around the rim. Since that won’t correct the rim out of roundness fitting of the ring will correct that over time. You may have to help it along by applying a carpenter’s clamp for a few days in a humid environment.

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Originally posted by 1xsculler

I use a router set up on a homemade router table so you very carefully take equal amounts of wood off all the way around the rim. Since that won’t correct the rim out of roundness fitting of the ring will correct that over time. You may have to help it along by applying a carpenter’s clamp for a few days in a humid environment.

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Thank you for the great response! Good information. I recognize that most old rims  (especially the sub-mastertones with a single co-rod) have at least some out of round condition. It's when they are egged it gets difficult. 

I wonder what happens if you just leave the rim egged but cut a round seat for the skirt on the egged rim. The tone ring may not be perfect across the top of the rim (i.e., it may have overhang in some areas and setback in others)? Thanks!

One option might be to bring the rim back into roundness by installing a carpenter’s clamp across the rim at its largest diameter squeeze it intermittently to a little past round for a few days while it’s in a 200° sauna…check it frequently.

Be sure to check the flange as well. I have encountered ones where the flange egged over the years along with the rim. If you make the rim round, the flange may not go back on it.

Thanks all! Really great info. But going back to the original topic. Has anyone here successfully fit a Tone Ring on an out-of-round (or egged) pre war rim (without attempting to correct the rim)?

In other words, did you cut and fit a tone ring onto an out of round rim and eventually pull good tone from the banjo even though the rim/ring assembly is not perfect (i.e., some very slight setback inside, east and west, and some very slight overhang outside, at south, near tsilpiece).

When I had Jimmy Cox cut my '29 tb-2 rim (1 co-rod) he said I was lucky to have one as round as this.
He said it was tough to turn an out of round rim on the lathe.

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Originally posted by steve davis

When I had Jimmy Cox cut my '29 tb-2 rim (1 co-rod) he said I was lucky to have one as round as this.
He said it was tough to turn an out of round rim on the lathe.

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I figure it would wobble a bunch and tug on the rim. I was just wondering if anyone here did it and eventually got good tone, since it's still a PW rim. Sounds like you were fortunate that it was not an issue. Thanks!

Clamp it round and leave it that way for at least 6 months.

Heating a banjo to 200 degrees will cause about any glue used in luthiery to release. And probably cause the finish to release too.

If that's what you want, go for it but I would not recommend it. I'd recommend having a pro evaluate it. Especially a PW rim.

How out of round is it and as lightgauge suggested, is the tone ring round, and the flange?

Good recommendations would need more info.

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Originally posted by RBuddy

Heating a banjo to 200 degrees will cause about any glue used in luthiery to release. And probably cause the finish to release too.

If that's what you want, go for it but I would not recommend it. I'd recommend having a pro evaluate it. Especially a PW rim.

How out of round is it and as lightgauge suggested, is the tone ring round, and the flange?

Good recommendations would need more info.

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Thanks. This rim is about 1/8" out (maybe a little less). And my real question is whether anyone here has successfully fit a Tone Ring on an out-of-round pre war rim (without attempting to correct the rim)?

It seems like folks here generally suggest the rim be corrected first (usually with heat), but I am wondering if anyone has successfully fit a tone ring to an egged rim and ended up with a good banjo with solid tone. Thanks!!!
 

Is the out of round in line with the co-rod(s)?
If so the rods can adjust the 1/8 inch.

Severity of what you think as "out-of-round" would be important to know.

.....could be O-of-R by a few thousandths or O-of-R by 3/16".

So what are the measurements ? ....that is, after ring is removed, what are the two diametrically perpendicular, outside-to-outside measurements ?

(note: please don't let get us confused by whether your bottom line difference is based on radius or diameter calculations - just give us the two outside dimensions - we'll figure it out from there.)

And, as Steve Davis asks, give us some info regarding where the high points of the 'egg', or low points of the 'squish' are located relative to the neck to tailpiece axis.

Thanks! This rim is about 1/8" out, at top of rim, in line with and above the single co-rod that was overtightened for decades. A little more down by the co-rod area. Although I appreciate the suggestions, my real question is whether anyone here has successfully fit a Tone Ring on an out-of-round pre war rim, without first attempting to correct the rim? As someone mentioned, it would be hard to lathe and the TR will necessarily have some setback/overhang. Thanks!!!

It's so easy to correct the 1/8".
I don't understand the need to fit a round ring to an out of round rim.

I think most old rims are out of round to varying amounts, so yes. I had two turned for rings and flanges several years ago. I do not recall the amount of egg, but one more than the other. Both had similar results. With 1/8" you will have 1/16" overhang at opposing ends, so still a decent amount to seat to the top of rim. Not ideal, but functional.

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Originally posted by lightgauge

I think most old rims are out of round to varying amounts, so yes. I had two turned for rings and flanges several years ago. I do not recall the amount of egg, but one more than the other. Both had similar results. With 1/8" you will have 1/16" overhang at opposing ends, so still a decent amount to seat to the top of rim. Not ideal, but functional.

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Thank you!! That is an exact answer to what I was asking and also provided a good comparison. Did the one take longer to settle in? 

i know this wasn’t your question, but is it your goal to dissemble a prewar Gibson sub mastertone to install a full width and weight flat head tone ring. And, you’d like to accomplish this without any lathe work? And reassemble with same neck and coordinator rod setup?
Just wanted to throw out, I believe sub mastertone rims are physically taller and thinner in most cases. So to retain tension hoop perspective with neck, the top of your rim must be removed. And it requires harder to locate thin flathead rings designed to seat on your slimmer rim.

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Originally posted by Brett

i know this wasn’t your question, but is it your goal to dissemble a prewar Gibson sub mastertone to install a full width and weight flat head tone ring. And, you’d like to accomplish this without any lathe work? And reassemble with same neck and coordinator rod setup?
Just wanted to throw out, I believe sub mastertone rims are physically taller and thinner in most cases. So to retain tension hoop perspective with neck, the top of your rim must be removed. And it requires harder to locate thin flathead rings designed to seat on your slimmer rim.

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Yes and no. Adding a long-skirt full-weight flat head tone ring always requires cutting and lathe work on a PW rim with a OPF. Someone mentioned earlier that the original OPF may have stretched with the rim, which it did (at least it has assumed the same shape). The original OPF in this instance is flared and warped. So if I attempt to correct the rim too much, I probably can't use the original flange  In any event, I was just wondering how other conversions with these issues turned out. That's all. "LightGuage" seemed to answer that. Thx!

It has been a few years, but I do not recall any substantial difference in settling time. I know those old rims are harder and usually take longer, but usually worth the wait!

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Originally posted by lightgauge

It has been a few years, but I do not recall any substantial difference in settling time. I know those old rims are harder and usually take longer, but usually worth the wait!

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Good to know. Thanks for the answers!