Steve Huber or Eric Sullivan can turn the flange to fit the rim.
Some people over the years have turned a rim to fit a flange but being it’s a prewar fat rim you have the right idea to turn a flange instead -

You can also use the 2nd generation flange - IF you wish to keep an original prewar flange on your instrument. Simply have it turned on a lathe just like you would a later / repro flange. Those are much easier to find and usually a LOT less expensive!

Thanks guys. I just found out Recording King makes 2 size flanges. One is 10 13/16 ID and the other 10 11/16 ID, which is 1st and 2nd gen specs. I just ordered the 13/16 which should fit if the upper diameter is 11"

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Originally posted by jellowaydan

Thanks guys. I just found out Recording King makes 2 size flanges. One is 10 13/16 ID and the other 10 11/16 ID, which is 1st and 2nd gen specs. I just ordered the 13/16 which should fit if the upper diameter is 11"

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I could be wrong (and there's a good chance I am), but I think the "fat boy" rim and the inner diameter it required in a flange were a bit larger than the 10-13/16 inner diameter of most of the pre-war era. I think it was first design that proved problematic for the flanges.

If that's the case, the new flange you ordered might require just a bit of metal removed to fit. Or: If the flange fits over the skirt area of the rim but wont easily go all the way to the interference ledge (whatever that area is called) you could have both the flange and that never-seen part of the rim turned for just the slightest bit of material removed.

Eric Sullivan did this for me maybe three or four years ago to make a post-war Doehler flange fit a 2000 RB-250 rim. A little bit of wood removed from the hidden area of the rim, and just enough metal removed from the flange to get it over the rim skirt. With the flange slightly warmed on a skillet it went on quickly.

If I'm wrong about the fat boy being different from the later pre-war rims and flanges, then the one you bought should fit with no adjustment needed.

Good luck, congrats on the acquisition, and have fun.

When I measured the rim it was 10.770 and only out of round by about.01. 10 13/16 is 10.812 which means about .02/side clearance. The dimension I’m concerned with is the diameter of the step which needs to be 11.003-11.005. I hope it will work right out of the box, but I’ll see

I believe Jimmy Cox did my fat rim (29 tb-2) conversion with his standard one-piece flange .
He cut for the ring,but not for the flange.

According to those in the know...Not Me!...The 1st gen flange was 25/32 ID which is .031 less than 13/16 so the RK flange with a 13/16 (26/32) ID will just fit. Ill keep you posted...It should be here next week

I have a fat rim style 1 conversion. Although the flange isn't broken, it is pulled up quite a bit. I am very curious to see if the flange you ordered fits. If it does, I think I'll order one.

Why would Gibson work on a flange to fit a "fat boy" rim when all they would need to do is fit the rim to the flange?

Well the sad news is it won’t fit!! The flange fits on the lower part of the rim but the upper part is 11” + and the flange is 10 15/16 dia so it needs to be turned to fit. Now I have a Prucha and a Recording King flange and wonder which one is better? I honestly can’t tell any difference so I think I’ll box it up and send it to Steve Huber

My understanding is the Prucha is supposed to be closer to pre-war spec. But as I was saying before, I think there were two pre-war sizes and the "fat boy" rim and its required flange were first and short-lived. So it probably makes no difference which one you use.

I believe Prucha made Gibson's flanges from the 1990s to 2009. If that's so, then with the Prucha you'd be using the same flange that went into Gibson banjos in a different era, just minus the logo. If that doesn't matter to you, use either one.

Good luck.

So I need more advice on this. Who in the building community can do this kind of work? Is Huber the only one out there, and for that matter this kind of job seems more of a nuisance than anything. Just trying to figure out my options here. FWIW- This seems like something that could be a service- having a few flanges on hand for this very thing