Hey all, I just got a new Gibson trapdoor banjo. (see the thread in collector's corner.)
The action was crazy high towards the pot. I went to adjust the co-rod. There's a coupling nut that connects the lab bolt in the neck to the coordinator rod. It turns out that the coupling bolt doesn't fit the lag bolt. The lag bolt is way too small, you can slide the coupling nut on and off.
I guess my question is: is it better to try to find a new coupling nut to fit the lag in my neck? Or should I figure out the threads on my coupling nut and find a lag bolt to fit that?
I'm not a luthier; I build wooden kayaks. So I'm looking for the solution that's less likely to wreck my banjo.
Happy to hear any advice.
Not sure what the hell the person who put that neck on was thinking...
I'd say keep the original Gibson parts, if possible, so changing the hanger bolt ought to be the way to go. Take off the nut and figure out what size and thread you need (and make sure the nut's not stripped out).
If you can't find a hanger bolt with the right machine thread, you might have to improvise something. Maybe putting a threaded insert in the heel? Machining down and (re)threading a lag bolt or slightly oversized hanger bolt?
N.B.: I kinda doubt that your neck is made this way, but on the original trapdoors, the back bolt is NOT screwed into the heel. It is a plain rod with one end threaded, and the other end bent at a right angle. To remove it you need to remove the heel cap!
And... I can't see in the photos how the heel fits the pot, and it may be that getting the neck angle right may also require recutting the heel. Once you have the neck tight on the pot, the action should be right with the co-rods "neutral"-- neither pushing or pulling on the tailpiece end. Using the co-rods to adjust the neck angle does so by distorting the rim, which should be avoided.
Thanks Dan. I'm kind of inclined the same way; keep as much Gibson stuff as possible. I'll take the coupler to the hardware store next time I go to find out the exact threads and then I'll see if I can find a hanger bolt to match.
I'm a little shocked how this happened. I'm led to believe the conversion had been done by a luthier, and the neck lag bolt isn't something a player is likely to arbitrarily swap out at home, which means some pro let it leave his shop this way? Or maybe some regular joe player tried to do the conversion himself, messed it up, and threw it to auction to bury his shame?
Anyway, it's liberating to have a banjo that isn't my main banjo. I can monkey with it and if I make a mistake, I'm still playing my main banjo .
Banjo neck attachment bolts (lag bolts unofficially) come in several strange thread sizes not generally found in hardware stores. Recording King and other imported banjos often have metric size bolts. Bolts should be available from most any banjo maker or luthier who probably has a selection of various sized bolts on hand.
I think a good bet for the correct parts would be to contact Richie Dotson at Acoustic Box
acousticbox.com/
Edited by - Pick-A-Lick on 12/08/2024 08:16:56
Just got home from a jam. One of my buddies is an antique car guy and knows a machinist. If I can't find the right bolt, he's confident this guy can fabricate something. Score!
Mike, I'm in your debt. That acousticbox site looks like a treasure trove!
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