Attached below is a photo of a thumbscrew and resonator wall lug from my 70s RB-250.
I have never seen a wall lug with threads like this. Instead of screw-like circumferential spiral threads, they're sort of fluted. They're curved, of course, but no thread completely circles the shaft. The thumbscrew looks different than most that I've seen. But I haven't seen them all.
Can anyone who has disassembled stock 70s Gibsons tell me if these are consistent with factory original equipment?
The banjo had several non-Gibson parts that I've replaced with period-correct Gibson or Gibson-sourced from other periods. Just for the fun of it. So finally getting around to asking about these.
Greetings: I have a mid 70's RB800, all original. It's wall lugs are two parts, the lug which is threaded like a machine screw; this screws into a threaded sleeve which is set inside the resonator wall. The sleeve locks into the reso wall by the spiral flutes. For years I thought they were one piece. If you look close at yours, the actual lug protrudes through the outer sleeve. I think I finally oiled the pieces, held the lug in a very small vice and used padded pliers to unscrew the sleeve.
The thumbscrew looks like mine....different/smaller profile and 8-32 threads vs what we now consider standard 10-32 and thicker profile. Thanks, Shawn
that is correct Shawn - the "fluted sleeve" is a separate part from the wall lug. i have also seen these come out of the sidewall of the resonator when the lug is removed. is should come off the lug easily enough. sometimes they can be a bit stubborn, but if care is used, one can get the two parts separated.
Thanks so much, guys. Right you are!
I can't believe I never noticed that the tip of the thumbscrew was visible at the end of the lug shaft.
Three of the four inserts are stuck on the lugs. I imagine I can loosen the screws from the lugs with PB Blaster. That stuff has worked on the most stubborn parts. Then I'll clean the threads on both parts, and tighten the inserts' fit in their holes. The fourth one that's staying put just needs a little thread cleaning to prevent its lug from locking.
As suggested, the thumbscrews are threaded smaller/finer (than modern day). Interesting that the screws still go into newer lugs, just sloppily. Also, the lug shafts are threaded smaller/finer than the newer lugs. So new lugs are not a drop-in replacement for these.
Since this is all original equipment, no need to change.
find a bolt the proper thread size, but longer - about 1inch to 1 1/2 inch should be sufficient. put the sleeve on the end of the bolt. Then PRESS the sleeve back into the hole it goes in, in the sidewall of the resonator. BE CAREFUL - it doesn't take too much pressure to overshoot the sidewall and push the sleeve clean thru it! To help ensure you don't do that, make sure the bolt you use is long enough to give yourself a proper grip, - before putting the sleeve on the end of the bolt, first put a nut that is the proper thread, and a washer next to the nut; THEN put the sleeve right on the end of the bolt. That way the washer can act as a stop to prevent accidentally pushing the sleeve thru the resonator sidewall. those sleeves are just pressed into the sidewall. you can put a small amount of adhesive in the hole or on the outside of the sleeve to help make sure the sleeve stays put. and don't screw the lugs back in super tight when putting it all back together!
Before you posted this, I figured out that pressing the sleeve in was the waay to go. I used the lugs. Screwed them in almost all the way. Pressed in with a clamp and padding on outside. Didn't occur to me I could push the sleeve all the way through and fortunately that didn't happen.
Reason I took them out in the first place is the locations aren't working. This is my RB250 that a previous owner converted from multi-ply rim and two-piece flange to 3-ply and 1-piece. From the time I've owned it, the setup is off. The neck was all the way to one side of the notch in the resonator. I've fixed that a bit, by better centering the flange, but it's still not right. And all 4 lugs don't line up with their T- brackets.
SO -- I'm getting ready to send the resonator for refinishing to eliminate a large worn-to-the-wod spot. I'm using this opportunity to see if I can finally figure out if the banjo just needs correct assembly or if the lugs are in fact mis-located. If they are, that's something else I'll have fixed when the resonator's being refinished.
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