buzz from a resonator cone... what to do?

Hi, all -

I have a National ukulele that is a few years old and in great shape overall. But I've noticed a small buzz coming from the biscuit/cone area on the C string (not on all C's, just the open C string). It happens most of the time when the C is plucked (especially near where the neck meets the body), and the buzz definitely seems to be coming from the biscuit area, but could be anywhere in the cone. It also can be heard when strumming chords that include an open C.

Could you please provide some guidance as to what things I should look for, and where to begin? I'm comfortable opening it up to troubleshoot if necessary, with some guidance, but I'm unfamiliar with resonators, so I don't want to do too much until I know what I'm looking for and if there's anything in particular I should be careful NOT to do! I appreciate any thoughts on how to proceed... and of course, if it's so delicate or fiddly that I should just leave it to an experienced tech, that's okay too!

Thanks very much,

Christina

▶ Reply to This

Replies to This Discussion

Permalink Reply by Greg Miller on June 21, 2020 at 1:00pm

Greg, thanks for the reply. IRT the biscuit gluing to the cone, I agree with you which is also what Stewmac techs as well as Dan E. says. Although they do say if gluing is a preference use wood glue. I'll doubly agree with you especially for an aluminum biscuit to an aluminum cone which is how the the National Revolution is tha wood glue makes absolutely no sense.

However, with the aluminum biscuit machine screw and washer I still think that threadlock (the low torque breakaway grade would be called for). An even better approach would be a different screw (pan/flange head eliminating the washer with a nylon key eliminating the need for threadlock).

IRT the break angle between the saddle and tailpiece I'll with the 5 to 7 degrees which is about where it is now before setup. The action at 12th fret is 1/16 on both the bass and treble so it isn't much off where I want it.

The guitar is marketed through Dean made in Korea and I believe made in the Samick factory. Although Dean says the serial number is on the headstock it isn't so I'll go hunting for it elsewhere when I have the guitar apart. Being my first resonator, I wanted to start with a low/mid range one in good shape.

I'll try getting some pictures during the week and send them. Greg Miller