National RM-1 bridge problem

[Jim Garber]

I started playing my RM-1 at a couple of OT jams and it was going well. Lots of volume -- I can finally hear myself.

Then, last night, halfway thru the jam, the E-strings suddenly came out of their grooves. I replaced them but from then on if I played the E-strings they popped out. Obviously the strings must have worn the edges off the grooves. I tried to not hit those strings too hard but it happened anyway.

The big problem is that National built these with a cover over the bridge and it looks like it is riveted on on mine. It looks like I would need to take off the strings and the cover plate in order to get to the bridge.

Has anyone had this problem and/or worked on these new Nationals? All suggestions would be appreciated.

[Shelagh Moore]

They are not rivets fixing the cover to the plate but small Allen bolts. If my memory serves me, the Allen key size is around 1.2mm. In any case, I have removed the cover and worked on the bridge on my RM-1.

[Jim Garber]

Richard: thanks a lot. My eyes are not so young... of course, it would make a lot more sense to have that art removable.

Did you have a similar problem? From what I can see the angle of the E-string from the tailpiece when looking down (not sideways view) looks sharpest on the outside strings and I figure that the top of the slot may have lost its edge somehow.

Aha, I even have a set of metric and SAE Allen wrenches I bought some time ago from Radio Shack. Excellent. Now I just have to not mess up the bridge.

[Ray(T)]

Yes, they are allen bolts but I've never needed to take mine off. The problem with working on the saddle is probably going to be that you could end up with it too low. I'd be interested to know whether the saddle and biscuit are in one or two pieces and whether the biscuit is glued onto the cone.

Might be worth asking the people at National. I found them very helpful when I was looking for a matching strap button. They sent me one free, gratis and for nothing.

[Jim Garber]

Thanks. Actually I did email them today.

[John Morton]

The Allen screws should fit a 1/16" key. The nearest metric wrench would be 1.5mm.

I always use a triangular file, one with the sharpest possible corners, tilting it slightly downhill towards the tailpiece. The string soon wears the wood into a nice U-groove which lasts a surprisingly long time. You might want to tape over the coverplate openings to keep the sawdust out.

[Jim Garber]

Thanks, John. I will try that.

[jim simpson]

The cover being removable seems like an improvement over the originals. The bridge is typically glued into the round "biscuit", the biscuit it secured with a screw through the resonator cone.

[Ray(T)]

I assume you haven't found this Jim. http://store.nationalguitars.com/biscuit-1.aspx

$10 seems like a bit of a steal.

[Jim Garber]

Excellent! I may need that if i screw up the one on it at the moment.

[Jim Garber]

I heard from National and the guy there says the Allen wrench size is .050". I just tried the wrenches on mine and 1/16" and the 1.5mm are both too big. The two smallest ones I have in the Radio Shack set are 3/64" (.046875) and the 1.27mm (.050"). I tried the 1.27mm and that seems to work the best. Now I just have to make sure that the bolts don't fall in the holes in the cover plate or get lost altogether. Yikes!! I will definitely tape the coverplate holes before I start on this.

Man, this RM-1 is addictive. I took out one of my regular mandolins and it is so quiet in comparison.

[Jim Garber]

Thanks, everyone, for your advice and help. I finally had some time this evening and adequate light and magnifiers to see what I was doing. My vision is not all that great closeup but I have a stationery magnifier so i could actually see the slots on the bridge. I have a couple of set of needle files and tried a few of those but finally found that the best thing was some cheap welding tip cleaners that worked well to get the front of the grooves down a hair enough so that the strings don't pop out. I will be at a noisy music party tomorrow night and see if that did the trick or not. So far it is much better than it was, so I am hoping that is it.

I am really enjoying playing this mandolin more and more. It is nice to know that the volume it there if I need it but it sounds pretty sweet ever when played softly. I do have to watch out for the echo and the sustain else it gets might muddy.