Anchoring a 2 way truss rod in a kentucky

[atetone]

I have a kentucky 350S that the trussrod came loose in.
I took the fingerboard off and just slid the trussrod out.
I can't figure out how it was supposed to stay attached in there. It wasn't glued in and has no anchoring end.
It was just sitting in the routered groove free to slide around.
Also no filler strip covering the trussrod, just the fingerboard.
Can anyone shed some light on this for me?

[atetone]

Ooops,,,, I mistakenly called this a 2 way trussrod when in fact it only tensions one way.
It has a tube that holds the adjustment screw and parallel to the tube is a flat bar which is attached to the tube at both ends only.
When you tighten the screw with an allen wrench the flat bar bows creating a space between the tube and the flat bar.
I am now starting to think that this thing was designed so that the flat bar pushes against the underside of the fingerboard which forces the neck into a backwards motion.
If I am correct then all of the stress of tightening is carried by the fingerboard. Strange. That is a lot of stress on the glue joint holding the fingerboard on.
Maybe I am wrong.
I will try to post a picture of it

[atetone]

Wow, I can't believe it worked! That has never happened before.
This is it in the tensioned position.

[Desert Rose]

This is a VERY very common design and has been in the market for about a decade and a half

It IS designed for the flat to push on the fretboard and in fact doesnt work well if a filler strip is used at all

Although this is a one way rod it works similar to most two way rods on the market including the most popular hot rod

This design with the round rod and flat has been available from Luthiers Mercantile for a long time its on their website I know

If there is any concern that this may cause a problem with the glued fingerboard then the problem is one hundred percent with the fingerboard gluing operation not the rod design

Ibanez electric guitars have used this for longer than I can remember and the factory when I worked there made about 185 guitars a day like this. Multiply that by six days a week and about fifteen years or more and thats a lot of good market input about the reliability of the design

All this being said there are very simple ways to do a little effort to anchor the rod for stability and to avoid the danger of rattles, it looks like Kentucky did nothing on that mandolin

Scott

[atetone]

Thanks Scott.
There was quite a dent in the underside of the fretboard caused by the flat bar so that is why I was questioning the design. Still seems strange to me but I guess it has worked for a long time on lots of instruments.
So now I have to decide if I am going to just put it back in and re-glue the fretboard back on but I might still end up with it sliding around in there. I guess that the intent was that you put enough tension on it to stop it from sliding around.
Of course if I do that then I would have to admit to myself that I didn't need to take the board off in the first place!
Live and learn I guess.
I might look into doing something different with it since I have it apart anyway. Maybe a traditional trussrod or maybe I will experiment with a carbon fiber rod.
I will have to ponder this for a while.

[Lex Luthier]

When I worked for an acoustic guitar builder he did his truss rods the exact same way. To prevent the rods from rattling he applied a bead of a silicone/rubbery glue into the slot before installing the rod. He also layed a piece of masking tape over the rod when applying the glue.

[Desert Rose]

Lex

Exactly

Thats the recomended process with these rods

Scott

[Jim Hilburn]

Once some pressure is applied it will lock it in place.

[atetone]

Thanks guys.
It looks like I didn't need to take the fingerboard off at all.
I just needed to apply a small amount of pressure.
I though it was the threaded rod type and had broken, but apparently not.
That's ok though. It is a good learning experience.
I think I will take your advice and silicone it back in and give it another try.
I might as well make a bone nut for it while I am at it and flatten the neck before re-installing the fretboard.
What kind of glue should I use to glue the fingerboard back on? I am not versed in hot hide glue so I need a different alternative.

[Jim Hilburn]

I use a custom version of this type of rod, but I would never use any silicone products in my shop. Your begging for finish problems. A latex sealer maybe or just some tape or just a snug fit.

[atetone]

Thanks Jim,,, I will use something latex-based.

[Desert Rose]

Jim is EXACTLY right aboutreal silicone!

Buy the non silicone type at Home Depot, the kind that stays always flexible like silicone type and it not only anchors but combats buzzes

Scott

[Desert Rose]

Jim is EXACTLY right aboutreal silicone!

Buy the non silicone type at Home Depot, the kind that stays always flexible like silicone type and it not only anchors but combats buzzes

Scott