Official Luthiers Forum!

Most of the time it has not been a problem, but a few times I have had a problem with LMI or Allied's 2 way truss rods rattling on me after the guitars have been made.
I wonder how everyone is using silicone (or something else) to keep this from happening. A few dabs on the ends, or a more generous full length bead in the bottom of the slot? What about between the round rod and flat bar?
I route a round bottom slot, and glue a wood cap over the top of the rod. I think the rattle is the two rods hitting each other more than the rod being loose in the neck.
Has anyone else had this happen?
What do you do to prevent it?

I route the rod groove about 1/16" too deep and fill with a wood spacer on top. Then I clamp and epoxy the spacer in place with gentle pressure and the rods will stay in contact to keep them from rattling. If you use too much pressure the rod can bind. Don't ask me how I know.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Allied have a rubber sleeve on the bottom rod - I have been usingthese for years now (even the old ones did IIRC .... I have only ever heard the rod ratel on me a couple times, and a slight tighening stops it, as you change the resonant freq of the rod. I dont use any sealant inthe trough bottom (the runner is down there already).

I had a student come over a couple weeks ago and complained he was hearing a rattle - I tightened the rod a touch, didnt go away - turns out it was the tuner washers being loose under the threaded lock nut - simple fix !!!! check them every once and a while, snug them up - they do come loose as the wood/finish shrinks.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I had an LMI rod rattle on me when I first started using them and tightening did not help. I injected rubber cement into the trough through a 1/16" hole at the third and tenth frets. Used a cut off needle for a tight fit and injected until I saw stuff coming out the other hole. Filled the holes with a sliver of ebony/dust/CA and they were invisible. This was a Frank Ford tip. He diluted the rubber cement with naptha but I wound up using it almost straight from the bottle with very little dilution as I recall.
Ever since then I run a bead of caulk down the channel where the lower rod rests and lately have added a filler strip on top. No rattles to date on about 25 guitars.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I'm working on a neck that is not yet on the guitar and I just tried something new. I put down a piece of saran wrap over the slot and then pushed the rod down into the slot encased in the saran wrap and the rattle that was bothering me is gone. I reasoned that the saran wrap will contain the silicon and keep it out of the neck. By the way, the saran wrap is 1/2 of a thousanth of an inch, .0005"
I pulled the rod out, put down a fresh piece of saran wrap, applied some silicon and pushed it home and it seems fine.
For adhering a wooden cap over the shiny medal rod I tried a using piece of double stick carpet tape, which is some seriously sticky stuff. Then cut the excess saran wrap out of there and was able to plane the cap down flush. The cap will bear right against the underside of the fingerboard.
I can't make the rod rattle in any state of looseness or tightness so I am happy with it.

If you need to fix the rattling rod in existing necks, you can pickup some of that rubber tool handle dip - Permatex is the brand I think. Thin it down with mineral spirits. Pull a fret that is as far away from the truss rod adjustment as possible, but still over the rod channel. Drill a small hole through the fret slot into the rod channel. Inject the rubber solution into the hole, while applying vacuum at the adjustment end.

Thanks to Stephen White for this tip. It's saved a few necks for us.

In my opinion, the only way to install these dual-action rods (Allied and LMI) is to use a filler strip. I can literally bang as hard as possible on the back of the neck and not hear a single thing - and this is with the rod having no tension. Contrast that to not using a filler strip and there is a world of difference. Just route your slot about 1/16" deeper and then epoxy in a filler strip atop the truss-rod and apply mild clamping force in the center (I use spring clamps). Also, remember to test these rods before you install them. If you follow this method you will never have any issues.

SimonF speaks the truth !!!!!!

Mark

What about cutting your channel flush as per the instructions,and running a small bead of silicone on top of the flat part of the rod when glueing on the fingerboard.It seems like that would accomplish the same thing .
James

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James W Bolan
Nashville Tennessee

James,
Here is why the spline method is your best option. The spline and truss-rod are clamped down into the slot. All slack between the metal rods is taken up and the ends of the truss-rod are pushed with a fair amount of force down into the neck. I use spring clamps to clamp the center of the truss-rod and use cam clamps to do both ends. The other benefit is that the fretboard is glued to a wooden spline instead of metal and you don't have to worry about glue seeping into the channel and possibly interfering with the rods function. Sure the other way will probably work adequalely most of the time. But I notice that my necks tap equally well before and after the addition of the truss-rod. This one extra step isn't that big a deal and I would never install it any other way.

I would be very wary about placing caulk on top of the flat bar - the caulk could squeeze out and interfere with the glue underneath your fretboard.

Not to mention the myriad of issues with finishing that many caulk ingredients could possibly cause.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy