Official Luthiers Forum!

I use the 2 way double action, welded nut LMI truss rod (TRSD) - with access from the sound hole. In previous builds, I've routed the channel deep enough to lay a shim on top of the truss rod, then plane and scrap the neck flush where the fretboard is glued to it.

Is it necessary to use the shim? If I want to route the channel less deep, so that the truss rod is flush with the top neck where the fretboard is glued, will I cause issues/ rattles? Anyone else do it this way? Thanks.

You can do it that way but i found it better to drop the rod down below the soundboard for easier adjustment clearance from the soundboard. It also helps keep glue away from your rod as well. You can use cauck at the ends and middle to keep the rod from rattling either way you do it.

There are folks that do just that and say it works fine; however, there is no question in my mind that installing a filler strip is a superior method. In my opinion, you should be able to rap the back of the neck very hard all along the length of the rod and not hearing anything. Additionally, a common "fix" for truss-rod rattle is to make sure the rod is under tension. If you don't have to worry about that with a Taylor then you shouldn't have to worry about it with a handmade guitar. My advice is to keep doing what you are doing. In the scheme of things, it doesn't take too much extra time to install a filler strip.

Best Regards,
Simon

I used to not bother with the filler strip, but after watching Robbie O'Brien's tips on how to install the double rod with a strip compressing the center down, I tried it that way on my last build. In my opinion, that is a superior method, the neck came out with no rattles in the truss rod compartment, and rings with a strong clear bell tone. I did the installation without any caulking.

The advantage of not using the strip is that the rod is supposedly removeable, but in order to be removeable it has to be loose enough to remove, which, even if it's tight enough to stay in place, it still rattles around unless you have a little bit of tension on it. I find that sometimes even with tension, they can still rattle, and/or vibrate sympathetically with certain notes, and sometimes the neck is stiff enough to not need much trussing, so you can't tighten it enough to eliminate the rattle unless you mill every neck with enough relief to ensure that you must truss it enough. The strip on top eliminates both problems.

My strip os only about a milimeter thick, thicker in the middle where it compresses the loosenes, so I can still make a nice thin neck if needed.

Here's the video: http://www.lmii.com/CartTwo/DisplayVideo.asp

_________________
Old growth, shmold growth!

I put two shims down the sides of the channel about in the middle. They squeeze the rod to prevent lateral vibrations. Also, once the neck is in place, I put a bit of tension on the rod, which kills any vibrations along its length. I have never used a filler strip other than on an electric where the rod channel was curved and needed a corrosponding curved filler strip to help the action of the rod when adjusted. I can see however that having something between the fretboard and the guitar neck would help keep the fretboard from being popped off if the glue joint were to wear out in the future.

_________________
http://www.sixgunguitars.com

Does the filler strip limit how slim you can have the neck?

I've done it both ways - with and without the shim. It seems to me that a shim would have no effect on the rod rattling because this is caused by cutting the slot to wide or to deep without having any tension on the rod. Lately I have not used a shim and have been applying a dry lubricant (bicycle chain wax lube) on the threads and the top and side of the truss rod. This makes it impossible for glue to mess up the threads or to stick to the rod. Because the wax lubricant is allowed to dry before placing it in the truss rod slot, there is no effect to glue adhesion anywhere except the truss rod.



Yes - it reduces the possible neck thickness by the thickness of the shim. This shouldn't have an impact if you keep the strip thin, but it is something that should be used in calculating the thickness of your neck. If you are worried about it, you could make your fretboard a little thinner.

_________________
"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

My rod turns perfectly smoothly, no hangup whatsoever. In fact it even seems more responsive.

_________________
Old growth, shmold growth!

On the LMI or Allied type rods the shim does two things: it will compress the flat bar down to the rod itself preventing any rattle. So essentially the shim is thicker in the middle of the rod. Second a mahogany or maple shim is easy enough to plane level with the neck wood, metal is harder on tools. The lower it sits in the neck, the more effective it is.
I would be reluctant to put anything like wax, lubricant or silicone in the neck as it can contaminate the wood, and is not necessary.

_________________
Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Silicone - forget about it - that would be nuts.
Wax that is dry will not contaminate wood unless you rub it around on it - not a bright idea. The wax lube I use goes on wet and dries in a few minutes. I don't think it is any more risky than using wax paper. With minimal care I have good results and I never worry about a lack of adhession to the wood joints or adhession of the glue to the truss rod bars or threads.
BTW - Finish carpenters rub candles on nails and screws all the time to allow these fasteners to slide in easily and not crack hardwoods.

_________________
"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Thanks, all. Great feedback. Thinking I'll continue to use it.