Official Luthiers Forum!

Hi fellas,

I am fitting the Martin G13NR009 2 way rods for the first time.
These differ a little from the LMI/Allied rods I have used in the past.

The rod is completely coated in plastic wrap, and is rounded on the bottom.
It appears the rod is nominally 1/4" wide and 3/8" wide for 2 inches at the at the adjustment end.

Question for those that have used these:
Should the slot be rounded at the bottom?
Are these glued into place or installed dry?
Also, I assume the slot needs to be a bit wider than 1/4" to allow for the plastic wrap.

Thanks!

Rob

Ping John Hall at Bluescreek

I just use a 1/4in bit and it fits right in. A rounded bit would be nice but I use a straight one. This kind of goes over to my 'removable truss rod' thread but I always glued those in dry by using a piece of masking tape over it as I apply the glue then remove the tape and clamp the fret bard down. After it's glued up you can pull the rod right out. The adjustment end is a bit wider. ON my guitars that extension is in the head block so I just use a round rasp and make it a bit wider.

I went out and bought 1/4" and 3/8" core box bits to rout the slot with a round bottom.
For you repair guys, how does Martin route these slots?
Any glue at the ends?
I don't want any rattles.

Rob

I use those rods, and that bit. The rod will push in with medium thumb pressure, just sneak up on the depth. Not much room for a rattle, but a drop or three of any glue to take up any movement.

B

_________________
My memory is so good, sometimes I remember things that never happened.

We mill a round-bottomed slot to 0.365"-0.370" based on actual rod measurement (they vary a few thousandths). We used to mill a flat-bottomed slot at about 0.300 and use a 1/4" piece of drill rod to scrap the bottom to a round shape, but the router is faster and more consistent.

We mill the adjuster area out with a standard two flute end mill or spiral router bit - far enough into the neck that a stress riser is not a factor.

The rod is not glued in, but we also don't do anything to keep glue from the slot, and some will penetrate, but the heat-shrink sheath will not permit rattles in any case. If sloppy with glue, it's a good idea to tape over the operating end of the rod such that the tape can be pulled after the glue dries.

FWIW, there are big differences between the Martin-style rod and the sort-of-look-alikes sold by StewMac and on Ebay...we use only the Martin rods, after dissecting a Martin and a few look-alike rod side-by-side.

_________________
For the times they are a changin'

- Bob Dylan

Excellent, thanks Woodie and Bri!
Exactly the info I was looking for.
And yes, these rods came directly from the Martin 1833 shop. Nice folks there, BTW...

Cheers!

Rob

That's what I've been using with good results.

In the instructions that came with my first build, a Martin factory kit, they said to fill the slot with white glue or Titebond before inserting the rod. I don't do that but I also epoxy my fingerboards to the neck to avoid introducing any moisture which can cause back-bow. I know some of the excess epoxy goes into the slot to reduce the potential for rattles.

Kevin Looker

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

These are the best rods in my opinion.
I buy them from Martin.
I use a 1/4" round bottom bit and bed the rod in with yellow glue as I am gluing the fretboard on.

Doesn’t gluing it in cause it to be limited in the length of the adjustment? I’m sure Martin knows what they are doing but it seems kind of unintuitive to me.

My own personal view:

Like a few other 2 way truss rods, the Martin rods have a flat bar on top and a round bar on the bottom. It is often said that, with a flat bar on top, you don’t need a filler strip on top; you can just have the flat bar against the bottom of the fingerboard.

However, I prefer to make the slot just a smidge deeper than needed and use a filler strip on top of the flat bar anyway. Why? Because that makes sure the bar is as snug as possible inside the neck, thereby helping reduce the chances of a rattle. I just put the rod in, glue the strip in, clamp it down, and plane it level with the neck after it dries.

only use these and I use tite bond just to fill the voids .

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it