The Fetching Gretsch

Gretsch 5120 - Tuning Stability Issues/New Nut and Bridge

On the bench today, we have a Gretsch Model 5120 that belongs to local punk, rock, and garage-o-tronic musician, Dust A.C., who uses this as his main axe in a few projects, most notably Antilogical and grrRoPoLis.

It's a pretty cool looking guitar, but the stock plastic nut, bigsby, and floating TOM bridge were creating some tuning stability issues. Dust wanted to have a locking nut installed, but we both agreed that all the extra modern hardware and hex nuts just wouldn't fit the rockabilly Gretsch decor.

A lot of tuning issues on vibrato equipped guitars come from strings getting bound in the nut slots. As the strings slacken during vibrato use , they move in the slot, bind at a different point, and are prevented from returning to tune. I recommended a Black Tusq self lubricating graphite composite nut from Graph Tech. An old school home remedy for sticky nuts (you heard me...) has been to rub a graphite pencil in the slots to keep it lubricated. Since the Black Tusq is made of graphite, it does the job for you.

Another binding point can often be the saddles themselves, so I recommended Mr. A.C. go with a different bridge configuration. After a little research into roller bridges, I realized that the relatively flat neck angle and stack height of the 5120 might not be enough to allow the roller saddles to move. A quick browse around the Gretsch forums brought me to the highly recommended Tru Arc bridge, a properly radiused, bridge that utilizes a wrap around design for unencumbered string travel. Shipping took a little longer than normal due to some supply shortages, but Tru Arc owner, Tim Harman was helpful and patiently answered all of my concerned emails during the order process.

Here are a couple of shots of Dust's axe as it came to me:


I dig the slick, jet black vibe this guitar has without the pickguard, though it is a little difficult to see under all the sweat and gig grime.

Here's a good shot of the old bridge. It's not uncommon for a gigging/player instrument to have this level of grime. In fact, I would totally expect it from someone as busy as Dust A.C. All of this crud (mostly pieces of hand) gives a guitar serious street cred, but it does take it's toll on an instrument. Check this out:

Take a look at the floating bridge base and bridge height adjustment thumbwheels. That brown stuff in the middle and on the thumbwheels is more gunk that was causing corrosion on the bridge posts. The wheels were starting to rust to the posts, something that would have made future bridge height adjustments much more difficult if it was allowed to go unchecked. I hit the bridge posts with naptha and a toothbrush for about 10 minutes each before I could get the posts clean enough to oil and re-thread the wheels back on.

This is the old bridge, also pretty gunk-ified. After looking at this thing I was pretty sure that this was part of the tuning problem. Although the saddles are slotted, the slots have just become magnets for more string snagging crud. A lot of the complaints coming from the Gretsch forums was that the OEM bridge wasn't slotted to match the fingerboard radius as well, causing the strings to hit the frets in the wrong places as they neared the bridge.

A quick pic of the cleaned thumbwheels after soaking in naptha for about 15 minutes. Shiny, shiny...

With the wheels clean, bridge posts free of debris and oiled, frets polished, body wiped down, and fingerboard cleaned and conditioned, it was time to start putting the 5120 back together. Check out the Tru Arc ST-120 Rocking Bar Bridge:

The firs pic shows the nice matching 12" radius, and the second is a good illustration of how the bridge is machined to receive the strings and hold them in proper alignment without giving them a place to hang up when you wiggle the bigsby. It dropped in without a hitch

Here's the pre-strung, post cleaned black beauty:


The next step is to shape, slot, locate, cut, reshape, re-slot, polish and install the new nut. I've spared you about 20 photos of me with various files, sandpapers, saws, and polishing compound since it's a pretty dull process and can be found elsewhere on the web by guys like the master: Dan Erlewine .

Here's a nice shot of the Gretsch all strung up with the nut roughed in but not finally trimmed and polished.

Hey! What happened to my nice clean bench?!

In the middle of the process, my three-year-old wandered in to see what I was doing and noticed immediately that he could look directly into the output jack and see into the body of the guitar.

As usual, I got so caught up in what I was doing that I forgot to snap a pic of the finished nut. Here's one I took when I was about 2/3rds of the way finished. The rough shape and slots are there, but the final shaping, slotting, and polishing remains. I think it was about here that I realized that yellow glue doesn't stick to graphite. I had to scrape it out of the slot and stick the nut down with a couple of drops of thinned out superglue.

With the bridge in and the nut set, it was time to turn to the intonation. The Tru Arc bridge doesn't employ individually adjustable saddles, so you have to take a "best of all possible worlds" approach by positioning the bridge where most of the strings have the best intonation. I used painter's tape to give me a reference point as i made some final adjustments to the relief and nut, but short of pinning the bridge, (major surgery) only string tension holds the bridge in place and allows it to make solid contact with the top.

Here's the final product all cased up and ready to go back to kick out some serious jams with Dust A.C.
I can't wait for the next time I can check it out live!


Next up: I restring and set up a bargain basement acoustic for my nephew.