Truss Rod Adjustment - Help!

[Steve Cosgrove]

Hello everyone. I am a longtime guitar player but relatively new at doing my own set-ups. I am trying to learn about truss rod adjustments, I have an old Harmony H802 guitar (my first guitar) that has been sitting in my closet for about 20 years. The guitar never played right, I could never play it past the 3rd fret because the action was so high. This week I took the guitar and I put a carpenters square across the fretboard to look at the curvature of the neck and indeed there is a severe up bow. I measured the string action on the low E string at the 7th fret and the string is about 7/32" above the fret.

 

Since the bow is so large I started tightening the truss rods in increments that are larger than recommended (1/4 - 1/2 turns). Anyway I have gotten to the point where I can not tighten the truss rod anymore and I still have a  measured action of 1/8" (4/32") at the 7th fret and would like to get the action down to 1/16" (by the way its a tune-o-matic bridge set for its lowest setting).

After tightening the truss rod to it's max, is there anything else that I can do to try and relieve the rest of the bow? 

 

Thanks in advance for the you advice and recommendations, its much appreciated.

 

Steve

   

[Mike Kolb]

If it were mine, I'd slack the truss rod nut to 'neutral' (just prior to grabbing) and remove the strings. Figure-out a way to clamp the neck into a straight position (I use the surface of a table saw) and let it set for a couple of days, making sure the truss rod is still slack at that point.

Now's a good time to lightly oil the truss rod nut and make sure the threads are in good shape. Then retighten the truss rod slowly while the neck is still clamped. The nut should (the famous "should") tighten the truss rod down far enough now to hold the neck straight... or at least take it past the point that it had stopped working for you. The theory being that asking a truss rod to remove a set bow without assistance is asking too much of it, and we need to help it out some.

Once you've established that the neck can be straightened somewhat, then you can reclamp it and use short spacing blocks to establish a backbow condition, which will get you where you need to be for restringing and truss rod adjustments. If you find you're actually "running out of threads" to tighten, you can gain a bit by slipping a thick washer over the end of the truss rod and gain a turn or two.

[Steve Cosgrove]

Hi Mike - Thanks for the input. I do have a few question just to better understand your method.

1) I do have a set-up where I can clamp to neck straight (and even apply a back-bow if neccesary). How does straightening the neck with a loose truss rod help me? After the neck is clamped straight for a couple of days won't it just spring back it's original bowed position OR when I release the clamp or it return to a new less bowed position?

My initial assumption was that it would be beneficial to tighten the truss rod while the neck was clamped straight and this would allow me to null out the resistance of the bowed wood.

2) Am I correct in thinking that if I slip a washer over the end of hte truss rod nut that this will cause the truss rod to bottom out earlier than normal? Does this actually allow the truss rod to create a larger back bow thus allowing the neck to come back to its straight position?

Thanks for the great info.

[Mike Kolb]

Hi Steve... I usually let the neck sit, clamped straight (or backbowed slightly) for a few days just to "stretch" the wood away from where it wants to sit. Yes, it'll tend to spring back, but less than it had been. I probably didn't explain myself correctly, but you're correct about wanting to tighten the truss rod while the neck's clamped back to null-out the resistance. Anything to help the truss rod do it's job is a good thing. Just cranking-away has broken more than a few.... and that's a sound that's not soon forgotten.

In regards to the washer, I'll use one when the nut has "bottomed-out" and has run out of rod thread to travel. The washer needs to be just barely larger in diameter than the rod and yet still sit flush on the neck wall. It's a cheap trick and it only buys a turn, at best... but sometimes that's plenty. The real fix there would be StewMac's truss rod rescue kit, but that's pricey at just about $235. Check-out "step 3" on "how it works" to get a picture of how a washer would come into play, assuming you have plenty of thread already and just need to cinch-up the nut sooner before running out of room.

http://www.stewmac.com/shop/Tools/Special_tools_for_Truss_rods/Trus...

[Greg Mirken]

First, with a straightedge resting on the first fret and over the heel, what is the gap now over the center of the neck, say at the 6th or 7th fret?

Some general thoughts- on older guitars it's a good idea to remove the trussrod nut and put a drop of lube on the threads before trying to crank down on it. Also it will work better if there's no string tension fighting it; you can even clamp the neck flat while you tighten the rod. Part of the reason for high action on this guitar is probably due to the body distorting causing the neck block to rotate.

[Bob Steinarsson]

Take a look at this thread: http://fretsnet.ning.com/forum/topics/flattening-a-warped-neck?comm...

The ironed neck is still as good as it was just after the repair.

BS

[Steve Cosgrove]

Hi Guys, well I really screwed up this time. I was slowly working the neck to get it straight. I had clamped the neck straight for 3 days, tightened the truss rod and tightened the strings, I still had 1/8" bow at the 7th fret. I followed Mike's advice, loosened the truss rod and put the guitar into a backbow for 2 1/2 days (using the method illustrated here: http://www.youtube.com/watch?v=e2HGn7c9_uo ).

After I tightened the rod and re-strung the guitar I still had the 1/8" bow. I decided to tighten the truss rod somemore and SNAP!!!! I was able to remove the truss, it snapped at its anchored end. Now I would like to remove the fretboard from the neck of the guitar to look to see how the truss rod was anchored and remove the piece that snapped off. Can someone walk through this. It looks like there is a laquer over both neck and side of the fret board, My first assumption is that I would need to score the layer of laquer with a razor....then what?

Thank for the help.

[Mike Kolb]

Ouch & double-ouch. Sorry that happened, Steve. It's sure not fun to hear that sound. But it's not the end of the world and now's a good chance to get on intimate terms with the beast. Yes, score the lacquer at the fingerboard line. Remove the nut. Take out the frets.... if you do it carefully, you might be able to reuse them, but don't count on it. You'll probably become a refret expert in the process.

Not sure what you've got around the shop, but you can lay a triple-layer of aluminum foil over the fretboard and experiment with different hear settings on an iron to heat the board and slip the glue joint loose. You don't want it too hot, or the inlay dots will melt and burn. Low to medium heat over time is better than a hot, quick heat. When the glue is hot enough to let go (trial & error there), work a knife edge around the line you scored, looking for an opening. When you find one, work it slowly around the edges. Since the rod is already out, the best place to start the separation may be gently prying in the open hole

When you feel the board is about due to let go, it's worth it to find two small-diameter brads. Cut the heads from the brads. Drill 2 appropriate-sized holes through the fretboard and about 1/4" into the neck... one hole at the 2nd fret and another at the octave fret (the exact positions won't matter) so that you've made two "locate pins" to make sure you get the fretboard back to it's exact location when it's time to reglue. Make sure you drill into the actual fret slots, which will be covered later with frets.

You'll become a reftretter, a touch-up artist and a truss rod expert... all at once! Or you can take it to a local shop and see what the quote is.... it might be worth saving the all of the grief. Sorry to hear of the plight, but it may have a real silver lining. Updates, OK?

[Steve Cosgrove]

Mike - Thanks again for the info. This is a job that went terribly wrong. I used an iron steamed the neck and was able to get a couple of razor blades between the fretboard and the neck. I then took a putty knife and started to seperate the fretboard from the neck. All went well from the 24th to 15th fret, then the putty knife actually dug into the wood of the fretboard .......game over (actually the neck was ruined when I snapped the truss rod). It was a good learning experience and not much of a loss. I am currently looking on ebay for a new H802 neck, Good thing those guitars are a dime a dozen.

I will be back in the near future with somemore projects.

Steve