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Epiphone 6730 Japan truss rod won't tighten any further

#1 User is offline   SSHolmes2019 

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Posted 09 March 2019 - 05:54 PM

Hello everyone, I'm new around here. I wanted to ask for advice on an old Epiphone "6730" made in Japan that's having some truss rod issues.
I've acquired this guitar a few months ago and converted it to play left handed. In the beginning I left the adjustable bridge that comes with it but
flipped the plastic saddle. I think the guitar had a good action when I got it but after I changed strings and made a bone nut, the action started to
bother me, making it hard to play.
Yeah, I know, I have issues with intonation because of my conversion to lefty but I tried compensating the new bone bone saddle that I made a few
days ago. The new bone saddle is 6mm thick, just like the slot, and I made it as low as possible to have low action.
After I made this new saddle I put some new strings (0.12) and I was hoping I could lower the action a bit more, so I tried adjusting the truss rod.
Turns out, it won't be tighten any further and the neck still has an up bow. The string action at the 12th fret is almost 6mm on the E string...very high!
What can I do to straighten the neck and get a low action?

My guitar has a bolt-on neck, could that be the problem? Maybe putting thinner strings could help?

#2 User is offline   QuestionMark 

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Posted 09 March 2019 - 09:55 PM

The truss rod isnít meant to adjust the action. At best itís meant to bow the neck in the event there is string buzz on the first three frets. FYI. Never tighten the truss rod too much as it will break. Also, FYI, the neck is not meant to be straight. It should be slightly bowed inward or outward around the 5-7 fret...the purpose of the truss rod being to loosen too tight of an inward bow or relieve too much of an outward bow. Or, to reverse the inward or outward bow by totally loosening the truss rod and the either working the inward or outward bow that forms with slight retightening. Either way only 1/8-1/4 turns at the most should occur...and, again if itís already tight, never tighten it further. Itís all more an art than a science. There are plenty of YouTube videos or internet articles in the subject of how a truss rod works regarding an innie or outie bow and how it functions..

Lowering the saddle will lower the action if it can be lowered. Adjusting the bow in the neck can to change the neckís bow so itís hump faces the strings at the 5-7th rather than away from the strings at the 5-7th fret can also help lower the action, but that would be done by loosening the truss rod and then playing with it with slight turns hoping the neckís mid hump forms facing the strings. There is no way to control if the hump forms inward or outward...making it an art to make truss rod adjustments.

You might just want to take it to a good luthier for a good set up after explaining what you are after.

Taking the neck off on a bolt on guitar, doesnít really do much, unless youíre skilled at adding slight shims to change the neckís angle and then being able to have the shims thin enough so the neck can tightly/seamlessly be put back on. Since, putting the strings back with tension on afterwards will change the neck angle with shims,..unless you are experienced youíll potentially be going down a rabbitís hole of guesswork (meaning youíll be adding or removing shims over and over hoping guesswork accomplished what the final angle should actually be.)

My advice it take it to a good luthier for a great setup.

Hope this helps.

QM aka ďJazzmanĒ Jeff

#3 User is offline   Late bloomer 

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Posted 14 March 2019 - 09:42 AM


I have an Epiphone with a bolt-on neck.

There was a lot of up bow in the neck and the truss rod nut didn't seem to want to tighten. I removed it, cleaned the internal threads with steel wool (wrapped around a drill bit and screwed through, multiple times) then lubricated it with grease. It then worked fine and with some judicious tightening, I was able to get the neck relief down to a couple of thousandths. It had been about 0.025", much too much.

The action at the 12th fret was too high. I made a tapered shim to go between the neck and the block that it bolts to. It is about 1/16th of an inch thick at the bridge end tapering to almost zero at the headstock end. This brought the action down considerably and, with a tweak to the adjustable bridge, I can dial it in to whatever I want. You can use some geometry to figure out how thick to make it or you could stack up some strips of cut up credit card or something at the bridge end, reassemble, put a string on, and see where you are. It might take a few iterations. I think some people just leave the plastic shims at one end and call it good enough. It is probably better to make a tapered shim that fills the whole pocket.

None of this was difficult, it just takes a little patience. Good luck and I hope it turns out well.

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