MIMF

Hi fellow luthiers
I have an Epiphone Casino which I cannot intonate correctly. I suspect the bridge has been put in the wrong place when fitted in the factory but need the collective knowledge of the forum to confirm.

I understand the scale length is meant to be 628mm (24.75 inches). The distance from the nut to the centre of the 12th fret is 314mm which is exactly the same as the distance from the 12th fret to the front of the bridge. Even if I set the saddle pieces as far forward as they can go this means the distance to where the string sits on the saddle is another 5mm. Of course setting the saddle this far forward wont put the guitar in tune.

If I am correct in that the bridge is too far back then I have a couple of questions about moving it.

1. Does the bridge have some sort of support block under the top which would make it difficult to reposition.
2. How could I repair the two holes in the top that would be there if I moved the bridge.

Great guitar with a really nice finish so don't want to ruin it but I cant play it up the neck. Have written to Epiphone but no response.

http://www.stewmac.com/How-To/Trade_Sec ... _tune.html

You should look inside the guitar to see what reinforcement is there. You probably have enough room to move the bridge. Sometimes you can increase the amount of correction by reversing the saddles, but I'll bet you have indeed run out of room. It will be pretty tricky to touch up that finish, but check out the stew mac video

Thanks Joshua,
I appreciate you taking the time to reply
I wont do anything until I review all the comments and feedback and hopefully get a reply from Epiphone support. Its a bit hard to look inside given its such a thin body. Just thought someone may have already ripped one apart and know the answer. Its a great guitar and I really would like to get it fixed so I can use the entire neck not just the lower half.
Steve

Unless I am misunderstanding (quite possible), I don't think you have a problem with your bridge placement. In order to intonate correctly the scale needs to be slightly longer than the nominal scale length. That means that each string will need to be slightly longer than the 628 mm. You will adjust the individual saddles to where they need to be for each string. If the fretted notes are going sharp up the neck move the saddle back. It they are flat, you have them too far back and need to bring them forward.

It could be that Epiphone put the bridge in the wrong place but that would not be the first thing I would suspect. Tune each string to proper pitch and move the saddle until the fretted 12th fret matches the 12th fret harmonic. Keep going until you get it as close as you can. You will never get it to intonate perfectly; that is just the reality of fretted instruments. Before you do all this, make sure you have the strings you intend to use gong forward. Different string gauges require different intonation adjustments. Also, make sure you have the set up you want (nut slots cut to proper depth, saddle height, neck relief. . .) before you set the intonation.

If this is a brand new guitar that has never had its initial set-up and you don't know how to do it yourself, consider taking it to a luthier for a set-up. He or she should be able to make sure the neck and fret plane are adjusted properly, fit the nut slots and set the action and intonation for you. Most people don't realize that guitars don't come from the factory with complete set-up (for various reasons); paying for a good set up (or doing yourself) is something that should be factored in when making the purchase.

Bryan has a good point here. Are the fretted notes sharp or are they flat? Intonation is one the the more confusing aspects of lutherie and every time I deal with it I have to stop and think about what the symptoms are and what they mean.

At the risk of redundancy, set the saddle all the way forward. If the 12th fretted note is sharp to the harmonic, move the saddle back until they are the same. If the fretted note is flat (with the saddle all the way forward) then you've got a problem.

If the guitar is covered under a warranty the distributor should either repair or replace it. It's not likely a repair can be made invisible, as it would require the bridge mounting posts be removed, the holes plugged, and new holes drilled in the correct location. In such cases I suggest you be the squeaky wheel. Be nice but be firm, you didn't intend to buy a flawed instrument.

Like the others have stated, it's fixable but the repair likely won't be invisible. But you shouldn't have to fix a factory screw-up in the first place.

I would also recommend you return it and get another one. You said Epiphone didn't respond, so if you bought it from a dealer I would start there. Make them get in touch with Epiphone or whoever and get it taken care of. It's faulty and unplayable, which you didn't realize until you got it home. What else is a consumer to do in such a case? Don't take "no response" to an email deter you from getting what you pay for. I wouldn't stop short of getting a new guitar personally.

If indeed the bridge is too far back to allow proper intonation, you can find replacement bridges that allow for more adjustment range. One example is the Wilkinson roller bridge which has oblong post mounting holes and grub screws. There are other bridges that simply have more saddle travel.

The other option is to use thicker strings, which would need more compensation.

Tune-O-Matic in the wrong place? Check out this StewMac video. This is a really slick solution.
http://www.stewmac.com/How-To/Trade_Sec ... _tune.html

Any update on this? I'm just curious.

Hard to believe that this topic has gone this far without naming and fully describing the term "compensation". That is the amount of extra string length added onto the scale to get the strings intonated correctly. Compensation will vary with the different strings, which is why most saddles are slanted. If the front of the bridge is set at the exact scale length (the same distance from the 12th fret as the nut to 12th fret distance) then it is probably pretty close. Do you know how to check the intonation using a tuner? There has been no mention that this basic step has even been performed.

Barry. I thought I did just that on my first post (8/13). Perhaps I didn't communicate it well enough; I have that problem sometimes and text format compounds my shortcoming. I was trying to describe how to set up and check the intonation then adjust the compensation for each saddle. I suspect that the bridge is not in the incorrect position but that the saddles have been moved too far forward attempting to match the scale difference from saddle to 12 to the nut to 12. That (I suspect) has resulted in not enough compensation. Now the intonation is off but the opposite direction one might assume (if one doesn't know that the actual vibrating string length need to be slightly longer than the nominal scale length). Further, any set-up issues need to be sorted before compensation/intonation get set.

I don't know if the OP knows this or not, but I wanted to make it clear just in case, before the bridge was moved to fix a problem that may not exist.

All that said, it is entirely possible the bridge did get positioned properly.

Bryan, you are right, most of the information was there. Only needed the compensation term.

Gotcha, I tend to lump the terms together when I know I shouldn't be. I know intonation refers to how well the frets play in tune as you go up the neck and that compensation is the added length a string gets to achive the best possible intonation. But, I tend to say things like setting the intonation when I really mean adjusting the compensation. I guess as an acoustic only guy, I tend to think of compensation as something you "build in" during the process of locating the bridge. Further changes of the compensation (filing the saddle. . .) happen when you check the intonation and I lump it in with that process. . .

But yes, an important clarification when discussing/troubleshooting cases like this.