Setting correct intonation in an Epiphone Casino

[steve barton]

Hi 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. My understanding is that the scale length is measured from the nut to where the string sits on the saddle. Please tell me if this is not correct.

According to most web sites, the scale length on a Casino is meant to be 628mm (24.75 inches). On my guitar 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 about 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.

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

Any help to get my guitar sounding as beautiful as it looks would be appreciated.

[demonx]

First of all, before we all start posting a million different ways to cut up the guitar and do this and that, lets work out how you're checking it first. Being this is your first post and your profile isn't filled out, I don't know if you're a 10yo kid or someone who's been playing guitar for 30 years.

So, how are you testing the intonation? Please describe in detail and we'll take it from there.

I have a $140 sabian tuner here that I have in the workshop for quick tuneups but I don't trust it for intonation, then I have a much more expensive tuner here in the office that is very accurate that I use for intonation. A tuner can make a big difference.

I always use the bridge pickup as there is less vibration closer to the bridge as the strings are anchored at the saddles. It gives more accurate intonation reading.

Sometimes, with TOM bridges, you can gain extra distance by flipping the saddle backwards to the way it's installed, often incorrectly. I had to do this recently on a customers LP copy. The saddles were in backwards.

[luke_lee]

Yes, the scale length is from the nut to the brake angle at the bridge. It will need compensation added to the scale length.

Try moving the breaking point back making the scale longer.

I would not modify the guitar, if you don't have any luck you should be able to get a replacement bridge with more adjustment.

Luke

[steve barton]

First of all, before we all start posting a million different ways to cut up the guitar and do this and that, lets work out how you're checking it first. Being this is your first post and your profile isn't filled out, I don't know if you're a 10yo kid or someone who's been playing guitar for 30 years.

So, how are you testing the intonation? Please describe in detail and we'll take it from there.

I have a $140 sabian tuner here that I have in the workshop for quick tuneups but I don't trust it for intonation, then I have a much more expensive tuner here in the office that is very accurate that I use for intonation. A tuner can make a big difference.

I always use the bridge pickup as there is less vibration closer to the bridge as the strings are anchored at the saddles. It gives more accurate intonation reading.

Sometimes, with TOM bridges, you can gain extra distance by flipping the saddle backwards to the way it's installed, often incorrectly. I had to do this recently on a customers LP copy. The saddles were in backwards.

Hi Allan,

Thanks for your prompt response to my post. I agree with you that any destructive work on the guitar is an absolute last resort which is why I am so grateful for opinions of experienced people like yourself. By way of introduction I am in my late 50s and have been playing guitar since the early 70s. I play mostly blues and 60s rock. I have developed an interest in luthiering and to date have built a "Tele" style electric and an acoustic, both under the supervision of top luthiers. So I guess I am a beginner in this area but certainly have a reasonable knowledge of guitars and what makes them tick.
My perception of why the intonation is out comes from the fact that playing anything above the 9 or 10 fret is out of tune. Particularly sounds ugly playing chords or scales up the neck. To try and set the intonation I measured from the inside edge of the nut to the crown of the 12 Fret. That gave me a measurement of 314mm. I then measured from the crown of the 12 Fret to the bridge and 314mm took me exactly to the outside edge of the bridge. That gives me a distance that is exactly what the scale length is meant to be. However the saddle sits back from the edge of the bridge and when adjusted as far forward as possible is about 5mm from the edge. This would mean the distance from the crown of the 12 fret to the point where the string meets the bridge is about 319mm which obviously gives me an incorrect scale length. When the saddle is moved as far forward as possible the guitar at the 12 fret is about a semitone out. I am measuring this with a number of different tuners and have tried them plugged in and just acoustically. I have also used tuners built into my boss multi-effects pedal. All give very similar results.

Thanks for your response and your thoughts.

[steve barton]

Yes, the scale length is from the nut to the brake angle at the bridge. It will need compensation added to the scale length.

Try moving the breaking point back making the scale longer.

I would not modify the guitar, if you don't have any luck you should be able to get a replacement bridge with more adjustment.

Luke

Thanks Luke
Appreciate all the feedback and will consider it all before doing anything I may regret later like drilling my guitar. Hopefully Epiphone may eventually reply and give me the official view.

[kiwigeo]

To try and set the intonation I measured from the inside edge of the nut to the crown of the 12 Fret. That gave me a measurement of 314mm. I then measured from the crown of the 12 Fret to the bridge and 314mm took me exactly to the outside edge of the bridge. That gives me a distance that is exactly what the scale length is meant to be. However the saddle sits back from the edge of the bridge and when adjusted as far forward as possible is about 5mm from the edge. This would mean the distance from the crown of the 12 fret to the point where the string meets the bridge is about 319mm which obviously gives me an incorrect scale length. When the saddle is moved as far forward as possible the guitar at the 12 fret is about a semitone out. I am measuring this with a number of different tuners and have tried them plugged in and just acoustically. I have also used tuners built into my boss multi-effects pedal. All give very similar results.

Thanks for your response and your thoughts.

On a guitar that doesn't have any compensation dialed in at the nut (ie compensated at saddle only), the nut to 12th fret distance is always going to be half the theoretical scale length (314mm in your case). If compensation has been applied at the saddle then the 12th fret to saddle break distance for each string will normally be greater than 1/2 theoretical scale length by varying amounts depending on string (more compensation generally required for thicker strings).

You say 12th fret to saddle break is 319mm....ie 1/2 theoretical scale length (314mm) plus an extra 5mm. Is this on ALL strings or are you talking about one string? If all the strings are 5mm back from theoretical scale length then something screwy is going on. If correctly compensated I'd expect the 12th fret to saddle break distance to be different for each string....usually increasing with string guage.

Can you supply a picture of the bridge?

For an excellent explanation of intonation I'd recommend Gore and Gilet's excellent Book set....http://www.goreguitars.com.au/main/page ... rview.html

[Nick]

For an excellent explanation of intonation I'd recommend Gore and Gilet's excellent Book set....http://www.goreguitars.com.au/main/page ... rview.html

Quite an expensive way just to fix this one problem

You've measured things with a rule (and from what you say, it sounds like something funky is going on) but have you done the 12th fret fretted against it's harmonic test first? that's always my first point of elimination when trying to solve issues. Next, go to Stewmac's fret calculator, fill in the relevant details for your guitar (but be aware Gibson's/Epiphone 24 3/4" scale actually isn't and usually involves 5 possibilities depending on year of manufacture!) then check your fret spacings against the ones Stewmac gives, I can't imagine a factory guitar being wrong but we all know what assumption is the mother of! It never hurts to check and eliminate. Also have the saddles been 'switched' around with the longer 'ramp' facing forward, these can be taken out & turned about 180 degrees which would offset the break point toward the tail piece and thus away from the 'ideal' intonation point.
As Allan said, eliminate the simple things first before you start ripping the guitar apart. Sometimes even something as simple as a new set of strings can cure a problem, we assume because they came out of a freshly minted plastic packet that they have got to be good but it is possible to find a dud set, one that slipped past quality control.
You still may never have to take a tool to the guitar if everything above checks out ok, there are aftermarket parts that can help get around problems. Stewmac again, have a locking roller bridge that can give you that little bit extra as it can be moved backwards and forwards on the posts.

[jeffhigh]

Whereabouts on the bridge are you measuring to. (high E low E or between D and G)
The bridge appears from photos to be sloped.

[demonx]

Let's back track a bit first

You keep talking about measurements, but s couple of the others are hinting at what I'm about to say, it doesn't sound like you've actually tested the intonation yet.

Measuring as you've described is not testing the intonation. It also does not allow for compensation and not all scale lengths use the same amount of compensation.

Now, let's break it down to the absolute basics and start from scratch.

Plug into your best electronic tuner and tune the guitar.

Once tuned, fret the 12th fret. Don't measure. No measuring takes place with intonating an electric. The manufacturer has already set the bridge position and if it's a real epiphone I'd assume it's not going to be wrong. A Chinese knockoff not so sure.

So, tune the guitar as perfect as possible, select the bridge pickup on the toggle switch, fret the 12th fret, plucking with a plectrum at a constant rate with about one gentle pluck per second so you are creating a smooth electronic pulse to the tuner. If the tuner bounces forward, adjust the saddle forward. If the tuner bounces back, adjust the saddle back.

This is how to adjust the intonation.

If after doing this you run out of adjustment, we'll look at that when the time comes.

[jeffhigh]

If the tuner bounces forward, adjust the saddle forward. If the tuner bounces back, adjust the saddle back.
.

Just to clarify, since the terms forward and back can be ambiguous.
When plucking at the fretted 12th, after tuning the open
-If the tuner reads High then the saddle need to move towards the tail
If the tuner reads low then the saddle need to move towards the nut

[kiwigeo]

For an excellent explanation of intonation I'd recommend Gore and Gilet's excellent Book set....http://www.goreguitars.com.au/main/page ... rview.html

Quite an expensive way just to fix this one problem

Maybe so.....but the books give one the whole picture on the reasons for intonation issues with fretted instruments.

Note also that as the Official Gore Recruiting Officer for the Gore Army the post was a matter of duty

I agree that OP seems to have not actually done the normal intonation tests.

[old_picker]

Not the first gibson or epi i've seen that has the bridge position slightly off. Usually you can get it close enough and when explaining the implications of moving the bridge the owner will usually opt for close enough.

A photo or two of the guitar its model number etc is always very helpful .
Allan's advice on ensuring the intonation is out using a tuner rather than a ruler is gold.

flipping the saddles around can give you a bit.
lifiting or lowering the action can give a bit more

If you cant get it right after tryng the above then the shifting of the posts could be considered

if it is a pre gibson era epi set it as well as you can and leave it alone

[jeffhigh]

The other thing that needs mentioning is that checking the intonation should be one of the last items done in a setup, after adjusting relief. nut slots and bridge height.

[rocket]

I'm speechless,, except to say this shit shouldn't happen!! even low end instruments should at least have the numbers right!!
Rod.