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Intonation Question


psiico
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Hi all, I'm new here so bear with me. I've been playing for 20 years or so but had a break of 12 years where I didn't own a guitar and rarely played, now I'm getting back into it, don't know what the hell I was thinking when I stopped. I've got a beat up (very beat up) Epiphone piece of crap I got from a friend for literally next to nothing that needs a lot of work. I couldn't tell you what it is because it doesn't have a name, Epiphone sent me an email telling me what it was called and it was basically just a number. Really it's little better then a Harmony Sears guitar, I used to have one of those (my first guitar) so I know how bad they are, this one is better then that but not by much. The Epiphone retailed for $80 US when new many years ago.

It's got dents and dings galore and had a nasty bow in the neck when I got it. Unpotted soapbar pickups, some strange tremolo style bridge that I've never seen before, dented frets and cheap-o tuners. Sounds like a perfect "project guitar" to me! So here's my long term plan. I'll get to the intonation question, trust me.

First, replace the body. I've always wanted to build a guitar but never had the nerve to do it. I figure here's a good excuse to start small and I won't worry too much if I make a mess of things. The body now isn't plywood, but it's nothing fancy either, also, it's thin, about 1.25 -1.5 inches, I didn't measure it. I figure I'll make a new body from a blank closer to 1.75-2 inches thick.

After that I'll sand and refinish the neck hopefully removing the majority of the dings and dents and then refret it. Replace some hardware, pot the pickups and hopefully have a half decent guitar. Maybe then I'll be ready (or prove to myself that I'm not) to try building one from scratch.

Here's my question, I fixed the bow no problem and then proceded to set the intonation but I can't, it seems the bridge is mounted too far forward by 1/8-1/4 of an inch or so. Could this be because of the string gauge I used? I used .009-.042 strings. I haven't setup a guitar in years, this is my first guitar I've owned in 12 years so I'm a little rusty and can't remember if string gauge matters that much. Would heavier strings make enough difference to set it up right? Or would they make any difference at all? Back when I used to play I always used .009's so I went with those again although I won't mind going up a size or two, none of that SRV .013's me me though!

Thanks for your help.

Edited in:

I dug through my emails, it's an 1802-T. Here's some of what Epiphone sent me. The guitar I have is missing the tremolo arm and the metal cover that sits over the backplate of the bridge.

1802t25tz.jpg

Edited by psiico
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A "hand vibrola"!! That's classy. :D

You might be screwed. String guage matters a bit for how well your guitar stays in tune at the lower frets, but for purely setting up intonation at the 12th fret, which is the 'halfway point', the guage factor is at its minimal. The thicker your strings are, the more you'll have to 'compensate'.

BUT, if your bridge is literally mounted too far forward, in a way that might be the problem. The bridge itself was already compensating for heavier string guages, and now that you have lighter strings, it doesn't need as much compensation to intonate properly.

If your saddle is as far forward as it will go and it still won't intonate, you might be S.O.L. without physical modification to the guitar.

Greg

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If you're willing to do a refret, then why not just go ahead and make the neck too?

Fretting seems to be the most difficult part (to me --it's what's keeping me from making my own).

There's a lot of work involved just in making a body, it makes no sense to spend all that time just for a neck you don't like and can't trust.

In the meantime, go get yourself a decent guitar to play. No point in building a guitar if you don't have one to play while you're waiting for the finish to dry...

Oh yeah, and you could look into selling this Epiphone as 'vintage'...

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it seems the bridge is mounted too far forward by 1/8-1/4 of an inch or so

I’m curious. On what are you basing this statement? Have you measured the distance between the nut and fret 12 and compared to the distance between fret 12 and bridge. If the fret 12 to bridge distance is shorter, or perfectly equal to the first measurement, then you are in trouble. Having that said, I really doubt that the quality control of Epiphone would miss THAT big fault. I think that the problem might be another.

If the problem is that the saddles in the bridge is adjusted as far back as they go, and your intonation on fret 12 is still sharp, it can be a completely different problem. You write that the guitar has a “nasty bow”. If this means that the string height is extremely high, that will also affect the intonation. Intonation is used to compensate for the extra tension on the strings caused by pressing it down to the frets, stretching the string slightly. Higher strings means that the saddles need to be adjusted further back. Very worn frets might also cause offsets in the tuning. A string is supposed to rest on the top of the fret. If the fret is worn fret the break off point is moved towards the bridge. This also means that the intonation will be off. If you still have the old strings on that guitar you will also have problems with intonation. We have several treads in here describing the problems with intonation a guitar with old strings on.

So, before you start to adjust intonation, you need to adjust the truss rod, adjust string height, level the frets, and put on new strings. There in NO WAY that you can intonate before you have done those things.

But if the length from fret 12 to the bridge is shorter than from the nut to fret 12 you have to move the bridge.

Edited by SwedishLuthier
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Nicely put SwedishLuthier, intonation is the last step in a setup, not the first. Old strings can make a guitar non-intonatable, so try a new set for sure. There are basic steps in setting up a guitar properly. Here's the steps I use.

1. Using a long straightedge, hold it in the center of the neck, and check for relief. Measure the gap between the top of the fret and bottom of staightedge with feeler guages at around the 7th fret or wherever the gap is widest. If it's over .015" of relief then you've got too much, and you should adjust the truss rod slowly 1/8" a turn at a time until you have somewhere between .0" to .012". I try for .006" of relief most of the time.

2. Retune the guitar and capo the 1st fret to eliminate the nut.

3. Set the action at the 12th fret with a 6" steel ruler. A measurement of 4/64" is a great starting point, and by setting each string this way, your bridge will be adjusted to the correct radius by default. You can always lower your action later, but that will get you in the ballpark.

4. Take the capo off the first fret. Slot the big E string so that the gap when measured with a feeler guage is .020" between the top of the first fret and bottom of E string. The little E string can be slotted deeper so that you have .016" or less gap at the first fret. The other strings will be gradually inbetween those two strings. This can be lowered later also, to make the guitar play better, since this is rather high measurements for great action in the lower fret regions.

5. Finally, intonate.

Good luck

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Thanks for the replies guys. The first thing I did was fix the bow with a truss rod adjustment. I read somewhere that if you fret the first and last frets the gap at the 7th fret should be somewhere between 1 and 3 playing cards in height so I set it at just over 1. I also put a straight edge along the neck and it was the same fit.

I can't do much about leveling the frets right now, just don't have the knowledge or the tools. It's the first 5 that are dented and they are dented from playing. Visually the 12th fret looks fine although I assume that really doesn't mean much. A couple of the dented frets are pretty bad, leveling them might make the frets too small, likely it would be too small for my taste if not for playing in general.

I set the action to what was comfortable and doesn't buzz. It buzzes slightly when I play really hard with open strings in a chord but it's not noticeable through an amp, just when not plugged in. I don't know what the string height is but it works for me, it's pretty low.

Yes, they are brand new strings. The problem I have is the saddles are adjusted as far back as they can go and the notes are still sharp. I'm guessing how much the bridge might be off based on how far I had to move them to get what I have now and what I figure it would take to get it intonated properly. Looks like 1/8" or more.

I also have a problem accepting Epiphone made a mistake, that's why I'm here! :D I figured you guys would know more about this then me. It is a cheap guitar, what was the quality control like on such a cheap instrument?

I was going to make a new body for it for fun and practice so I was asking about this intonation problem wondering if I should mount the bridge where it is again or mount it further back. I likely won't even use that bridge in the new body anyway but I still need to know where to put the bridge centerline. Sorry if that's not the correct terminology, like I said, I'm a newb here, lol.

Is there a formula for this? Can I measure the frets and work out where the bridge should be? It's usually done the other way, right? First figure out where the bridge goes (ie. scale length) then work out how to space the frets. First I guess I'll measure from the nut to 12th then 12th to bridge, I never even though of that. I knew coming here was a good idea. :D

Someone mentioned buy a new neck. Eventually I might have to, lol, I plan to refret this one as a way to learn how. If I wreck this one it's no big deal because it's basically wrecked now anyway. I'm going to pick up another guitar just to bang away on while I work on this one. I'm not expecting to have an awesome guitar when I'm done messing with it, I just want to learn something about building before I try one from scratch. I don't plan to start for months yet, I like to research a lot before I do anything.

Or is what I'm considering sacrilege? I don't consider this a vintage guitar even though it's old because it's both cheap and uninteresting. In another of my hobbies there's a segment of people that frown upon modifying certain old equipment just because it's old and no longer being made. I wouldn't refret a 57' Strat neck as my first try and I wouldn't build a body replacement for and old Les Paul either. This thing on the other hand .... Opinions?

Thanks again.

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I think you are doing exactly the right thing. Go ahead and practice on something you don't care that much about before working on the expensive instruments. Learn as much as you can. I don't think anyone is going to mind modifications to this guitar.

Definitely measure the location of the bridge now. If the bridge location is correct, you need to find another explanation for things being off. I seriously doubt the bridge was mislocated that much from the factory (that's a big error, even for a cheap guitar). But this guitar may not have all original equipment either. Perhaps the bridge was replaced at some point and the saddle location isn't correct, or some other modification was made.

But when you build your new body, be sure to place the bridge in the correct location at that time ... forget about where it is located on the old body. With your scale length and bridge dimensions known, you can figure out exactly where the bridge needs to be.

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Okay, I measured it. I couldn't find my regular tape measure though, I used a tailer's measure, lol. Metric only. It's 31.35 cm (using my uber precision eyeballs) from the neck side of the nut to the middle of the 12th fret. From the 12th fret to the middle of the saddle for the low E (the furthest backed off saddle) it's 31.9 cm. The middle of the range of travel for the saddles looks to be about 31.4 cm.

You guys are the experts, is this right or should I be building my new body with the bridge set back a tad further?

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I like the neck, it's the worn frets I don't like, lol. I picked up a piece of crap Yamaha today as a second guitar so I'll have something to play in the meantime. I still don't plan to start this project for a while though.

According to that chart the bridge is in the right place. I guess worn frets are the problem then with the intonation.

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I just thought of something:

How are the saddles in the bridge shaped? Most Tune-o-matic style bridges have saddles that are reversible. The top of the saddle is angled forward or backwards. Is this the case with the bridge on this guitar? If so, and the saddles are pointing towards the neck it is possible to reverse them and by doing so get a little more adjustment in the bridge, maybe enough to get it to work.

Judging from your measurements (and the rest of your description) the bridge is probably a little offset. 4mm of backward travel in the saddles is a tad to little, and can give you this problem. There are a few more things that you can check before going any further with the new body. Not that I consider this guitar the Holy Grail, but I would love to be able to help save this old guitar…

When placing the bridge I usually start with the saddles somewhere between the middle and the most forward position. Then I place the bridge so that the saddles are at the theoretical correct position, i.e. the distance from fret 12 to the nut is equal to the distance from fret 12 to the saddles in the bridge.

Another thought:

Have you, using the StewMac calculator, checked the distance from the nut to the FIRST fret? If the nut is out of place (to far away, leaning away and so on) you can get the same problem. You tune up and compare to the note at fret 12 and it will be sharp.

One other thing that can cause this is if the slots in the nut are slightly rounded. If the strings doesn’t have a clean break off point in the nuts fret board edge they will vibrate with a length that is too long and…just look above.

A last suggestion:

If nothing else works, it is possible to move the neck slightly. Remove the neck, plug the holes and drill new ones that get the neck slightly further away. Cut a new pick guard to cover the gap. Not the world’s finest repair but it will work.

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Halfway between fully-forward and fully-back is too much, IMO. When compensating during the intonation process, a saddle will NEVER need to be closer than its scale length, it will only ever need to be longer (ie. further back).

Give yourself a few mm of wiggle room to move the saddle forward just in case the actual mounting process goes wonky, but the further back you put the bridge to begin with, the more likely you'll get a properly-intonated low "E" string. I've had guitars in which I had to take out the spring behind the saddle and STILL could've used another millimetre or two of extra space.

Greg

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The bridge is made up of rollers, not wedges. You mean a Les Paul style bridge right? This one is nothing like that. I'll take pic when I get home from work tonight so you can see how it is. The problem might even be wear on the bridge saddles yet, they are plastic.

I didn't check that distance to the first fret, I'll add that to my list of things to do when I get home. The nut slots might be rounded, it's old enough. I'll have to look closer I guess.

I won't be moving the neck, the guitar will stay as is until I start building a new body for it. I have another guitar now anyway so it's no big deal. It's not like I'm recording or playing live or anything anyway, I went 12 years without a guitar, I have a lot to relearn. Comes back fast but boy am I sloppy when I pick up the speed on some things and because I used to be able to play them I find myself not having the patience to slow down until I can get in the groove again. Having a guitar that has bad intonation is not that big a deal with where I am in my playing. :D

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