String height problem

[Lespaul_matt]

Hey Guys,

Having an issue with my latest build.

It has the 720 MOD done to the neck pocket,

So I am trying to get the strings to sit on the fret board properly but the bridge saddles are out of adjustment, it is a american standard fixed bridge, made by Callaham..

The Luthier putting it together says it needs a neck shim for it too work but, surely not.

Can anyone please help???

 

[Lespaul_matt]

Another pic of the bridge

 

[rolloman]

Is the neck pocket .720 from front to back like it should be with a 720 MOD? Is it a stock neck and not one that has a thinner heel on it? If so then I would say a 720 MOD is not a very good MOD at all, and probably gonna require a shim. Your trem and saddles I don't believe are the problem. Doe's anyone know if modern type saddles will lower the strings any from the vintage type?

 

[AirCap]

OK, I'll bite. WTH is a 720 mod?

 

[Lespaul_matt]

It has a deeper cut on the neck pocket so the neck sits deeper and I guess flatter. But, I wouldn’t think you can’t use a regular hardtail bridge with it. Now it looks like it has to be shimmed up which I don’t want to do.

 

[Verne Bunsen]

Check the neck pocket. If there is a lip of finish acumulated on the front edge then it will throw the neck geometry off, acting like a “reverse shim”.

This is from a Mustang I built a few years ago. It suffered from the same issue. Before:

After:

I use self-adhesive sand paper on a machinists rule, inward strokes only to avoid chipping the finish.

 

[Lespaul_matt]

It’s actually like the neck pocket is too deep. It’s the height from the bridge that’s the problem. We can’t get it low enough.

 

[stratamania]

OK, I'll bite. WTH is a 720 mod?

Detailed towards the bottom of this page...

http://www.warmoth.com/Guitar/Bodies/Options/GuitarNeckPocket.aspx

None of us can see what is going on with the guitar overall other than the action is not low enough and the bridge won't go lower.

The first course of action would be to take the neck off and check that the neck pocket rout is as specified. 

 

[Cagey]

It’s actually like the neck pocket is too deep. It’s the height from the bridge that’s the problem. We can’t get it low enough.

Well, it's actually nearly 1/8" too deep now. That's what the 720 mod does. Normally, a Fender-spec neck pocket is .625" deep. The mod lowers it .095", and adds a slight angle so the strings still rise to the bridge. Unless your bridge is very short, the strings are going to sit high on the fretboard. Your tech is right - you need to tilt the neck back at the headstock a bit to bring the strings down.

I'm surprised that bridge is too tall. The motivation for the 720 mod is to compensate for the gap that normally exists under the fretboard extension to allow for the thickness of a pickguard by eliminating it. On a Strat, more often than not there's a vibrato bridge installed that's very much like the hardtail you have, but usually ends up sitting even taller. This leads me to suspect there's no angle on that pocket. That's what I'd measure for, if I wanted to know for sure what was causing this.

Regardless, you're still going to need a shim. That's not the compromise it once was - there are some nice hardwood shims available now at various angles that cover the entire pocket floor, so you don't lose the neck/body coupling you used to lose when just jamming a wad of something in the pocket to tilt the neck.

 

[Lespaul_matt]

Okay thanks for that. To be honest I’m not really happy about the fact I have to use a shim.

I recently this year did a jazzmaster, rear route, it has the 720 mod selected also, used a hipshot bridge on that one and it was absolutely person, saddles set up at half height adjustment.

I’ve emailed warmoth to figure out what I need to check if something has gone wrong in the build process.

 

[Cagey]

Just lay a straightedge along the centerline of the body so that it overhands the neck pocket, then measure the depth between the straightedge and the floor of the pocket closest to the body, then farthest from the body. The far point should be slightly deeper, which would have the effect of tilting the headstock back.

They do that stuff with a CNC machine, so it seems unlikely to be missing the angle. I doubt it's an added step. But, who knows?

Another thing you might want to check is that the neck is being pulled in tight to the pocket floor - no gap between the neck heel and body. Warmoth cuts everything very exact, and the pockets get cut to tolerances so close you can often just press the neck in place and it'll be tight enough to lift the body.

 

[Verne Bunsen]

I still encourage you to give thought to my post above. If there is an accumulation of finish on the front of the neck pocket it will impact the geometry of the neck, causing the strings to sit high to the point that you cannot compensate with saddle height. Removing it will allow the headstock end to set back at the proper angle, lowering the overall string height the same way a shim would. I have encountered this problem and solution before with bodies from Warmoth and elsewhere. It is at least worth investigating before just installing a shim.

 

[Cagey]

Good point. I forgot about that one. Enough of an edge there would tilt the headstock forward and cause the problem shown.

 

[rolloman]

@Cagey are you saying that the 720 MOD's supposed to angle the neck pocket by design, or may have by mistake?

Not quite sure what this from the site is really trying to say. Lol

Our "720 Mod" lowers the floor of a standard neck pocket from .0625" to .0720".  This effectively reduces the height of the gap between the body top and the bottom of the fretboard at the 22nd fret.

* Bodies that already require an angled neck pocket because of being a carved top or because of a particular bridge choice are NOT eligible for this additional modification.

 

[Cagey]

I reviewed the site explanation, and there is no mention of any angle on the 720 mod, so it seems I must have been mistaken. I was under the impression they put a degree or two of tilt in with that mod. I may call them to find out for sure, because it seems like a necessary thing. I just measured the fretboard extension on a neck I have loose here, and it's only .225" thick. Add .030" to .050" for frets, and you're only a smidge over 1/4". Add maybe another .050" to .075" for string clearance. So, with big frets and a generous action, you'd be right at .350" (and probably unhappy). I don't have a hardtail out handy here, but with the fretboard flush with and the neck parallel to the body, that would mean you'd need a pretty damn short bridge.

So, I looked up a hardtail Hipshot bridge, which is pretty short...

...and the minimum string clearance is .350", with all the saddles down as low as they'll go, which is impractical due to fretboard radius. So, we're back to needing some tilt in that pocket.

 

[rolloman]

Hey, I just looked and measured a new Hipshot hardtail bridge I bought but never used. They actually have an option for a .125 thickness base bridge which would lower it another .050".  I wonder if this would save him.

 

[Fat Pete]

Hey, I just looked and measured a new Hipshot hardtail bridge I bought but never used. They actually have an option for a .125 thickness base bridge which would lower it another .050".  I wonder if this would save him.

I was just about to post about this. I'm sure this has come up before and the thinner-baseplate Hipshot was mooted as a solution.

 

[Cagey]

Tough to say. He's got a lotta clearance going on there...

 

[rolloman]

Yeah he does. If he wants for about 3 bucks postage I could send him this bridge so he could make sure before purchasing one. Give me a hollar if you want.

 

[vetteman]

I ordered the tele thinline body in the butterscotch blonde as seen in the photo below with the .720 mod 'cause it seemed like a good idea.  Made sure there was no finish left on the pocket floor and still needed to create a level shim to raise the neck up and keep the saddles in the 'normal' part of the adjustment range.  Found a black plastic day planner cover to fabricate the shim from (quality tone plastic!) and it plays fine now.  I honestly can't think of a bridge with such limited range of adjustment to require the .720 mod, (assuming a standard Fender spec neck) and will steer clear of it in the future.  Best of luck with your project!  :doh: