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Jazzmaster string height woes

Posted: Mon Dec 02, 2019 4:31 pm
by adamrobertt
I just built a partsmaster from a Squier VMJM body and a Warmoth neck. The guitar is mostly great, sounds good, etc, but I can't quite get the action low enough without the strings fretting out past the 12th fret. I have a 1 degree maple shim in the pocket from StewMac... I also tried a 1/2 degree shim but it wasn't enough. I thought about stacking the shims, but when I mocked it up the neck angle seemed really insane and I assume it probably won't work how I want it to. Anyone have any ideas on how to fix it?

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 5:34 pm
by timtam
adamrobertt wrote:
Mon Dec 02, 2019 4:31 pm
I just built a partsmaster from a Squier VMJM body and a Warmoth neck. The guitar is mostly great, sounds good, etc, but I can't quite get the action low enough without the strings fretting out past the 12th fret. I have a 1 degree maple shim in the pocket from StewMac... I also tried a 1/2 degree shim but it wasn't enough. I thought about stacking the shims, but when I mocked it up the neck angle seemed really insane and I assume it probably won't work how I want it to. Anyone have any ideas on how to fix it?
What is the relief and radius ? If you have a long straight edge place it on the frets and see if there are any high or low frets / odd neck profile. By fretting out do you mean on bends only ?

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 5:38 pm
by adamrobertt
No it's happening even without bending the strings. The frets look level to me but I'll double check. The relief is very straight, I didn't measure it, but it's pretty close to totally straight with only slight relief, and the radius is 9.5"

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 5:49 pm
by Larry Mal
Yeah, get a fret rocker. Don't pay that price.

It's part of any guitar setup, chances are very good that you go for low action, everything seems OK, but you are getting fret buzz. You probably have high frets somewhere.

It's also possible that you have that Fender "hump" in the neck where it meets the body, but that usually takes decades for it to occur.

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 5:55 pm
by adamrobertt
I'm not really getting any buzz, just the notes above the 12th fret choke out. I checked them with a straight edge and the seem level, but I'm not an expert and I don't really have the proper tools tbh

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 6:33 pm
by Larry Mal
The straight edge won't have a sufficient fulcrum to be able to show you the fret rocking. Watch the video there, you'll see what I mean. You can buy a knock off on eBay for $10 and it'll last you forever.

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 7:10 pm
by andy_tchp
Or failing that use a bank/credit card as a makeshift fret rocker.

All frets 'look level' to the naked eye. A few thousandths of an inch is all it takes to create buzz/fretting out.

Definitely need to measure neck relief, too. Fender spec ~0.08"-.010" relief for 9.5" radius necks IIRC which is a good starting point.

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 8:10 pm
by timtam
The long straight edge (covering the whole neck) will give you an overall sense of fret and neck profile, as well as any frets that are atypical. The fret rocker comes next, but can sometimes be misleading.*

*eg a fret that rocks can seem 'high' when in fact the adjacent fret is low. If you look at all possible 3-fret high/low fret combinations and whether a 3-fret rocker will rock / not rock when over them, there are roughly an equal number that it will get wrong when concluding whether a 'high middle fret' exists or not (false positive or false negative), as ones it will get right (true positive or true negative). So especially when people get into single-fret levelling, you can end up chasing your tail if if it's all based on just the fret rocker. If the rocker is all you have, just be careful to look for confirmation of a consistent pattern at adjacent frets (eg a low fret at one 'end' of the 3 will also rock when the rocker is centred over the next fret along .. as long as that fret is not low too !). If you're going to do a full-length fret levelling, then fortunately that will take care of any such idiosyncracies in the fret rocker findings.

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 9:16 pm
by marqueemoon
Are the nut slots cut deep enough? I’ve found that if strings are too high at the nut I overcompensate by dropping the bridge/saddles too low and it fucks everything up higher up the neck even if the relief is more or less right.

Re: Jazzmaster string height woes

Posted: Mon Dec 02, 2019 9:18 pm
by Larry Mal
Another good point right there.

Re: Jazzmaster string height woes

Posted: Wed Dec 11, 2019 12:07 am
by Subotnik
marqueemoon wrote:
Mon Dec 02, 2019 9:16 pm
Are the nut slots cut deep enough? I’ve found that if strings are too high at the nut I overcompensate by dropping the bridge/saddles too low and it fucks everything up higher up the neck even if the relief is more or less right.
What is the proper nut height?

I have similar questions about shims. I have a Johnny Marr Jag that I love, but the string action is a little high, even after checking neck relief and lowering the bridge. I mostly use the guitar for rhythm playing so I haven't been too bothered to fix it right away. Now I'm thinking of getting a StewMac shim, but this question about nut height is intriguing. I'm not sure anyone has ever worked on the nut on this guitar.

I'm also wondering if there are some ballpark guidelines for choosing a shim angle? I'd probably just buy the StewMac pack of three shims to make sure I have different options. After paying $10 for shipping I'd hate to have to make a second order.

Re: Jazzmaster string height woes

Posted: Wed Dec 11, 2019 1:23 am
by timtam
The string theoretically only has to clear the first fret by the barest of margins, as it's up hill to the bridge from there. I usually aim for around 0.3-0.4mm first fret action (about the same as relief); some people go lower, others higher. Best assessed with feeler gauges (cheap from the hardware store). It's best not to file the slots all the way down at first, as it's hard to go back if you go too far. If you get it near enough to the ballpark without any open string buzzing, go with that. It should then feel easier to fret on the low frets. If you don't want to buy nut files, the Zero Glide zero fret is another option.

Stewmac shims have a taper (how much they rise over their 76.1mm length) and an offset (base thickness) ....
0.25-degree shim tapers from 0.030" to 0.019" (0.76mm to 0.48mm) .. taper .28mm ... offset 0.48mm
0.5-degree shim tapers from 0.028" to 0.008" (0.71mm to 0.20mm) ... taper .51mm ... offset 0.20mm
1-degree shim tapers from 0.060" to 0.010" (1.52mm to 0.25mm) ... taper 1.27mm ... offset 0.25mm
(subject to manufacturing variation .. don't expect the exact angle, taper, or offset)

You can do the trigonometry to estimate for each shim approx how much a bridge at a given distance from the bottom of the pocket will be raised by each shim, to get the same action (and therefore how much bridge adjustment scope you will get back to lower the bride to the action you really want). But in practice I think the 0.5 and 1.0 deg shims are the most likely to be useful.

Note that the Marr supposedly already has a machined angled pocket of ~1deg. So only add a shim if the bridge is as low as it will go, the relief is good, and yet the action is still too high.

Re: Jazzmaster string height woes

Posted: Sat Dec 14, 2019 1:25 pm
by ChrisDesign
Definitely do a fret dress; it works wonders. Genders commonly use shims, even when they claim they don’t. Gibson, of course, angle their necks back at considerabe angles. Working in a 2 degree shim is fine.

Re: Jazzmaster string height woes

Posted: Sat Dec 14, 2019 6:09 pm
by adamrobertt
Thanks for all the replies everyone. I ended up fixing the problem by adjusting the truss rod quite a bit. Turns out Warmoth sends their necks with the rod totally loose, and I was way underestimating the amount of adjustment needed since I was just doing it by eye.

I bought some feeler gauges and brought the relief down to spec (.010'' at the 8th fret, capo on 1) and now the guitar plays REALLY well and the fretting out issue is gone. Phew!

Re: Jazzmaster string height woes

Posted: Mon Dec 16, 2019 8:37 pm
by ChrisDesign
adamrobertt wrote:
Sat Dec 14, 2019 6:09 pm
Thanks for all the replies everyone. I ended up fixing the problem by adjusting the truss rod quite a bit. Turns out Warmoth sends their necks with the rod totally loose, and I was way underestimating the amount of adjustment needed since I was just doing it by eye.

I bought some feeler gauges and brought the relief down to spec (.010'' at the 8th fret, capo on 1) and now the guitar plays REALLY well and the fretting out issue is gone. Phew!
Glad to help 👌🏻