Fret Rocker - How to Use?

[cap217]

I do setups but never touched fretwork or nuts. I dont want to either but I bought a stewmac fret rocker just because I was curious about some buzz on my collings. The issue is, how do you use this and is any amount of rocking acceptable?

- Does the neck need to be dead straight before you use this?
- With or without strings/tension?
- Is any rocking a bad thing or are there tolerances that are acceptable?
- Where should falloff start? I get rocking at the 11th fret on my collings too.


I ask because I have recently setup my guitars (collings d2h, bourgious om, j45 tv) to "correct" specs of .005", well I went to .006 and .007 on the J45. I used to do this more by feel and sight which was around .010" without knowing it. But I had some buzz in my collings and they told me to go to .005". That doesnt seem like a big change but its dramatic and the neck seems so straight now. But the buzz was still there. So I got this rocker to test frets. The collings has some rocking at the 3 and 5 fret with .006" relief and strings on. But I dont know if thats how I should be testing.

[blindboyjimi]

Here you go







As you can see 2 of 3 are using it without tension on the neck. I do it like Dan E since I bought the tool off him and under tension is what matters. But I use 0.005” as maximum relief.

[cap217]

Originally Posted by blindboyjimi

Here you go







As you can see 2 of 3 are using it without tension on the neck. I do it like Dan E since I bought the tool off him and under tension is what matters. But I use 0.005” as maximum relief.

This is whats confusing. Some with and some without tension.

.005" max? man, thats super straight. What is your action height? I go for 6/64 4/64.

[charles Tauber]

It isn’t that complicated.

For most players and listeners, The goal is to have the guitar play without buzzing. One potential cause of buzzing is uneven frets. If one or more strings buzz when fretted at one or more specific frets, a common cause of that is uneven frets - either a fret too high or too low relative to its neighbours.

If one has that situation, of buzzing while fretting at a specific fret, one doesn’t need a fret rocker to determine the problem: it is, in that circumstance, that either the fret above it is too high or the current fret too low. The buzzing does not occur when their is no tension on the strings, of course. Hence, it is the as-played condition that one is concerned with.

[SpruceTop]

Originally Posted by cap217

This is whats confusing. Some with and some without tension.

.005" max? man, thats super straight. What is your action height? I go for 6/64 4/64.

+1! I feel a neck relief of .005 inches, when the action-height at the E-6th string of 6/64ths inches (.094 inches), is the absolute minimum an acoustic guitar should be set at, especially one played with a flatpick. I like a minimum of .008 inches with .094 inch action height for flatpick usage with medium-gage strings and light-gage strings and I find it's still comfortable for fingerpicking.

[ManyMartinMan]

Originally Posted by cap217

I do setups but never touched fretwork or nuts. I dont want to either but I bought a stewmac fret rocker just because I was curious about some buzz on my collings. The issue is, how do you use this and is any amount of rocking acceptable? ....

Can't say. I drive down from the hills to my dude, drop of the guitar(s), and come back in a week to pick them up. He knows my play and how I want my guitars. Works like a charm.

[phavriluk]

We can get an awful lot of the good of a fret rocker by using whatever of the sides is appropriate to cover three frets. If it don't rock, move on to the next fret and try again (left, right, and center, too, no saying any one fret is on the same plane as a neighbor). Comments above describe what to do with an offending fret.

[AndrewG]

Wouldn't a short 6" steel rule do the same job? After all a 'fret rocker' is simply a straight edge. That said Stewmac do something called a 'Fret Kisser' which is a straight edge and fret leveling tool in one. Could be useful for home setups:

https://www.stewmac.com/Luthier_Tool...xoC6A8QAvD_BwE

[RickRS]

Originally Posted by AndrewG

Wouldn't a short 6" steel rule do the same job? After all a 'fret rocker' is simply a straight edge. That said Stewmac do something called a 'Fret Kisser' which is a straight edge and fret leveling tool in one. Could be useful for home setups:

https://www.stewmac.com/Luthier_Tool...xoC6A8QAvD_BwE

Video shows the tech checking with a Fret Rocker, then leveling with the Fret Kisser, and rechecking with the Fret Rocker. So it suggests the Kisser doesn't replace the Rocker, and you should get both to do the job. Anyone have experience with the two and know differently?

[DukeX]

Originally Posted by AndrewG

Wouldn't a short 6" steel rule do the same job? After all a 'fret rocker' is simply a straight edge...

Not quite, it's a combination of four straight edges of different lengths. As Dan explains, when checking for high frets you just want to span three frets (the middle fret being the one being checked). You can't do that with a 6" rule. Also, the Fret Rocker is "precision-machined for accuracy to .0015" per foot." No guarantees with most rules.

[mirwa]

A really good neck with sufficient strength to combat string tension can be checked for high frets without strings on.

Most necks bend a little or twist a smidge under string load, for this reason we traditionally check for high frets when the guitar is strung up, i always check any neck whilst it is under string tension.

Steve

[Howard Klepper]

Originally Posted by cap217

I do setups but never touched fretwork or nuts. I dont want to either but I bought a stewmac fret rocker just because I was curious about some buzz on my collings. The issue is, how do you use this and is any amount of rocking acceptable?

- Does the neck need to be dead straight before you use this?
- With or without strings/tension?
- Is any rocking a bad thing or are there tolerances that are acceptable?
- Where should falloff start? I get rocking at the 11th fret on my collings too.


I ask because I have recently setup my guitars (collings d2h, bourgious om, j45 tv) to "correct" specs of .005", well I went to .006 and .007 on the J45. I used to do this more by feel and sight which was around .010" without knowing it. But I had some buzz in my collings and they told me to go to .005". That doesnt seem like a big change but its dramatic and the neck seems so straight now. But the buzz was still there. So I got this rocker to test frets. The collings has some rocking at the 3 and 5 fret with .006" relief and strings on. But I dont know if thats how I should be testing.

What kind of buzz are you talking about? Where on the neck? Which strings? Picking gently? Or do you have to pick or strum hard to hear it?

I'm asking these questions because so far you have given no reason why you should be using the fret rocker tool. It is for locating single frets that are raised up from the fretboard. Because that is its only purpose, it does not make much difference whether the neck is under string tension or not when you use it.

A fret rocker will not substitute for the most useful straightedge to use when setting up a guitar, and that is a precise 12" one. And it surely won't substitute for a good understanding of neck and fret geometry. I get a sense from your question that you are bringing the wrong tool to a setup job.

BTW, .0015" over a foot is good enough for woodwork and just about good enough for fretwork, but it is not close to the accuracy of a good machinist's straightedge. I bought a fret rocker from StewMac several years ago. It was not flat--not even close--which made it useless. I returned it and instead got a good 3" knife edge straightedge on Ebay from a retired machinist for about the same price as the fretrocker.

[mirwa]

Originally Posted by cap217

I do setups but never touched fretwork or nuts.

A good setup always includes tweaking the nut/saddle/truss rod/polishing frets and or levelling any high frets

94 thou string clearance referenced in one of the posts is IMO too high.

My initial setup for an acoustic guitar is 4 thou relief, 80/60 at the 12th fret.

Steve

[murrmac123]

Originally Posted by Howard Klepper

I bought a fret rocker from StewMac several years ago. It was not flat--not even close--which made it useless. I returned it and instead got a good 3" knife edge straightedge on Ebay from a retired machinist for about the same price as the fretrocker.

Hi Howard, season's greetings from Scotland !

As ever, your posts are the epitome of sagacity, but you must forgive me if I have to take you to task regarding your reference to the "flatness " of the Stewmac fret rockers.

I spent (wasted) far too many years making the most accurate luthier tools available anywhere, including fret rockers, and although I took pains to make my rockers totally flat , I would suggest that absolute "flatness" is not really a huge concern.

What is critical is absolute "straightness" . The manufacturing process used by manufacturers, whether stamping, laser cutting or waterjetting, will never produce a perfectly "flat" fret rocker ( at least not at any economically viable price point) , but with adequate quality control, can certainly produce a "straight" fret rocker.

It may well be that the fret rocker you purchased from Stewmac was in fact not "straight" in addition to not being "flat", but in the general scheme of things, as long as the rocker is "straight" and as long as the operative has sufficient skill to hold the tool perpendicular to the fret, the "flatness" isn't a huge consideration.

All best wishes for a prosperous 2020 !

[Howard Klepper]

Murray, by 'not flat' I mean that the plate was warped. That made it impossible to place an edge on the frets and have the edge stay in the line of a string path. Even if an edge of the tool was all in one plane, it described a curved path normal to the board. To check for a high fret on a radiused fretboard, the edge of the tool must be straight in two planes.

Happy new year to you!