It seems like a simple problem, but I’m finding that it is not. I recently did a refret on a strat for a customer. Upon completion all frets were level to my level. After a month the customer comes in complaining that there are high frets here and there. The guitar plays fine with extra low action, but he has found with a fret rocker that there spots that seem like there are high spots? I was at a loss for word as I have never had such a happen before. I got my fret rocker and checked the spots he was concerned with and he had a point in a couple spots!! Wow… I have him leave the guitar so I can remedy his concerns. I then re evaluate mY SM fretrocker. Bam! It is not perfectly flat! It has machining marks like chattering where it was cut. It might be straight but not perfectly flat so I can see how I could get an inaccurate reading if one/two frets fall into the shallow machining spots.I go ahead and sand it true with my granite block and check the results. There are still 2 spots of concern even after leveling!!! How can that be? How can I have a fretrocker rock with frets that I know are level/straight? Anybody else’s SM fret rocker have these machining marks? Anyone experience this?

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I've had some inconsistent readings (albeit very minor) between few different fret rockers, so my M.O. now is to use a couple of them to "cross-check" and take averages until everything seems to agree. 

Then, of course, there's the issue of frets always moving around a tiny bit, especially being freshly-installed and then after a month's worth of playing on a guitar set up with "extra low action" in the first place.

If you're seeing chatter/machine marks on your fret rocker... send it back.  StewMac's known to be pricey, but the upside to that is the phenomenal customer service.  If you're dissatisfied with their fret rocker, they'll absolutely replace it.

Finally, it's really neat to see someone posted something fresh on Dec 6th, as I was afraid the whole site would have gone a solid month with zero activity!  Nice to see we dodged that bullet, eh?  Happy holidays :)

Thanks for the reply! I was starting to feel like I was on crazy pills. I guess I’ll have to start doing that as well with a couple rockers. I have already ground my SM rocker flat with my granite block. Happy holidays! I’M NOT ON CRAZY PILLS!!! HA HA

I’d second the Stew Mac customer service comment. Always responsive and fair. When starting out, I used sections of drill rod for fret rockers. Accurate but a bit “rolly.” Cheers.

Sure the fret rocker was never intended to be anything more than a quick and dirty check.  We have mixed feelings about the tool and say so in the fretting classes that we put on from time to time.  The biggest problem with the fret rocker is it only gives one a very specific view of a very small area.

We use flattened and checked leveling beams that we flatten on certified surface plates and check annually for flatness.  A typical beam for us covers the 1st through the 12th and then shorter beams for the rest and longer for basses.  It's our approach that you cannot approach quality fret work in isolation and must always have a view of the entire fret plane as the natural straight edges the strings... see it.

So these are the kinds of things that we read that make us tell our students that the fret worker is a triage tool for incoming in a repair shop.  It's not a decent tool to gage your fretwork chops or the bar and the quality of what results will be substandard in our view again because of the limited view of only three frets not the entire fret plane as the strings see it.

So how do we know when we have the level set that we want?  Before I answer this question I will add that when we do a fret dress or refret we have relief added to the treble side, more relief added to the bass side, fall away milled past the 12th and once in a while a special consideration such as changing the neck angle in a fret dress for an instrument on the cusp of a neck reset.  But back to the question we use ink on the fret tops and work to eliminate the ink or "bluing" in machinist speak. We estimate that ink film thickness to be around .0002ish so the tolerances are pretty tight for us.

With our approach and methods to quality fret work we've never had any complaints or returns or anyone finding high frets.  We also been able to satisfy some A-list players who of course wanted action below low.....

I'll add I may have missed it but gluing is advisable too and we glue all our frets and reglue all frets for fret dresses before we begin.  It's pretty common to have loose fret ends that rise and fall with a little pressure and can fool a fret rocker depending on how hard you press down when using it.

By the way we have same view of the neck jig from SM, nice demonstration and teaching tool but not for a commercial shop who understands what happens to a P bass neck with gravity.  We ended up hanging our aprons on our neck jig until we decided to part it out and use the dial indicators elsewhere.  But it was interesting to see the interaction of guitar position and the neck.  It was interesting for about a week then it was in the way... :) 

I do use the fret rocker to confirm a high fret but since I'm not looking for any real precision out of it we don't flatten them beyond a visual check.

Consider using ink when you level and learning to read the remaining ink.  You can do incredible things in shaping a fret plane with a simple precision leveling beam, ink and a good technique.

I use the Stewmac Erlewine Neck Jig every time I do a refret, I would not consider doing it without it. It's a great tool, well worth the money.

The only time I use the fret rocker, besides checking out a guitar with problems or a guitar that is up for recrowning, is right after mounting the frets to spot erroneous frets that didn't seat well before doing the crowning.

Go to the search box and type in ‘fret rocker’. 
Scroll down to “Topic: touch up frets advice”. 
This discussion (IMO) remains the definitive science of the proper way to be assured of evenly leveled frets. 
It’s a long but supremely educational discussion. 
The only other bit of opinion I can contribute is that all frets should be leveled after a fret job regardless of the methodology. 
Remember that we work with tolerances of thousands of an inch.
Our eyes are useless in that realm so we must rely
upon me machinist’s approach for assistance. 
Everyone be well and have an enjoyable holiday season,


Hey Paul it's been a while my friend.  I wanted to answer some of your comments here if I may please.

We start with leveling everything and adding fall-away and then after we have a level set we mill in relief where a specific neck wants it based on how the truss rod impacts the neck when adjusted.  We actually do this to the board too before fretting so very little material is removed from the board.

The method we were teaching when we were having classes pre-covid works to tolerances of a few ten thousandths of an inch using the thickness of bluing/marker ink as our closest tolerances.

For us it goes down the presence or absence of the ink which we think is a couple ten thousandths thick.

Now none of this uber accuracy is necessary for most players but we have clients who are pros and want super low action and we can get it for them with our approach.  

What I am describing was developed over some years of trial and error also trying to use the neck jig for the process but we found it slowed us down, was redundant and we can observe tighter tolerances with bluing/ink.

Happy Holidays to you too Paul

Yes, that was a good read. It's important to know that a fret rocker is a very near-sighted tool, the neck and fretboard as a whole must have the right shape to begin with. The rocker can only be used to evaluate local problems with high frets.

I might add that I for the most part have the luxury of straighten the neck with a carbon rod and sanding the fretboard to a nice even, small relief before final fretting using the fret press method. The Stewmac jig is a must for me since I don't have a truss rod to adjust the relief, without the jig the relief will be a roll of the dice with strings at tension. The jig is surely not the fastest way to do fretwork, but for me the only way.

I am in England, UK:

I had exactly the same problem a few years ago which cost me 2 x refrets I had to redo plus a stack of cash where I had to reimburse another customer half the price of a badly made Warmoth neck! The fret rtocker in question was made by a European company Guitars and Woods (I no longer deal with them after I had the same problem with some of their aluminium radius beams too)! I also had a dodgy StewMac fret rocker that I ordered after the G&W affair. SM reimbursed me and said they woiuld check their stock and I heard nothing else about it. That said, most of my tools are SM and I am more than satisfied with their tools.

Tool brands I use and trust are StewMac, Philadelphia Luthier Tools (both US), Guitar Builder Online (Canada), GMC (Wales UK), Tonetech Pro (England UK). My favoured fret rocker (I have 2) are by GMI (Greece, Europe) made by Haris Bakirtzidis (Halon Guitar Parts: Greece). He no longer makes his GMI tools so you cannot get them but most of my precision stuff was made by him.

Always check your fret rockers with maybe a Veritas (Canada) straight edge...

PS: StewMac customer service is second to none! Even for a StewMAX account holder based in England! Because of their 'if it is no longer working as it did when you bought it, we will replace it for free' stance! I have been able to sell my backup tools (I used to buy 2 of anything). I can now just get a replacement tool once it is no longer working at 100% capacity! That is a fabulous service...

I think Roger phrased it well when he said the fret rocker "is a very nearsighted tool".  It's great for identifying one suspected tall fret, but that should be about the extent of it.

Personally, I use one for every fret job as it progresses, since identifying a just-installed fret that's not perfectly seated is a lot easier to deal with at the moment, rather than later.... (particularly for those of us who glue:)  

Of course, I'll need to check any given fret after the next fret goes-in, since there needs to be a reference for the rocker to "rock"!  And even then, it's a gamble to bet that fret is seated right!  But at least it forces me to pay attention to good solid seating as I move up the neck.

Hi, before the days of the Stumac Fret Rocker, I was using these, cut from stainless steel rulers. I trued up the edges and check them every few years. Works well enough for me, while I still get good buzz-free low-action necks they will last me a bit longer.

Not as convenient but do the same job...

Cheers Taff


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