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For all the talk of accuracy and repeatability and whatnot, and for all the millions of dollars spent researching and building the Plek process, there's STILL ten guitars down at GC that have been Plekked, that STILL need fret dresses.
I've also re-dressed MANY Plekked guitars and cleaned up notes that were buzzing due to high frets for customers.
What counts is what the customers actually get, NOT what a spec sheet or lab test shows, nor what people put on the internet.
To my mind, the variable that the Plek process doesn't seem to be able to take into account (based on Plekked guitars that I've seen) is the minor imperfections in neck straightness that all Gibsons seem to have, which shows up as an S-curve in the neck. What does the spec sheet say about that?
And even though the Plek guys might be able to come up with some explanatory theory about why their machine works around this variable, how come I'm able to re-dress and improve so many Plekked guitars?
I'm basing my thoughts on a specific company, since I know no one else who has Plekked guitars.
The only Plekked guitars I've ever seen have been Gibson factory Plek jobs.

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Old growth, shmold growth!

I firmly believe it's not the Plek's fault in your case but rather the operator or some other circumstance. The Plek WILL account for the "s curve" in the neck. If it can be dressed out it will do it. If it cannot it will tell you it is beyond range. The Plek is a tool. It still has to be used correctly, and maintained correctly to be as good as it can be. If it is not then the results will be sub-par. If you're a repairman you should know by now not to think anything that comes out of Gibson's shop to be consistent!

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John Mayes
http://www.mayesluthier.com

Isn't that the truth!

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Brad
Avon, OH

To me if you take a plekked guitar in a factory (done correctly) then send it to another part of the country, hang it on the wall of a Guitar Center, let a bunch people pick it up and play it, let the strings get old, and then evaluate the guitar 4 or 5 months later I would surprised if it was playing as well as the day it came off the plek. I had a customer that had 2 guitar plekked...the first was great the second he wanted to me to reset up. I am not convinced the Plek process didn't work but he had to send the guitar away to get it Plekked so by the time it got shipped back it could have been affected by temperature or humidity and the perfect setup was less than perfect.

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Brad
Avon, OH

Yup I know better than to expect anything from Gibson to be consistent.
I also thought that was the purpose of the Plek machine, to improve their consistency, WHICH IT HAS DONE on their Plekked instruments.
I'm also not talking about improving a less than perfect setup from a guitar that has been hanging on the wall for months on end with cruddy strings.
I used to be a third party independant guitar tech in a Guitar Center.
I'm talking about fresh out of the box Gibsons straight from the factory that needed some fret work to correct buzzing frets before going out on the wall, without adjusting the action.
I've adjusted 3 or 4 frets on 1 guitar, freshly plekked, and corrected buzzing due to high frets and not the setup, straight out of the box.

To be clear, the frets were measureably high, and causing noting out before I touched them, the frets were measureably level and NOT noting out AFTER I touched them, and these were brand new guitars straight out of the box from Gibson, with the "Plekked!" stickers on them.

I'm sure my experience is not unique.

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Old growth, shmold growth!

I'll quote myself here....

". It still has to be used correctly, and maintained correctly to be as good as it can be. If it is not then the results will be sub-par."

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John Mayes
http://www.mayesluthier.com

Thinking about the Plek process makes we wonder if anyone has designed and built a simplified manually operated version?
I have wild visions of an XY positioning system that would straddle the neck with an indicator(s) mounted in what might be a Z axis.
Would be great if the machine had the capability of "scanning" each string path checking each fret in the process and perhaps doing this in both the strung and unstrung mode. Would be sorta like Dan Erlewine's neck jig in some respects.
Nelson

That sounds more like loose frets to me. Did you hit them with any thin CA before leveling?

I don't recall the fret being loose. It worked when I was done with it.

If frets are loose, they simply don't level out.

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Old growth, shmold growth!

I had a similar thought but haven't come up with anything yet.

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Brad
Avon, OH

Someone has surely set a finished neck or complete instrument up on their CNC and did a simple probe with an indicator in the spindle. Guess a guy could program a motion along a string path going in G00 between frets and then slowing down to a very slow feed rate going over the fret(s) so a reading could be observed and/or recorded. Someone with programming skills could probably set up with a digitizing probe in the spindle and record the high reading of each fret and save into a file. Then, of course, he would probably want to graph each string in Excel. The possibilities are endless but it would take someone with a lot more smarts than I.
Well shoot, we just as well then replace the probe with a high-speed grinding head to dress the frets. Not trying to be a smart a** here, just thinking outside the box a little. (I've got to quit that)
Nelson

There are worse individual problems in CNC* but this one'd still be a big time-suck to implement right. The measuring and grinding parts aren't too bad, but I think their system corrects for the shape of the neck under string tension VS without, compensates for the misalignment between the two measurements, and figures out how to achieve the correct grind while removing minimal material? Those last ones are pretty gnarly programming problems, and it'd take quite a few PLEKkings to pay it off

A dumber system could probably do good work with an accurate and repeatable CNC and a user who could fit all those things by hand in Rhino or something similar. Still, though, that sort of work would be tough to pull off in under two hours (to make it profitable), though that is a more reasonable 5-100 hours at luthiers' hourly rates <G>

*: Deriving closed form inverse kinematics for robots with six or more axes is designed to make you cry.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

A number of years ago I built a 30" acoustic baritone for a client that was tuned EBGDAE (that's right, low to high, backwards), gauged .010 to .100, with the high E being the same as on a guitar and the low, the low E on a bass. I had pretty good action on the guitar, around 4 and 2 at the 12th. Not bad given the .100" on the bass. Nonetheless, the client had modest hands and had been used to the feel on his 30" Jerry Jones tuned the same way with different gauges, and wanted it lower. By this time he'd moved to Nashville so I sent him to Joe to have it Plek-ed.

Joe wasn't able to lower the action much. As a follow-up, I emailed Joe, thanking him for the work and asking him for an evaluation of my fret work. I was happy to learn that there wasn't anything wrong with my fret work, per se, as I was within the top 5% of everything he sees. I was not perfect, and he was able with the software to identify some areas that weren't faired cleanly, being a little flat.

I think its a marvelous tool that like any operation, when properly implemented attain results not possible with the same level of consistency and speed. For the client that needs the absolutely lowest action possible, and for problem instruments, its a great tool.

One complaint I've heard from a local repairman was that the frets still had to be sanded and polished after he got a client's instrument done on the machine in our area.