The following image is of a tread depth measuring digital micrometer which is the absolute bomb for measuring fret heights along the board, with the strings on if necessary, to within a thou or so. We originally got it to measure frets after insertion for QA, but quickly realised it demonstrated to our Service customers what their frets looked like and what were prudent limits for wear and whether a refret was necessary. We can talk about this all we like to customers but a visual show and tell along the board is far more illustrative and reassuring to customers who are contemplating a refret/level. They also make a great depth gauge and tool setter, which is a bonus.
Anyway, the good news is these things sell on Ebay (add Ebay China to your google search line) generally with free ship from China/HK for around 10 bucks.
Calipers (both digital and dial) have a similar finger at the back end. probably not quite as accurate as the dedicated tool but most of us have 'em in our toolboxes already. For those in the U.S., check Harbor Freight stores, too. they have all kinds of inexpensive measuring tools.
Yep, that's what we used to use but as the end of the measuring post on traditional doesn't bridge or sit dead flat between frets we demonstrated that just a small amount of lean from true vertical in either axis with the calipers put the measurement "off" by a couple of thou, which is less of a problem with this tool.
But, to reiterate from a "clinching the deal" with the customer point of view: Surprisingly, the customers understand it's representation and like its "user friendly" way when discussing fret work and that was more of the reason for putting this one out there for our members.
It's largely dependent on the type of guitar and the type of playing that it is subjected to. A light touch jazz player can play fretless (and some do) whereas a two and a half step bender with finger vibrato on all four will usually require a jumbo height (but not necessarily width) fret to get under the strings at the demonic end of the register.
My magic number at the cowboy chord end of the neck is nothing less than 25 thou for the average hacker whereas for the heavy rock gods we reckon that 30 thou is the end of it. Bear in mind that a thick lacquered vintage Fender Tele neck can be 35 thou brand spanking new out of the box, and it can get a little awkward explaining why these skinny frets are going to go away very fast.
Strings make a difference for sure with pure nickel, steel wound, cobalt wound, stainless steel wound all making some difference particularly if heavy vibrato and bending is in play, but knuckle-draggers with the grip pressure of a pit bull bite will make frets go away faster than any other factor and they should be offered stainless as an option.
I'm interested what all the other guys here use for their minimums and how they go about compensating for various factors in modifying these figure , it strikes me as very valuable knowledge to have to inform customers of the group average figures for dictating what sort of fret work is required on the day.
I've always used about .030" as my "last gasp" number or, rather, to explain the difference between a customer needing a fret dress or a refret.
To be clear, I'll dress a .030" fret but then tell the customer that, next time, we need to look at some spankin' new frets. Used-to be gung-ho on recommending stainless but have gotten away from that unless someone is particularly heavy-handed and the frets are wearing fast.
Never really thought much about the rockers vs. the strummers but it makes sense, Rusty, and I'll surely inquire as to playing style next time 'round.
stu mack sells a straight edge that sets over the frets ad checks the streightness of the finger board.I don't know why. you cant do anything with the board with out the frets out! All new guitars I get in the shop need the frets leveled! Martin and all! I use blue felt markers on the crown of the fret - adjust the truss rod level as I can with 15 lb weight on the guitar so the guitar thinks it has tuned strings on it than I have a alum straight board 3 inches wide and sandpaper glued on it and start leveling the frets. You will find the frets are all over the the place for height.
You need to replace the frets when you cant recrown them any more!
This what Martin guitars do as I found this in their paper work. They say we don't send out a guitar until it has hang in their factory for 2 weeks and Tayler says we build them right so we can send them out right away.. Test the board on their guitars and it needs set up!
Rusty - I have a regular digital caliper (overpriced Stewmac... but it works) - anyway I use the end of it the same way you're using the tread depth tool. By calibrating it to "0" when the end of the "slider" is flush with the end of the body - I can get fairly accurate fret thickness measurements over the frets. It's not perfect because the tool was not designed to be calibrated that way and you're working a square end against the fretboard radius - but it works OK for determining if the frets need replacement. Another way to use it - when the tool is zeroed out on the business end - the "slider" is about 1/8" shorter than the tool body, and it's built with a notch at that end, so you can set it over the fret and then extend the slide until it touches the top of the fret- what you're measuring is the difference so the higher the measurement, the less fret you have left. Again - it's not perfect but you can get a relative measurement for "go" or "no go" on the fret job. I'm not trying to discourage anyone from buying the tread gauge -it's obviously a better tool for the job - but that said I know a lot of folks have under-utilized digital calipers sitting around. It's another option - that's all. Best Rgds.
Oops sorry Larry Klose - my bad... now I see basically posted the same thing you did. Should have read first - no offense intended.