4/16/2015

Workshop: Mandolin Refret


Update: I've now included "part 2" to this in this original post, instead.

I've had a number of folks ask for some sort-of tutorials on work stuff. Here I'm refretting a nice old Gibson A-4 from the teens which has had the "usual" neck warping over time which will require a fret pull, board level, and refret. I see this a lot on old Gibson mandos after they've been subjected to mandolin 11s (ick), regardless of truss rod or not.

First I had to carefully take off the celluloid binding... which I did with a really sharp angled chisel... very carefully!




Next is to mask off the work area... and the finish is in good shape so I'm not worried about peeling it off. On fragile-finished instruments I generally use scrap fabric instead. Note how I've already popped the nut off with a light whack of a hammer and wood block.


Now let's pull the frets!

These are tiny, tiny old Gibson stock so my end-nippers/fret pullers won't be able to grab them as they're so low. Here I'm using a flat chisel to "tuck in" under the edge and rock the treble side of the fret free enough...


...to grab with my nippers. Next I simply run the nippers along, rocking them lightly, to pull the fret loose. You have to be very careful not to chip the board when doing this bit. I always watch to see if I'm pulling up the board in fragments... especially in dry old ebony like this or even more-so in those dyed maple boards typical of the 20s/30s.


Here's the fret removed. Note the slight chipping. It won't matter as that'll be leveled-down anyway, but also hidden under the new fretwire.


Here I've removed all the frets and have begun leveling the board with 80-grit sticky sandpaper attached to my StewMac leveling beam (heavy steel unit). The weight of the leveler helps sand it down level quickly. I'm removing almost 1/32" overall warp on this board.



This board is so absurdly fragile (it was chipping) that I can't use my normal fret-slot cutter (with depth stop) and instead have to use my mini-hacksaw with a narrow blade.


Here's my normal StewMac fret-slot cutter.
  


So, with the board leveled, polishing begins by upping the grit # on sandpaper and then polishing-up with 3M flexible polishing paper.


Here I'm getting the needed cut length...


...and snipping it with my well-chipped nippers.


I then file it to as close a fit (and remove "barbed" edges) with the sides of the board as I can... here's a flat-file clamped up to make this job easy.


Normally I don't glue frets at all, but I'm using a few dots of "medium viscosity" super glue in the slots to hold these as the ebony is rather fragile and I don't trust it to hold the frets nicely over time.


I then use a C-shaped neck "caul" against the neck rear and flat-profile wooden block on top and a clamp to press the fret right into the neck. This is a good way to do it for a sure, tight fit and StewMac actually sells a very cool (and expensive) "Jaws" unit that does all this quickly with a spring-loaded grip (it's on my "someday" list of tools). Because I work on so many oddball instruments with differing specs... I find this way works alright, especially since I can profile my clamping block however I like to match a different radius.


A more traditional way is with a dead-shot/fretting hammer... like this one... which is very useful for tucking loose frets back into fretboards but not something I generally do when refretting from scratch.


The next bit is to remove the remaining fret overhang from the board. I've actually done it, in this pic, already but this gives you an idea...


Then I make sure that the frets are all 100% level by very lightly leveling-off with 200-grit sandpaper.


I finish dressing the fret ends and polishing up the frets... and then it's time to tape the binding back on. I usually bevel the ends of my frets less than most people and "round off" the ends of them more instead... this gives a bit more "fret" to bend your strings against at the edge of the board.


This customer also wanted a new adjustable bridge... so here it is after fitting.

1 comment:

Rene said...

Thanks jake for sharing, very interesting and helpful