Fingerboard Purfling?

[j. pierce]

Hopefully this is under the right forum, I'm assuming purfling falls generally enough under the category of "inay".

Enamored by garehanman's "tang top" a well as some of the other projects I've seen since joining PG, I'd like to try my hands at purfling along the fingerboard - but one part is alluding me - how to route the channel?

My understanding was to simply use a bearing guided bit to cut a ledge, much like cutting a binding channel, glue the binding to edge of fretboard (prior to attaching to the neck) like i did in my previous builds, simply using one of those teflon filler strips sold for this purpose to fill the space that would be taken by the purfling, pull the strip and install the purfling. (Garehanman elaborated on the details of the final point for me in thread around his "tang top")

Part that's getting me is radiusing the board -

If I route the channel for binding prior to radiusing the board, it ought to be easier, but I have to deal with the fact that the purfling is very thin and a the board widens, the edges get narrower because of the radius. I risk sanding through the binding towards the higher frets as I radius the board, or if I overcompensate for this, I end may end up having an excessive amount of sanding to do to get the board level with the purfling. I'm afraid if I attempt to compensate for this (by routing slightly deeper as I go up the neck) I may foul things up and find myself sanding more to to reach the further recessed purfling at the high end, forcing me to sand through the purfling at the low end in an attempt to keep the board level. (Is there a way to calculate how thick the board will be at the edges after I radius it at certain fret positions, if I know the width of the board and the scale length, radius, etc?

If I route the channel after radiusing, that solves some of the problems with making the channel "blind" as it were, but now I have the added difficulty of routing a curved surface, and I still may have to take into account the varying thickness of the edge of the board as I route the channel (although doing it in steps or setting up some sort of a tapered surface for the board to run on, while the router runs on flat rails alongside it may resolve that issue, I am uncertain.)

Perhaps I am overthinking the problem and isn't really an issue, on one of my first inlay attempts, I did have problems related to the thinning of the board at the edges as I went up the neck. A lot of this had to do with inexperience, however, as well a the fact it was a rather wide inlay on a bass neck with smaller radius and dramatic taper.

But does anyone have any ideas? Any help is appreciated.

Also, I'd prefer to do this on a fretboard prior to installing it on a neck, if at all possible - so if somehow there's a major screw up, I'm only worrying about replacing a fretboard, and not getting the board of the neck. (Although, that's probably something I should learn to do!) Of course, hopefully practicing on scrap will help prevent that possibility.

[thegarehanman]

If you use shell for purfling, route the channel deeper than it needs to be. Then radius the board before installing the purfling. Glue the purfling into the route, being carefull not to get any epoxy in the fret slots. This will allow you to avoid much sanding of the inlays. If the route is still deeper than the thickness of the shell, just use epoxy to under the shell to get it to the correct height. As long as you're working with epoxy that's fairly viscous, you shouldn't have any problems.

peace,

russ

[Mattia]

Routing a curved surface (especially a fingerboard) isn't as difficult as it would seem. I'd probably go for the 'route after radiussing', so you can accurately dial in the depth of the route. I do all the inlay on my fingerboards after radiussing and slotting.