| Q: Hi my name is Jason and I've been trying to teach myself how to
build a classical guitar by reading books and reading info off of the internet. When
gluing the fingerboard to the neck I have a problem of having gaps you can see from the
side. When I use wood filler it never seems to look right. Is there anything
I can do to
make this look smoother. The fingerboards I use are preslotted and usually rosewood. If
you have any advice I would greatly appreciate it. (February 1999) A:
Three things will have a bearing on the glue joint gaps problem, Jason:
(1) The fit of the fingerboard to the gluing surface of the neck must be
true. It's important that the neck gluing surface be very flat from side to side of the
neck and that it be straight from end to end. Same thing is true of the fingerboard gluing
surface. This is so that the gluing surfaces will be as close to wood-to-wood as possible.
(2) You need to use lots and lots of clamps when gluing the fingerboard. I use over 30
clamps...there're just about as many clamps as it's possible to squeeze into the available
space. It's especially important that the fingerboard edges be clamped, as there is a
tendency for the neck and, especially, the fingerboard to go convex because of wood
expansion from the water in the glue. (Do not use epoxy to glue a fingerboard as a way of
defeating this; epoxy creates a moisture barrier between fingerboard and neck which will
cause neck backbow when humidity rises.) I use strip cauls for clamping in order not to
damage the fingerboard surface. Do not dampen the gluing surfaces before applying glue;
this will help minimize expansion of the gluing surface.
(3) Use lots and lots of glue when gluing a fingerboard to a neck; you will want to see
great globs of squeezed out glue...cleaning that up is the least of your problems. This
helps make sure there is something between the fingerboard and neck and not just air.
|
| Q: I have a few questions concerning your method of fretting. What type of epoxy
do you use? What wattage infrared lamp do you use? Have you ever had the fingerboard
loosen up on you from the heat? Have the frets ever lost their bond? How do
you keep the epoxy from sticking to the fingerboard? (Dave Schramm --March 6,
1998) PHJ: The epoxy I use is purchased at:
Fantastik Plastiks
3132 Gilham Plaza
Kansas City, MO 64109
(816) 561-0402
It is a 4-1/epoxy-catalyst mixture and cures in ca 1hr under infrared. I have used this material for years because it's exactly the
right viscosity for fretwork, viscous enough so it won't run out of the slots, thin enough
so it can be injected into the slots with a hypodermic needle small enough to go into the
slot. Also it does not produce bubbles under curing
heat like other epoxies. I repackage the components in 60ml hypodermic
syringes, no needles, for dispensing small amounts. Fantastik Plastiks specifies a shelf life of 6 mos., but I have successfully
cured material well over a year old under infrared. Nevertheless, I try to turn over
my supply at least once a year. I usually to
Fantastik Plastiks to purchase the material; shipping via UPS/Fedex
requires hazardous material handling and therefore an extra charge.
The infrared lamp I use is 250W. This is a standard wattage, and these
lamps are available at hardware stores, Home Depot, etc.
I've wondered if fingerboard separation is a possibility, but it's never happened to me.
I'm sure the glue holding the fingerboard to the neck softens a little, but it
appears as long as the joint isn't under stress this isn't a problem...the glue just
hardens back up when the heat is removed.
I've never had frets installed with epoxy come loose by themselves, only when I've
applied heat with a soldering iron to remove them. One of the best features of this
fretting method is that the frets remain perfectly stable indefinitely.
To keep the epoxy bead which is squeezed out when the fret is installed from sticking to
the fingerboard, I use a material called PartAll, a release agent for fiberglass
reinforced plastic molds which comes in a paste form.
It is applied with a cloth pad,
wiping off the excess. The epoxy beads usually pop off pretty easily with a chisel
knife, often in one long piece. PartAll is available anywhere fiberglass reinforced
plastics materials are sold (Fantastik Plastiks has it).
I cut the fret slots overlarge so they're big enough
allow the frets to be installed without pressure or hammering and have
enough room to inject the epoxy into the slot with a 3ml/21g hypodermic
syringe (used by diabetics). This enlarging can be done with a
dovetail saw, but a better way is to use a dental bit in a Dremel tool with
a router base; this method also permits reslotting a bound fingerboard
without removing the binding. For guitars, I use a Henry Schein FG-556
carbide bur; a smaller bur may be needed for smaller frets (mandolin,
banjo). You should be able to get these burs from your dentist.
Once the frets (pre-bent so they have a little more arch than the
fingerboard) are set in place in the epoxy-filled slots, I use two metal
rods clamped lengthwise to the fingerboard under a caul to press the frets
to the fingerboard during the cure. Protect the instrument from curing
heat with pieces of tinfoil shiny side up. |
