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Neck extension backbow help
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=3697		 Page 1 of 1
Author:  Laurent Brondel [ Tue Nov 01, 2005 11:53 pm ]
Post subject: 
(Long post…)
Just did a refret with large fretwire, this one has a longer tang than others
I've been using, no problem I cut the slots a bit deeper on the
fingerboard. It seems also that the tang width maybe a few mils too wide,
I use a Japanese dovetail saw for the fret slots. The frets seemed to go a
tad harder than usual, but not so hard that I had to pull some frets out
because they didn't go all the way. Anyhow, I'm left with a slight backbow
on the neck, which is fine, it all comes back with string tension, but there
is a good backbow on the neck extension on the upper part of the guitar
body which makes the top slightly sink toward the soudhole. I pulled the
frets from the 13th fret up, hoping to enlage the slots and super-glue the
frets there, but the backbow on the neck extension is not going
anywhere, it seems to stay. There's maybe 3/64 depression at the very
end on the fingerboard, the neck extension bows down from the neck/
body joint. Any advice to get rid of the backbow there? Should I remove
the frets on the remaining part of the neck?
Author:  LanceK [ Wed Nov 02, 2005 12:05 am ]
Post subject: 
A few thoughts - im sure others will have more -
Was the back bow in the fretboard extention there before you did the refret? had you just not noticed it?
Secondly - Is the truss rod set to nuteral?
Finaly – Its not uncommon for a fretboard to drop off after the neck to body joint.


Just some random thoughts -

LanceK
Author:  Pwoolson [ Wed Nov 02, 2005 12:31 am ]
Post subject: 
This is the problem that has caused me to entirely redesign my neck joints.
As Lance said, it's common and often good for the fretboard to drop away a bit at the body joint. But my problem was that the back bow was in the fb prior to installing on the body. When I forced the tennon down into the mortise, there was a hump created at the 14th fret which made the guitar unplayable above the 7th fret without buzzing.
The fix for me on this batch is to remove all the frets, flatten the board (which shouldn't take much) glue down the extension and refret. I usually don't glue down the extension until I'm done as I have a lot of neck on-and-offs during setup. Now the guitar is setup so there will be no on-and-offs needed.
Author:  Michael Dale Payne [ Wed Nov 02, 2005 12:50 am ]
Post subject: 
I am with Paul here remove the frets level the FB and refret. I had one resently that got the hump Paul discribed. This is one reason I always level the fb after I install the neck.
Author:  Bobc [ Wed Nov 02, 2005 2:56 am ]
Post subject: 
I still don't understand why we have to hammer frets in place thus intentionally introducing a back bow? I like Sylvans old method of a hand press fit and glue. It really eliminates all that induced stress.
Author:  Laurent Brondel [ Wed Nov 02, 2005 7:28 am ]
Post subject: 
[QUOTE=LanceK] Was the back bow in the fretboard extention there
before you did the refret? had you just not noticed it?
Secondly - Is the truss rod set to nuteral?
Finaly – Its not uncommon for a fretboard to drop off after the neck to
body joint. LanceK [/QUOTE]

[QUOTE=Pwoolson] As Lance said, it's common and often good for the
fretboard to drop away a bit at the body joint.[/QUOTE]

There was no backbow before fret installation and the rod is on neutral. I
planned the fingerboard before hammering the frets in and yes, I always
sand a little "ramp" at the end of the fingerboard to avoid buzzes there
when the body compresses with string tension. There was no hump at the
neck/body joint either as I flattened the fingerboard before installing the
frets. I guess I'll remove the rest of the frets and re-flatten the board…
Bummer!
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