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Dovetail shims

Posted: Tue Jun 28, 2011 11:35 pm
by MKlee
Before installing my fretboard to the neck I felt I had a very good dovetail setup between the neck and the body. I followed John's video to the "T" and all was great.

However, once I glued the fretboard to the neck AND added the finish to the guitar body and neck, I'm now having a terrible time with the joint. The biggest issue seems to be caused by the curvature of the fretboard (caused by installing the frets) on the part that extends beyond the neck and onto the body of the guitar. This curvature tends to push the fretboard away from the body at the dovetail.

I guess this is all trivial information to asking my question .... I now need to add some shims to the joint to tighten things up (I think). What is the best way of making shims and what material is best to use? I inserted a 1" piece of index card on either side of my dovetail and it seems to make a considerable difference in tightening the joint - I'm just not sure the best procedure for making the shims.

Also, any recommendations for not making this mistake on my next guitar would be greatly appreciated.

Mark

Re: Dovetail shims

Posted: Wed Jun 29, 2011 6:47 am
by tippie53
What Rick said is sound. Sometimes that little distortion is enough to kick the dovetail joint apart. I always use a clamp to get the best bite I can , and yes, sometimes a small shim is needed.
On your next fret job , don't be afraid to clamp the fretboard with some reverse bow. The bow is often caused by the barbs . They have to seat into the wood. Like Rick points out , there is a good bit or pressure asserted from that plus add the shear , there is some heavy loading going on.
Keep us posted

Re: Dovetail shims

Posted: Wed Jun 29, 2011 9:10 am
by Tony_in_NYC
I dont use a dovetail joint, I use a mortise and tenon, but the back bow of the fretboard extension is still a problem when bolting on the neck. I need to use a clamp and two cauls, one on the back of the body and one on the fretboard itself right above the neck heel, to get the darn thing fully seated. Then I have to tighten the bolts that hold on the neck. You will only have to use the clamp(s) to push the dovetail joint home and leave it until the glue dries.

Re: Dovetail shims

Posted: Wed Jun 29, 2011 11:41 am
by tippie53
I will be doing some videos this weekend and I may address this on one . Since I started to back bow the fretboard , it seems to have helped get the extension to seat the barbs and straighten out .

Re: Dovetail shims

Posted: Wed Jun 29, 2011 10:18 pm
by pete nardo
I believe these issues are the reason the stew-mac kit instructions recommend installing the frets on the fretboard extension after the neck is set.

Re: Dovetail shims

Posted: Thu Jun 30, 2011 9:12 am
by MKlee
Thanks folks, for all the input. As it turned out, the fretboard was about 1/4" too long too - so when I cut off the extra length it helped a lot with the extension curvature since most was at the end of the extension.

I'm going to buy shims today and rework the joint to get it back to where it was before the fretboard. I appreciate the input.

Pete, sounds interesting about waiting to install the frets until after it's all glued up ... but how do you seat the frets while they're on the body? Seems a little scary to me to be pounding on the finished guitar?

Re: Dovetail shims

Posted: Thu Jun 30, 2011 11:11 am
by Ben-Had
MKlee wrote:Thanks folks, for all the input. As it turned out, the fretboard was about 1/4" too long too - so when I cut off the extra length it helped a lot with the extension curvature since most was at the end of the extension.

I'm going to buy shims today and rework the joint to get it back to where it was before the fretboard. I appreciate the input.

Pete, sounds interesting about waiting to install the frets until after it's all glued up ... but how do you seat the frets while they're on the body? Seems a little scary to me to be pounding on the finished guitar?
You need some special tools. A fret dolly (hammering) and Jaw 2 or 3 (pressing) are a couple. Probably are others. I hammer the ends down then press them in.