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Thoughts on fitting the dovetail - kit

Posted: Thu Aug 22, 2019 2:02 pm
by jread
I post a lot but thought a post on my 1st time dovetail fitting experience would be worth it.

Well, this was by far the hardest part of putting together my Blues Creek Guitars kit so far. John's video's are the only source I found anywhere that gives a new person a good sense of what needs to happen to change the angles and get a good fit. So reminder to anyone needing to fit a dovetail: Google: youtube blues creek dovetail. And thank you John Hall for posting those! They are getting old but still quite useful!

Couple of thoughts:

I should have done a better fit without the fretboard glued on. I thought close was good but I got it set to within a couple of millimeters then glued on the fretboard but now have trouble getting the fretboard totally flush and seated leaving a little gap a the intersection. The angle of of the top doesn't seem to quite match the plane of the neck. John seems to cover this in his addendum video with all the sanding the neck to be flush with the top. I blew that part but it's close and straight. Think I can do better next time but I think I'd have have to remove my fretboard from the neck to do better on this one. It does seat a little better under clamping pressure but the picture shows the challenge.

Ensure the wings stay parallel to the body when sanding for elevation change. Any slight angle will cause a gap and mine was all over the place.

I actually bottomed out ( dovetail hit back wall of slot ) which means I probably sanded way too much from the wings trying to make them flush. Making the slot a little deeper was easy and fixed that problem.

I found that my favorite shim material is spruce scraps from the top with grain running lengthwise. The soft wood is super easy to shape. In gaining experience I sanded my shims to nothing and put new ones on at least 3 times. The original joint as shipped didn't need shims so perhaps with skill, one could just sand, fit, and go.

My dry fit is very tight and my straight edge off the frets is near flush with the top of the bridge so stopping here and calling it good. There are a few gaps in the joint that probably wouldn't fly for veteran builders but i am super happy and am going to wait until my shellac hardens up at least a couple of weeks before trying to glue this on. That is unless you all see something drastic here. :D

Re: Thoughts on fitting the dovetail - kit

Posted: Thu Aug 22, 2019 10:10 pm
by Diane Kauffmds
I just want you to know that your joint looks really good and there's no problem leaving it. It probably looks better than my first neck, and I too, bottomed mine out.

If you decide to close the gap, here's how:

Your neck is probably being held off by material under the cheeks. Chisel a little valley under the cheeks, where you can't see. Just stay away from the edge. I'm sure this will help you sit it down on the shoulders. Also, scribe sanding, which John Hall demonstrates in his videos about fitting the dovetail (on YouTube), will help. Do this after chiseling your valley, if needed.

Otherwise, leaving it is perfectly fine! Good job!

I know this isn't the best drawing and I over emphasized the valley. The valley isn't deep; it's just an area that's above the outside edge of the cheeks of your neck. Hopefully it illustrates what I mean.

I helped another member of our forum with his neck, and I took photos of what I did.
PicsArt_08-23-12.07.40.jpg
PicsArt_01-10-07.06.06.jpg
When scribe sanding, the sandy side of the paper is rubbing the underside of the neck cheeks/heel. Pull downward as you pull through.
PicsArt_01-10-07.03.24.jpg
Notice the "valley".
PicsArt_01-10-07.02.30.jpg
This is the result:
PicsArt_01-09-02.22.03.jpg

Re: Thoughts on fitting the dovetail - kit

Posted: Fri Aug 23, 2019 12:29 am
by jread
Thank you. I really appreciate the feedback. Going to work on closing that gap a bit more.

Yours is gorgeous! I am impressed with the clean edges. I tend to overwork things leaving hand made look.

Actually tried to relieve that area and will revisit.
I wish i left off the fretboard to make the top sit perfectly flush but dont want to remove it now. Will sand under extension maybe.

Thanks again. I second guess myself so posting here has been a great help. Its close

Re: Thoughts on fitting the dovetail - kit

Posted: Fri Aug 23, 2019 2:43 am
by Diane Kauffmds
You're very welcome.

BTW, I always install my necks with the fretboard attached, just like you're doing. It helps to get the geometry right. It just happened that another member of the forum was having a really hard time with it, so I did the work without the fretboard being attached, to get photos.

Just remember to make frequent checks of your geometry while scribe sanding, to ensure everything stays straight.

Don't hesitate to ask anything. Throw me a pm if want. Relax. You're doing fine.

Re: Thoughts on fitting the dovetail - kit

Posted: Fri Aug 23, 2019 2:45 pm
by rcnewcomb
I am watching this thread carefully since I'll be attempting my first dovetail on kit #4.

Re: Thoughts on fitting the dovetail - kit

Posted: Fri Aug 23, 2019 6:21 pm
by tippie53

Re: Thoughts on fitting the dovetail - kit

Posted: Mon Aug 26, 2019 12:35 pm
by jread
rcnewcomb wrote:I am watching this thread carefully since I'll be attempting my first dovetail on kit #4.
Yeah, John's video says it all plus Diane's drawing helped a lot. I've reworked this joint and it looks better if not gapless. This is clearly one of things that seems easy once you know how. That joint is like a Chinese puzzle. I got it tight but my brain doesn't let me know why sanding "over there" makes it tight "over here" but hey, I got it workin mostly.

I'll post again when I have it glued. This project was about increasing my woodworking skills and this step surely did that!

Re: Thoughts on fitting the dovetail - kit

Posted: Mon Aug 26, 2019 9:50 pm
by MaineGeezer
Though some builders are appalled by the idea, the luthier who taught me (who went to luthier school and then apprenticed under Dana Bourgeois) puts a wedge shim between the fingerboard extension and the top. The way he builds his guitars and radiuses the top, there is supposed to be a wedge-shaped gap between the extension and the top.
Others construct the top and arrange the geometry so there is no gap between the fingerboard extension and the top, or at least there isn't supposed to be.

Either approach works. I'd say, if you end up with a gap, even if you were not supposed to, don't worry too much. Make a wedge shim to fill it and carry on. As long as the action height ends up where you want it, I'd say it's fine.

Re: Thoughts on fitting the dovetail - kit

Posted: Tue Aug 27, 2019 6:38 am
by tippie53
I use a wedge taper when I reset for the fall off. Good point

Re: Thoughts on fitting the dovetail - kit

Posted: Tue Aug 27, 2019 3:02 pm
by jread
Cool. I considered adding a wedge there. I saw some wedges under the extension on some guitars but assumed it was to be avoided so thank you for posting! I ended up sanding my top again and the plane matches a bit better. I'm really happy with the fit for my 1st go and it's tight in dry-fit. My angles are good but that little spot is seemingly what will separate my 1st build from more experienced work. I'm not in a rush to glue so will see if I can get a wedge in there or if I'll just keep cranking harder on those clamps. :D