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 Post subject: Fretboard bowing
PostPosted: Tue Aug 28, 2018 11:35 am 
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Joined: Wed Jan 04, 2017 1:30 pm
Posts: 15
Good morning. I have an issue with the fretboard on my current build bowing after the 14th fret. All seemed to be going well until I installed the frets. The fretboard was flat and now when I go to attach the neck you can see there is a gap where the neck meets the body. These are medium frets which I haven't used before and installing them appears to have put a bow in the fretboard. I think the neck angle is correct and other than the bow I should be OK with the geometry once the neck is set.

Question is what to do now? I can probably set the neck and force the fretboard flat against the top but I think that will put a lot of pressure on the top. Or I can shave the underneath of the fretboard down at an angle so it sits flat against the top, but then I will have a big dropoff in the lower frets. Or should I remove the frets and do something different? I don't want to ruin what has been a pretty solid build so far. I did do the fretwork and the neck angle set work in the garage shop where the temp and humidity are high.

Dave


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 Post subject: Re: Fretboard bowing
PostPosted: Tue Aug 28, 2018 5:03 pm 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 5884
Location: Hegins, Pa
this is typical
the fret tang and barbs cause this . When you clamp it in it will flatten out

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 Post subject: Re: Fretboard bowing
PostPosted: Tue Aug 28, 2018 10:34 pm 
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Joined: Thu May 24, 2012 8:03 am
Posts: 1096
Location: Chestertown Maryland
I think what John is alluding to is that your neck is not all the way down in its joint. The fretboard at the body/neck joint should sit on the body. Once the neck is seated you will be able to tell what you have to do next. Check the fretbpoard to see that it is almost straight on the extension - it should not hump up (ski-slope), and if it falls off, it should only be 10-20 thou. Good luck

Ed


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 Post subject: Re: Fretboard bowing
PostPosted: Wed Aug 29, 2018 6:25 am 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1162
Yeah. The fret tangs apply pressure in the slots. The pressure can cause the fretboard to curve down. If the amount of curve is "small," you can mash it flat when you seat the neck.

The curve can he significant enough, however, to make the fretboard strenuously resist being flattened. If that's the case, there are two ways to fix it. You can either make the slots wider, or get frets with thinner tangs. John sells fretwire with various tang thicknesses, from 0.0185" to 0.0245". http://www.bluescreekguitars.com/shop/i ... oducts_all
Get a few and test for fit. If you want, you can fit frets 14+ quite loosely and secure them in place with a bit of CA glue.

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 Post subject: Re: Fretboard bowing
PostPosted: Wed Aug 29, 2018 3:43 pm 
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Joined: Wed Jan 04, 2017 1:30 pm
Posts: 15
Thank you all for the advice. I think the pressure required to flatten the fretboard against the top to get it to sit flat is enough to be a concern. It will flatten out, I put the neck on with a clamp and it did flatten. If I choose to go with removing the frets, how does one go about making the slots wider without ruining them? Sorry, I haven't had to do this before.


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 Post subject: Re: Fretboard bowing
PostPosted: Wed Aug 29, 2018 4:13 pm 
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Joined: Mon Jul 28, 2014 7:50 am
Posts: 666
Location: Chadds Ford, PA
TXFlatSix wrote:
Thank you all for the advice. I think the pressure required to flatten the fretboard against the top to get it to sit flat is enough to be a concern. It will flatten out, I put the neck on with a clamp and it did flatten. If I choose to go with removing the frets, how does one go about making the slots wider without ruining them? Sorry, I haven't had to do this before.


One thing you might do is watch some of the neck setting videos by John (Blues Creek) where you'll see he cranks down pretty good on those joints. Based on your pictures, that's just about where I would be, and all of my finger boards have that slight down curve from fretting. BTW that gives good contact to the top on the extension area. I think John mentioned that your joint might be a little proud of the perfect seating. I'm no expert, but I did take training from John and for the dozen I've built many look like yours and all have fit just fine with good clamping pressure.


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 Post subject: Re: Fretboard bowing
PostPosted: Wed Aug 29, 2018 4:55 pm 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1162
You could try running a strip of sandpaper through the slots. I'm not sure how satisfactory that would be though. What you really need is a saw slightly wider than than current width of the slots, but that may be difficult to find.

I think the easiest and most satisfactory thing to do would be to get some fret wire with a slightly thinner tang. John sells fret wire for $8.75/lb, so it isn't a huge amount of money to get a few sizes and try them.

I had the exact same problem on my 3rd guitar as you are having, and the thinner tang fret wire fixed it. I think I used a 0.0195 tang. The size you'll need will depend on the width of the slots you have and the hardness of the fretboard wood; the barbs on the tangs will sink into softer wood more readily than into harder wood.

That's another thing you could try; mash or file down the barbs on the fretwire you have, and see if that helps any. Without the barbs though, you'll probably need superglue to keep the frets secure, and removing the barbs may not be sufficient.

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Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion


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 Post subject: Re: Fretboard bowing
PostPosted: Wed Aug 29, 2018 5:07 pm 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1162
Re: what Danl8 said. I agree -- the amount of curvature you have doesn't look all that bad. I think I'd try just pressing it down before taking more drastic action.

Now, the geometry may be such that when the neck/fretboard is pressed down enough to make the fretboard extension straight, a small tapered gap may remain under the fretboard. That is, the end of the fretboard extension presses on the top, but the rest of the extension doesn't make contact. If that's the case. put in thin tapered wedge to fill the gap.

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Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion


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 Post subject: Re: Fretboard bowing
PostPosted: Thu Aug 30, 2018 11:53 am 
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Joined: Wed Jan 04, 2017 1:30 pm
Posts: 15
Thank you all. I laughed when I read the comment about John cranking down on those neck joints. I have watched hours of John's very helpful videos and I was surprised to see that the first time. So it does give one some confidence that the area can take a bit of pressure. I think based on the help here I am going to try and set the neck and see how it goes. I did clamp it together last night and it seemed to hold up just fine.

I will post a picture when done.

Again, thanks for the advice. I really appreciate it.

Dave


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 Post subject: Re: Fretboard bowing
PostPosted: Thu Aug 30, 2018 12:07 pm 
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Joined: Wed Aug 13, 2014 12:14 pm
Posts: 1162
Even if you don't meed a lot of the information this time, there is always next time.....

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When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion


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