Refretting and repositioning the neck on a neck through

[Fynn]

I'm going to work a bit on my bass soon, and I just wanted to do a sanity check by asking here if my methods would be okay, or if I'm forgetting something obvious.

First I have to do a complete refret, because I wanted to put a radius on the fretboard.
My to do list would look something like this:
1. Remove strings
2. Loosen truss rod completely
3. Pull out current frets with fret tongs
4. Fill the fret slots with strips of wood and woodglue
5. Sand a radius into the fretboard with a radius sanding block
6. Cut fretslots anew
7. Put fretwire in
8. Level / crown the frets


Then I wanted to slightly shift the position of the bridge. It's a Kahler bridge, so there is a huge chunk of wood taken out of the body, right where the bridge is. My plan was as follows:
1. Remove bridge
2. Fill screwholes with toothpicks and wood glue (not sure about that part, but it sure has worked in other situations before)
3. Level the side of the cavity which the bridge would shift away from
4. Glue a piece of scrap wood onto that side
5. Recut the cavity to the correct size
6. Redrill the holes for the bridge
7. Attach the bridge


I'm not so sure if what I'm going to do with the bridge would actually work as intended. I figured there's no reason to fill the whole cavity back up, as I only want to shift the bridge a few mm (I will measure how much exactly, but it shouldn't be that much). Worst case scenario I would have to cut a bigger chunk out of the wood and then glue a big piece into it, but I'm obviously trying to avoid something like that. The bridge would cover up what I'm currently planning, so I wouldn't ruin the look if my plans actually go accordingly.
Another thing I'm wondering about is if it's really fine to fill the holes with toothpicks, because toothpicks are of course way softer, than a dowel for example. But I thought it was fine, since the bridge doesn't pull that much on the screws anyways, since most of the force is going sideways and not pulling up on the bridge.

I guess also part of what I'm worried about, is how flat the side of the cavity would need to be to properly glue another piece of wood onto it. I know that wood glue is incredibly strong, but how flat does it actually have to be, to not risk it breaking after a while?



Please tell me if I'm missing something, or if there's maybe a better way to do this that I haven't thought about.

 

[Beej]

Is it a double acting truss rod? If it is, then put the neck in a slight backbow (flat, but a bit tight into backbow) before defretting it. I always heat the fret before removing it, I use a soldering iron to warm it up, as it helps the wood fibers to give way around the slot.

If you are refretting, then there's no need to fill any slots and recut them, just clean them up the best you can. For a dark wood board, when I refret, I pull each fret and then glue back any chips before I move onto the next fret. I use a medium viscosity CA glue to do this so that it's not so messy.

For the radius, you can use a radius block to get the general radius, but they are fussy to use on a retrofit - I'd like to see some pics of the instrument before other recommendations. Sometimes flat boards when radiused will change the appearance of the neck quite a bit, so it's good to check this so you can predict it. A radius block will easily sand a longitudinal curve into a fretboard unless it is supported on rails along both sides of the neck (prevents pushing too hard in the middle).

 

[Bruce Johnson]

I'm going to work a bit on my bass soon, and I just wanted to do a sanity check by asking here if my methods would be okay, or if I'm forgetting something obvious.

First I have to do a complete refret, because I wanted to put a radius on the fretboard.
My to do list would look something like this:
1. Remove strings
2. Loosen truss rod completely
3. Pull out current frets with fret tongs
4. Fill the fret slots with strips of wood and woodglue
5. Sand a radius into the fretboard with a radius sanding block
6. Cut fretslots anew
7. Put fretwire in
8. Level / crown the frets


Then I wanted to slightly shift the position of the bridge. It's a Kahler bridge, so there is a huge chunk of wood taken out of the body, right where the bridge is. My plan was as follows:
1. Remove bridge
2. Fill screwholes with toothpicks and wood glue (not sure about that part, but it sure has worked in other situations before)
3. Level the side of the cavity which the bridge would shift away from
4. Glue a piece of scrap wood onto that side
5. Recut the cavity to the correct size
6. Redrill the holes for the bridge
7. Attach the bridge


I'm not so sure if what I'm going to do with the bridge would actually work as intended. I figured there's no reason to fill the whole cavity back up, as I only want to shift the bridge a few mm (I will measure how much exactly, but it shouldn't be that much). Worst case scenario I would have to cut a bigger chunk out of the wood and then glue a big piece into it, but I'm obviously trying to avoid something like that. The bridge would cover up what I'm currently planning, so I wouldn't ruin the look if my plans actually go accordingly.
Another thing I'm wondering about is if it's really fine to fill the holes with toothpicks, because toothpicks are of course way softer, than a dowel for example. But I thought it was fine, since the bridge doesn't pull that much on the screws anyways, since most of the force is going sideways and not pulling up on the bridge.

I guess also part of what I'm worried about, is how flat the side of the cavity would need to be to properly glue another piece of wood onto it. I know that wood glue is incredibly strong, but how flat does it actually have to be, to not risk it breaking after a while?



Please tell me if I'm missing something, or if there's maybe a better way to do this that I haven't thought about.

About the neck:

Like Beej said, I dont see any reason to fill the slots with wood, then resaw them. You should be able to pull the frets, reshape the fingerboard to the new radius, and then resaw the slots to get them to full depth at each end. Then finish sand the fingerboard and refret it.

You don't really need a radius sanding block to make a radiused surface on a fingerboard. That's trainer wheels. You can reshape the radius with a big flat file, a big flat sanding block and a radius gauge and straightedge. Work slowly and keep checking it.

About moving the bridge:

I'm assuming that you've already checked to make sure the saddles will have enough range of travel in the new position to get the intonation correct? Why do you want to move the bridge?

Filling the screw holes with toothpicks and glue is a quick field repair, not the best way. The better way is to drill the holes oversize and glue in birch dowels.

To fill the edge of the bridge pocket, yes, you should clean up the edge of the pocket to make it straight and smooth. Then fit a piece of wood so it glues in tightly with no gap.

 

[Fynn]

It is a double action truss rod, so I can definitely give it some back bow if that helps.
I thought that maybe it would better to fill the slots in before I put a radius on the neck, because I feared that it would destroy the edges of the fretslots when I sand over them.
I specifically bought a long radius sanding block (50cm, with the neck being ~67cm), so that there would be minimal chance for me to mess it up. I understand that it would also work just fine doing the whole process by hand, but I just don't trust myself to do that. I think I'm fine with training wheels, at least for this one.

I'm not quite sure why sanding a radius into the fretboard would change the appearance of the neck though? If you tell me what exactly you're looking for, I could send a picture. But I'm not too horribly concerned about the looks anyways. I mostly care about it playing right, and about the frets sitting correctly. The wood is wenge, and the piece I used doesn't really look very different when you sand it down, because the grain is pretty tight. It's quite dark with the finish that I use and looks almost more like black ebony, without much contrast in the grain.


I wanted to reposition the bridge, because the slots where the strings are hooked, are not centered correctly. I can move the saddles, but I can't change the position where the strings are actually attached. And since it's offset by quite a bit, the string has an ugly angle. This might not even be a problem technically, but since it's a whammy bridge, I don't feel quite comfortable leaving it like that.
I would also take that opportunity and clean up the edges of the bridge cavity, but that's of course just aesthetics.

I should probably use dowels for the screwholes then, but they would have to be quite small, since theres not a lot of wood around that area to begin with.

 

[MPU]

You can’t destroy the fret slots when sanding. You may have to saw them deeper but they will not be destroyed.
The neck appearance will change a bit. The fretboard will get thinner on the edges when radiusing a flat fret board. How much depends on the radius. The neck will feel a bit thinner.
It looks like the G-string is hooked at the bridge and E-string goes straight. If you reposition the bridge with same string spacing you will have both outer strings a bit hooked and inner strings almost straight. That will look better for sure. Only way to get straight string paths with that bridge is to widen the string spacing. Whether that is possible or not depends on the neck width and how far from neck edges you want the outer strings.

 

[T_Bone_TL]

If the string spacing remains the same I'd consider a bit of filing on the outer two slots to ease the bend into the saddles. Nothing drastic, mind you, but letting the string get from the anchor to the saddle without a double bend from the upper edge of the anchor slot as seen in the G string now.

 

[Fynn]

I realized that the fretboard would get a bit thinner at the edges, and that should be fine. It's thick enough so that I don't have any worries about that.

I have a little bit of extra room on the E string side, so I would very slightly widen the string spacing too. But yes, the plan was to just overall even it out a bit, so the A and D are close to straight, while the E and G are at a slight angle.

I'm not sure I want to file away at the bridge, but I'll keep that in mind, if repositioning doesn't have as much the desired effect as I hoped for

 

[Beej]

I know you said you'd rather move it without filling the cavity, but if you do fill the cavity, you can either fill it with something contrasting or try to match it for a clean look. You got this far without a router, but imagine what you could build with a router. If this were me, I'd make a template, rout a new cavity that would hide this one, fill it with a block and then rout a new cavity in a location that would permit opening up the string spacing closer to the edges of the board. That would let everything line up nicely.

 

[Fynn]

I know you said you'd rather move it without filling the cavity, but if you do fill the cavity, you can either fill it with something contrasting or try to match it for a clean look. You got this far without a router, but imagine what you could build with a router. If this were me, I'd make a template, rout a new cavity that would hide this one, fill it with a block and then rout a new cavity in a location that would permit opening up the string spacing closer to the edges of the board. That would let everything line up nicely.

View attachment 5438746

I'm not quite sure what you mean with that. The frame of the bridge is recessed into the body, and in addition to that there is a huge cavity underneath the tremolo mechanism to make it float freely. What I meant was that I didn't want to fill in all of that cavity underneath the tremolo, because I would have to carve 99% of that out again anyways.
When I move the bridge I would have to widen the outline of the bridge because of the recess it's in, and to make that look cleaner I planned on simply gluing a different colored wood all around the bridge as a sort of frame.
But everything that is underneath the bridge, you can't see anyways, which is where my confusion with your comment came from.

Or maybe I just misunderstood what you were trying to tell me. I am trying to not make it look too ugly either way haha

 

[Beej]

I mean you could make a simple square routing template like this and rout out a fixed cavity that would hide the previous one.

You could then insert a block just down say 6mm. Then make a new template for the bridge itself and recess the bridge in the new location. You can make a routing template for any geometric figure (other than curves) by making small blocks that fit around the object like this:
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After you pull the item out, you can then rout inside, remove the temp blocks and you have your routing template. This is a very quick and easy way to make custom routing templates. If you had a router and a top bearing bit like this, you could be done in no time.

 

[Fynn]

I very much appreciate all the help, but I'm gonna change the plan now. I have been doing some measurements and thought about it a bit more. Up until 5 minutes ago, I didn't even know why the bridge wasn't in the correct place. I don't fully remember how I built the bass, but I do remember that I put the wings on after gluing the neck to the center piece of the bass. Somewhere in the process of joining the neck to the centerpiece, I have glued the neck in slightly crooked. The neck is essentially tilted downwards (to the right when you look at the bass standing up) ever so slightly. Over the entire length of the instrument, that tiny angle puts the strings in the wrong position at the end where they meet the bridge.

The white lines are from one corner of the fretboard all the way down to the corner of the center piece. The red lines outline the neck and the centerpiece seperately. Might be difficult to see, but the overlap of the white lines and the red lines of the neck, shows how the neck is crooked (in this picture the neck is bent upwards). This would explain why the saddles of the bridge have to be moved towards the one side so far, and are not centered correctly.

Instead of redoing the route for the bridge, I think maybe it would be best to just remove the neck and put it in straight. I don't know how exactly I'm going to do that, but that's essentially how I want to fix that now.
I'm not sure if I should make a new post for that, but I definitely appreciate the help you guys provided and will keep the things in mind for the refret!

Edit:
So far my plan would be to cut off the wings, cut the neck from the center piece, try to get the neck straight in with the center piece (maybe remove some of the wood from the butt of the neck and glue a level piece in it's place to keep the length the same), and then reattach everything.

 

[T_Bone_TL]

Tends to work better if you stay in one thread so people are not having to go off to multiple threads to get context on the fixing/building/rebuilding of one instrument, usually. Or coming in not having read "the other one" and re-stating a bunch of stuff you've already hashed out.

If you want to change the title and it's past the point you can edit it, you can flag ("report") the first post and request a moderator to change that for you (I think that's the right procedure.)

Do you recall what kind of glue you used on the neck joint? Might be possible to get it apart with heat rather than cut it off, based on past threads. Also, why cut the wings off?

 

[Fynn]

Tends to work better if you stay in one thread so people are not having to go off to multiple threads to get context on the fixing/building/rebuilding of one instrument, usually. Or coming in not having read "the other one" and re-stating a bunch of stuff you've already hashed out.

If you want to change the title and it's past the point you can edit it, you can flag ("report") the first post and request a moderator to change that for you (I think that's the right procedure.)

Do you recall what kind of glue you used on the neck joint? Might be possible to get it apart with heat rather than cut it off, based on past threads. Also, why cut the wings off?

I used original/classic titebond for the entire thing.
I wanted to cut the wings off, because to me that seems to be the only way of removing the neck, without having to cut the neck into pieces. At least I don't have a better idea at the moment.
I would cut off both the wings, which would allow me to cut the center piece off the neck from the side. At least that would leave the neck in one piece, and then I would just have to get everything back together after fitting it correctly.

I'm not too experienced with wood working, but the neck is held in place with glue from three different sides, and it's quite deep, so I would imagine that heat doesn't work. But I really don't know

 

[T_Bone_TL]

Heat weakens Titebond. Injecting steam (pick up a "coffee appliance with steam wand" cheap at the thrift store, attach a hose, attach a needle (as for filling basketballs, etc.), possibly drill some tiny holes) and/or inserting a heated thin blade (palette knife or puttyknife are typical) are ways to get heat in deep.

Better pictures of the whole thing might lead to better suggestions specific to it.

If you're already thinking to cut off the wings and cut out the neck, making a whole new center block rather than trying to reassemble it would probably be more productive. But you might not have cut the neck out.

 

[Fynn]

I'm not sure what would be the best/easiest way to go about this really. I imagined cutting the wings off was easiest. If I were to remove the neck with steam, what would be the best way to make the neck fit in straight? And wouldn't that also risk weakening the glue on all the other joints nearby? Would that be a problem or does the glue just dry again, if you leave it be for a bit?

 

[1n3]

I think it would be much easier to re-position the bridge than to re-position the neck.

Also, I notice that the string spacing of the bridge saddles is narrower than the spacing in the notches in the trem bar. I assume the saddle spacing is to accommodate a narrower fingerboard, but while that's the case, you won't get a straight pull over the saddles; there will always be some sideways angle. But you could at least center the saddles relative to the bar so that those angles are symmetrical.

I've never dealt with a bass trem bridge, but it looks like other (later ?) versions had separate claws for each string, which would allow straight pulls for all strings.

 

[Fynn]

I think it would be much easier to re-position the bridge than to re-position the neck.

Also, I notice that the string spacing of the bridge saddles is narrower than the spacing in the notches in the trem bar. I assume the saddle spacing is to accommodate a narrower fingerboard, but while that's the case, you won't get a straight pull over the saddles; there will always be some sideways angle. But you could at least center the saddles relative to the bar so that those angles are symmetrical.

I've never dealt with a bass trem bridge, but it looks like other (later ?) versions had separate claws for each string, which would allow straight pulls for all strings.
View attachment 5441604

The one with the adjustable claws is the more expensive modern version. The one I have is a cheaper variant, which is more similar to the bridges they made back then. I chose the cheaper one, because it was only 420€, while the more expensive one is about 630€. I wasn't willing to pay that much more, just for that essentially.
I understand that the strings would never go completely straight, but that's not my plan anyways. I just want to even it out. The angle on that G string is worryingly steep.
I also understand that the easiest way would be to reposition the bridge, but that would also put it at an offset on the body.

This is the first and only bass (so far) I've ever built (unless you count my parts P bass haha). I made plenty of stupid beginner mistakes, and ruined a few pieces of wood too, but I still kinda want to do it the right way. If I mess up even more and the neck becomes unusable because of my stupidity, then I'm going to build a new one.
I'm not asking for the easiest way out of this situation, but rather the easiest way to fix my previous mistake and redo it properly.

 

[Beej]

@Fynn have you put a straightedge down the side of the neck over the body to determine if the neck is actually aligned crooked? From the pics, I can't tell. The spacing of the neck block against the wings looks correct and even from the end of the fretboard down to the butt. I wonder if the neck itself has a slight arc to it from nut to end of fretboard? Placing two straightedges down either side of the fretboard will tell you how far off the center the neck sits from the body. I'm not wording this well - I'll see if I can get a picture...

 

[Beej]

Found one - this is what I mean. If you lie straightedges down the sides of the neck, you can then determine where the actual centerline of the neck is, and see if it is aligned with the centerline of the body or not.
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[Fynn]

@Fynn have you put a straightedge down the side of the neck over the body to determine if the neck is actually aligned crooked? From the pics, I can't tell. The spacing of the neck block against the wings looks correct and even from the end of the fretboard down to the butt. I wonder if the neck itself has a slight arc to it from nut to end of fretboard? Placing two straightedges down either side of the fretboard will tell you how far off the center the neck sits from the body. I'm not wording this well - I'll see if I can get a picture...

The neck definitely isn't 100% even, since I've worked on it with my hands, but it is definitely not crooked like that. That's why I have made this picture with the lines. The red lines (which you can't fully see on the cropped version I posted here) are drawn digitally from one corner of the nut, to the other corner on the same side. It goes pretty much straight along the edge of the fretboard. I did the digital picture only to double check, because at first I used a piece of string that I placed on each of the corners that I also checked on the digital version. I did that a couple of times, checking again and again, and always came to the same conclusion. When I go from corner of the nut to corner of the center block, then it looks the way it does with the white lines on the picture I posted.
I have also put a steel ruler on the sides of the fretboard and checked that way. It's definitely straight enough to not cause this problem.