Help with replacing soundboard please.

Steve in Kent · May 4, 2017

Right,

I have finally taken the plunge and decided to have a go at replacing the damaged soundboard of my Lanikai LU8.

First time I have attempted anything like this.

I have removed the soundboard, but left it under the fretboard.

I was planning to cut a slot in the top and fit it around the fretboard, or should I try to remove what is left of the soundboard?

I was going to glue a piece of left over spruce under the existing fretboard/what's left of the soundboard, leaving a 5mm shelf to glue to.

Will this work OK?

So far it now looks like this.

I also need to replace one of the cross braces(?)

I have got a spruce soundboard, 2 piece and glued, ready to sand down from 3mm to 2mm before fitting.

I am also replacing the binding.

Any advice would be appreciated.

To start with,

What is the best way to get the soundboard to the correct shape, (couldn't get the damaged one off in one piece)?

Do I get the board sanded to 2mm before or after cutting it to the correct shape?

Regards,

Steve

Michael Smith · May 4, 2017

Most people would remove the fretboard but I don't see why what you are doing won't work. Removing the fretboard can have it's own set of horrors.

sequoia · May 5, 2017

The only time I have replaced tops I removed the fretboard. Not exactly a nightmare, but a test of patience. Easy enough. I suppose one could get around this, but there are problems. One, your top is not anchored to the neckblock and two, you have a weak (and visible seam) around the fretbaord and three, how are you going to sand your sides flat to accept the top?... Yes, your new top will have to be properly braced... 2mm sounds about right. Good luck!.... P.S. Just remove the fretboard and things will go easier.

Steve in Kent · May 5, 2017

Thank you for the fast responses.

I have tried to remove the fretboard, but it has been removed before and I can't even turn either of the two screws holding it in.

I think they have been glued and screwed.

I have managed to remove all the soundboard from under the fretboard, so can slide the new board under it.

Hopefully the top is a already flat so I will not have to sand the sides flat, plus I do not want to remove any material as I have no way of redoing the offset where the binding has to go.

Would I be best to cut the board to shape before having it sanded down to 2mm?

Regards,

Steve

sequoia · May 6, 2017

Steve in Kent said:
Would I be best to cut the board to shape before having it sanded down to 2mm?

Regards,

Steve

If I understand your question, cut your top slightly larger than the body and sand down to 2 mm. Sand body edges with kerfing falt. Glue top on. Then bring down the top along the sides flush with the sides with sandpaper, plane, routher what ever. Once flush, sand and refinish sides and top. Done. I would guess you are not going to install binding.

Steve in Kent · May 6, 2017

sequoia said:
If I understand your question, cut your top slightly larger than the body and sand down to 2 mm. Sand body edges with kerfing falt. Glue top on. Then bring down the top along the sides flush with the sides with sandpaper, plane, routher what ever. Once flush, sand and refinish sides and top. Done. I would guess you are not going to install binding.

Excellent, thanks.

So I should leave about 3mm to 5mm around the edge of the top, glue it on then sand, (carefully), to the body edge.

The body had binding before, so I will have to instal binding again.

So I assume the final top sanding should be done with the binding in place.

I have bought some plastic blue abalone to fit.

Steve in Kent · May 9, 2017

I also want to replace the bracing, so do I use laminate, as were the originals, or go for something different?

Steve in Kent · May 18, 2017

Well,

I have cut around the soundboard to around 3mm to 5mm outside the body and had it sanded down to 2mm

I have bought some 6.5mm x 12.5mm spruce strip for the bracing which I will sand and cut to the required sizes.

But just wondering about what to use under the bridge, would some 6mm liteply be OK, or should I use something else?

greenscoe · May 18, 2017

An acoustic guitar may use a plywood bridge patch, but on a ukulele its usually either spruce or mahogany, quarter sawn, 2mm thick and with grain direction across the soundboard.

RPA_Ukuleles · May 18, 2017

It has been my experience that a more dense/stiff bridge patch can favor a tighter, more articulate string response, while a soft bridge patch material can favor a more mellow, lower tone response.

This is a generalization, and your mileage may vary.

Steve in Kent · May 18, 2017

Thank you for your replies, forgot to say that this is an 8 string so will have a lot more tension than a 4 string.

I have got some 3mm quarter sawn spruce too, which going from your replies would be better than the liteply.

Steve in Kent · Aug 25, 2017

Well,

Just got back into replacing the soundboard.

Anyone able to recommend a bracing pattern for an 8 string tenor?

Don't think I can copy the original as the top was laminate, and now it's going to be solid spruce.

Cheers,

Steve

Answered my own question, sort of.

Had a look at a few images and have decided to go with what looks like a fan.

Two straight across either side of the soundhole, and three fanning out to the lower bout.

Don't know about adding another 2 either side of the soundhole between the two straight across ones.

Steve

Steve in Kent · Aug 30, 2017

I've cut out the bracing strips, just need to scallop them, and sand the edges down.

How smooth does the underside of the soundboard have to be?

It's been through a sander to get to 2mm, so it's pretty smooth now, but not as smooth as the top is going to be after final sanding.

So, does it need to be as smooth as the outside is going to be?

sequoia · Aug 31, 2017

Nope. Rough on the downside is good. Better for gluing too.

Steve in Kent · Aug 31, 2017

sequoia said:
Nope. Rough on the downside is good. Better for gluing too.

Excellent, thank you for the fast response.

Help with replacing soundboard please.

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