Fretboard cracks

Construction and repair of Classical Guitar and related instruments
Simon Booton-Mander

Fretboard cracks

Post by Simon Booton-Mander » Sun May 13, 2007 8:46 pm

Hi All,
I have just purchased a guitar from e - b a y, for very little money. The reason it was going cheap was that it had two minor cracks in the fretboard close to the 12th fret, but does not affect playing.

My question is: what can I do to prevent the cracks getting worse or more appearing?

The fretboard is Ebony by the way.

Simon.

jfdana

Post by jfdana » Sun May 13, 2007 9:34 pm

Most likely a sign of too little humidity. If the guitar is worth it, a good repair person should be able to make the cracks vanish with some ebony dust and CA or the like. Although the cracks could stem from insufficiently dried ebony in the 1st place (unlikely). I would let someone who knows what they're doing (unlike me) have a look.

JD

Dan Kellaway

Post by Dan Kellaway » Mon May 14, 2007 1:44 am

Go to the hobby shop and buy some of the thin cyanoacrylate[superglue /CA] that they use for model building. Brands such as Hotstuff or Zapp are common in Australia.
Next get some white freecut sandpaper , one sheet of about 220 and one of 400.
Using a small square of 220 sand the timber across where the cracks are until the cracks are full of ebony dust. Then apply a small amount of CA into the crack and sand again quickly while the glue is still wet. Try not to get on your fingers.
The result will be a slightly filled crack plus a bit more dust.
Keep repeating this using unglued parts of the sandpaper until the crack is full and finally sand all the mess away leaving a flat surface. Also try not to get it on the frets but if you do then carefully scrape that off without taking any fret metal off. A stanley blade or scalpel can be used with care here. If you get a big build up on the board you can get a flat piece of wood narrow enough to pass between the frets and attach some of the 220 onto it with double sided tape. This will be an accurate sanding block and that way you won't get a scalloped fingerboard.
Then sand with the 400 until the bigger scratches from the 220 are gone.
At that stage I usually apply a paste that I make by melting grated beeswax into gum turps. This fills the pores of the wood with beeswax.
Then you can polish the wood and frets with a soft cloth and Brasso which is a very good fine polish that I also use for buffing up lacquer.
If you don't use the beeswax first the brasso will soak into the pores of the ebony and dry as a white powder which is hard to remove at that stage.
If you are doing this over the body it's a good idea to tape around the edges of the fingerboard with masking tape and mask the rest with paper or preferably cardboard or leather.
If all this gives you the heebie geebies then take it to a luthier but it's not that hard.

Simon Booton-Mander

Post by Simon Booton-Mander » Mon May 14, 2007 7:29 am

Hi Hemiola,
Would it not be better at the first sanding stage to use a spare piece of Ebony to create the dust and thus save the fingerboard from thinning, be only a little?

Dan Kellaway

Post by Dan Kellaway » Mon May 14, 2007 8:07 am

You could do that but the amount you sand is negligible and the colour match will be the closest if you use the board itself. I would be surprised if you could notice the amount sanded and in most cases the crack will become invisible using the method I described.
Hope that helps.
Cheers,
Dan

Simon Booton-Mander

Post by Simon Booton-Mander » Mon May 14, 2007 8:34 am

Hi Dan,
here is the spec of the guitar. It cost me £25 +£10 postage. So it might be worth me having a go.

Solid Spruce ‘AAA’ Top
Marbled ebony back & sides
Traditional fan bracing
Rosewood edge binding
Top & side wood purfling
Sapele neck
Ebony fingerboard
Rosewood 12-hole tie bridge
Rosewood headstock fascia
Inlaid Wooden Rosette

Dan Kellaway

Post by Dan Kellaway » Mon May 14, 2007 12:03 pm

Hi Simon,
Sounds like you did very well there and yes if you are confident you really can't get into too much trouble.
Just be very careful with that superglue. The other thing I forgot to mention is that you have to avoid getting it in your eyes as a random squirt could result in blindness and try not to inhale the fumes as well.
The thing with that glue is that when it combines with wood dust there is a hyperthermic reaction sometimes and it goes off with a little puff of smoke. Too much of that isn't good because it leaves kind of bubbles in the fill so you avoid that happening by making sure there is enough glue flooding the crack and then sanding while it's wet.
Really you'll get the hang of it once you give it a go.

Simon Booton-Mander

Post by Simon Booton-Mander » Mon May 14, 2007 10:39 pm

Hi Dan,
Is Gum Turps just turpentine?

Simon Booton-Mander

Post by Simon Booton-Mander » Wed May 16, 2007 10:24 am

Hi Dan,
The CG arrived this morning. The problem is quite obvious, the Ebony used for the fretboard was not seasoned enough and subsequently shrunk so much that the fret bars are now pushing through the fretboard side binding and the cracks have worsened. Ah well the bridge and the machine heads are worth the £24 paid.

Dan Kellaway

Post by Dan Kellaway » Wed May 16, 2007 3:09 pm

Hi Simon,
Gum Turps is the turps that artists use to mix with oil paints.
Now it sounds as if the fingerboard is a write off. Perhaps you need a professional opinion on that. If so there is a fairly simple solution which is to buy a prefretted fingerboard from Stewart McDonald and fit it. To do this you have to make sure to get the right scale length which will most likely be 650mm. However you must measure the distance from the nut to the middle of the twelth fret which has to be exactly half the scale length.
If you go down this track I can advise you how to get the old board off and how best to fit the new one.
You should perhaps tune it up first to make an evaluation of the tone and to see if it's worth fixing it up.
I think the prefretted board will be $50 or $60 but you should also check on that.
It might be worth the trouble and the next thing you know you'll have begun to be a guitar repairer which wouldn't be all bad.
Let me know what you decide.
Cheers,
Dan

Simon Booton-Mander

Post by Simon Booton-Mander » Wed May 16, 2007 5:21 pm

Hi Dan,
here are some pic of the CG. You can see how bad it is, but I am going to make it a project. I went to the website you mentioned to see the fingerboards. Am I correct in thinking I will have to buy and fit the fret wire myself... how exciting!
You do not have the required permissions to view the files attached to this post.

User avatar
James Lister
Luthier
Posts: 7361
Joined: Fri Nov 17, 2006 3:53 pm
Location: Sheffield, UK

Post by James Lister » Wed May 16, 2007 9:18 pm

Hi Simon,

Looks like you've got yourself a nice little project there - hope you're handy with your woodworking tools!

You might like to check out Touchstone Tonewoods - I think they also carry slotted fingerboards, and they're a bit closer to home.

http://www.touchstonetonewoods.co.uk/

James
James Lister, luthier, Sheffield UK

Simon Booton-Mander

Post by Simon Booton-Mander » Wed May 16, 2007 11:03 pm

Hi James,

that is wired, I was logging on to pose the very question, "does anyone know of a good UK CG parts dealers. And there you are with the very answer I need. I thought that a new fingerboard was going to be more expensive, but I was pleasantly surprised.

What specialist tools am I likely to need?

Thanks James.

Dan Kellaway

Post by Dan Kellaway » Thu May 17, 2007 12:15 am

Hey Simon,
You could still fix the one you've got though you'll need to pull out the frets that are pushing out the binding and the edge of the board like that. You then file the tang off so that it will fit back without impacting on the binding, but of course repair the wood before re fitting.
Pulling out frets is usually what sorts out the amateur from the pro. What you need is a set of very fine jawed electrical end nippers or buy one from a luthiers supply but I think electrical ones are better and cheaper.
Carefully squeeze these very thin jaws in at one end and then work across without any pulling motion. This means that the jaws support the wood as they slightly lift the fret, reducing the tearout. Then go back and carefully rock the tool to lift the fret further out. Once one end is clear the fret will come out more easily. If you get some tearout which is very likely, particularly with ebony, don't sweep it away. Leave it in place and carefully push it back down flat, and before you do the next fret, run a line of that thin CA along each side of the slot. Do not sand this now. Wait till it's dry. If you are doing the whole lot, then sand it all at once with a sanding board that you prepared earlier. A good size for this is 10" by 2", using something nice and hard like rock maple, machined perfectly flat on the electric planer[the belt sander is not quite good enough for this], and then with 100grit freecut[the white stuff] applied with double sided tape.
If only doing more localized areas then use a smaller block such as 2"by2".
Because of that binding on the edge of the fingerboard there is a complication with filling the fret slots with glue and dust. You can either make up a tool for digging this out[rather like a saw tooth that can be made out of an old pen knife by filing to slightly thinner than the slot for about double the slot depth, and then with a round file such as a chainsaw file take a radius out of the end to create a hook with a very fine chisel end][I'll post a photo of this later],or simply use a fretslot saw and cut through the binding like an unbound board. This is easier but looks a bit unprofessional.
I'll go into the rest if you choose this route but if you are going to replace it anyway:
I noticed from the photo that the soundboard is cracked under the end of the fingerboard. You should get a mirror in there to see how far that crack goes, probably all the way to the headblock. This will have to be repaired too if you take the fingerboard off. It will open up more once the fingerboard comes off and will need a fillet. This would also indicate that the soundboard was put together with high humidity. Have a good look at the rest of it, particularly around the edges of the bridge and around the outer edges of the lower bout. Check inside with a mirror also. If there is any cracking beginning anywhere else then I would definitely be doing the superglue job rather than the new board which is very much more work.

By the way if you email Stew Mac I think you'll find they sell prefretted boards. I know at least one luthier who uses them on all his guitars for quite a time saving but it was a few years ago and perhaps they no longer do it.
More later.

User avatar
James Lister
Luthier
Posts: 7361
Joined: Fri Nov 17, 2006 3:53 pm
Location: Sheffield, UK

Post by James Lister » Thu May 17, 2007 12:58 pm

Hi Simon,

Personally I'd go for replacing the fingerboard - but repairing it should be possible. The biggest problem (I think) in replacing a fingerboard is getting the finish clean where it meets the soundboard. It is possible to remove a fingerboard with heat and a knife - but it's quite tricky and there's a risk of damaging the soundboard and neck. The alternative it to plane it off, but you need to find a way of holding the guitar very securely, and you need a decent, sharp plane for the ebony. You'll need to use a chisel at the nut end of the fingerboard where the plane can't reach. (Maybe a repair isn't such a bad idea after all!).

Anyway, I'm sure Dan and I (and others) can help more when you've decided which way to go.

James

P.S. Of course you could always pay a luthier to do it for you - if the guitar sounds good, you would still have a bargain.
James Lister, luthier, Sheffield UK

Return to “Luthiers”