archtop guitar center seam separation

[Ernie Miciak]

Hi

I built a D'Angelico New Yorker copy from Tom Ribbecke's plan (via Luthier's Mercantile) about 12 years ago.  It has since developed a center seam separation on the x-braced sitka top.  It's about 1/8" wide.  I would sure appreciate any suggestions on repairing this thing. I tried a wood epoxy filler (the light stuff in the pix) but not happy with it. Have read about the double blade knife for removing a uniform width of wood then inlaying a new piece of sitka. Any thoughts?

Ernie

[Ned Knepp]

This looks to me like the glue joint failed on this top. What type of glue did you originally use for the joint? Also, how long did the guitar last before this separation developed?  

  If it lasted for years I wouldn't necessarily try to fill it until I knew that I couldn't close it up first. I you should remove the filler as completely as possible then explore how you might get it to close up again. Hydration is the first thing that comes to mind. Hydration and patience.  I would do this first then see if it's possible to clamp the crack together with new glue. 

[Ernie Miciak]

Hey Ned, thanks for the speedy reply.  Apparently this is a common problem even on the original D'Angelicos.  It took about 10 years for this to start developing in the winter of course (Alberta).  Last year the separation was approx. 1mm and it closed up.  I've been negligent about keeping the humidity in my instruments up but will have to change my ways. Anyway this year it opened to what you see (approx. 1.5 mm at it's narrowest to 2.2mm at its widest). Fairly ragged grain separation over the x and headblock.  Original glue was Titebond. 

I spent yesterday aft removing the epoxy and now looks like the pic. Would you use titebond again? And then I'd be obligated to keeping it at he rehydrated rh.  This would be fairly high if this garbage bag technique were used.  And if it did close do you then force it open enough to get glue in the line?

[William F.Eden]

I would take Ned,s advice and put it in a garbage bag and hydrate it for two weeks or so. Bill.............

[Ernie Miciak]

Thanks for the reply William.  What a great site.  For us in the boonies its a real boon.  I haven't heard of this garbage bag trick, could you expand on it a little?

[William F.Eden]

  I am sorry I thought every one new about the Garbage bag trick .You get a larg G.B and put the guitar in along with a small plastic bag with a wet rag inside the small bag leave the sm. bag open.I try and use hot water if I am in a bit of a hurry and change the water every day. In your case because it is an arch top I would suspend it up off the bottom of the bag with two blocks face down and put the wet bag in under it and close the bag up tite.I hope this is of some help to you. And I would use Sp. glue  for the glue. P.S. others may have a different way but this is my way and it works for me .Good luck on your project Bill............

[Ernie Miciak]

Thanks again Bill, any problems you can forsee using this technique on a guitar with wood (maple, walnut) bindings?

[William F.Eden]

I would not think so as the  Lacquer finish should protect that part of it. Put the water bag in the center between the   F. holes. Just keep an eye on it as it should take less time using the hot water .Bill................

[Ernie Miciak]

Ok, I'll get back to you and let you know how it goes. e

[Jeff Highland]

I'm going to dissent from the rest of the guys

IMHO that crack is an indication that the top was glued to the rim at too high a humidity level. Subsequent drying led it to shrink while being restrained by the the rims and opened up the crack.

If you superhumidify it now and manage to close and glue the crack, It's just a timebomb waiting to fail again when it gets back to normal humidity levels.

I'd be splinting the crack at low RH

[Ernie Miciak]

Hi Jeff, thanks for taking the time to respond to mty dilemma.  I have to agree, I think the opening is too wide and it will just split again.  I asked an old violin restorer friend of mine about his approach to humidification of a shop full of high end instruments and he tended to shrug it off saying that most of these instruments had acclimatized to our prairie conditions and that no matter what you do you'll end up doing some regluing.

What are your thoughts on making the split a uniform width?       

[Jeff Highland]

I have no experience in splinting yet, the climate here is pretty good for instruments.

I'd be doing it like Ned suggests with a wedge shape. If you cant do it in one length , perhaps make the joint under the bridge.

[Ned Knepp]

Before I forget, That's a nice looking guitar, Ernie.  

 Bill's method for hydration should work fine. I prefer to keep the instrument in the case, laying down with a ziplock baggy to hold the sponges. On Archtops, I usually make up a wire hanger  then poke some holes in the top half of the bag, above the level of the sponge. This keeps the bags where I can easily get to them but still places them inside of the guitar's body.  I use a big syringe to fill the sponges after I get them inside of the guitar and only open the case to refill the sponges. It's can be a trial of patience to get an instrument re-hydrated but it usually pays off.

  I use hot hide glue for most things but I might use titebond again if I was sure I could get it clean enough to insure it would hold. I've read that D'Angelico's seem to be prone to this problem too and you should probably formulate a plan to install some cross grain support once it's repaired.  

  With that in mind, once you are ready to make your repair, you might want to consider removing the back to work inside of the guitar. One of my concerns with a gap this wide is that you have compromised the top's attachment to the X brace too. If you used the same glue for the braces you need to double check that they are not suffering glue failure. Opening the guitar would allow you to check that the bracing is tight as well as give you easy access to the repair to install some support for the joint. 

  In my opinion, splinting a crack on a flat top is much easier than on a archtop. The curvature of the top can be a problem but if the body is open you can make a splint that is as wide as you need to fill the crack but much deeper so you can insert it into the crack then remove the excess material once it is dry. On a crack that is potentially this long, I would do it several pieces over the length of the body, all from the same length of spruce. In other words, I don't think you need to make a single splint that is the length of the crack AND the depth of the arch, Just one that is the total length of the crack which can be cut to different lengths and fit into the crack. ( remember that the arch may require some angle cuts on the ends of the splints if they are fitted in this way.

  If you need to splint the top I think it is best to bevel the crack and then bevel the sides of the splint. In this case it may stand proud of the top on both sides but it can be pared close to the top and scrapped level with the surfaces. I have used both a small tapered triangular file and a small "V" chisel. I have had some cracks that dragging one corner of the file seem to work best but over all both worked fine. Just don't make the vee so deep that you are actually widening the crack.

   Anyway, right now you are at the stage where I spend a lot of time looking and thinking. As the original builder, you have an advantage in determining how to proceed..