Repairing a hairline crack in an ebony bridge...

[Dave]

I found and bought a '76 Guild D-50 yesterday. It looks nearly new, except for a fine hairline crack in the bridge thru the pin holes. It starts at the B (#2) string pin hole, and extends ~1mm past the low E (#6) hole. The bridge is attached firmly to the soundboard, there isn't significant belly (at least for a 33 yr old guitar!), and the bridgeplate/braces inside look fine. My guess is someone forced the bridge pins in too hard...

I'd like to get it stabilized so the crack doesn't progress any further and threaten the integrity of the bridge... but I would like to do it w/o removing the bridge. Someone over at Lets Talk Guild suggested running some slow cure super glue (CA) into the crack, and then following with some #400 sandpaper to smooth the surface afterwards. The cracks pretty tight along much of its length, so don't know how well the CA will flow into it.

I don't know if this is something I want to take on myself, or take it down to my tech...thought I would check here for any other suggestions/advice before deciding what course to follow.

Advice anyone?
Thx, Dave

[Greg Mirken]

This is not hard to do. Also not expensive if you want to let a pro do it. You'll need to use thin superglue, After pulling the pins and strings out of the bridge, put a couple of layers of paper towel inside in case you spill a drop down a pin hole. Don't use the bottle to apply drops of glue; carry them from the bottle to the bridge on a toothpick or something similar. To be safe, mask the top and only have the center portion of the bridge visible.Let your first applicatin sit for 15 minutes or so, then go back again to finish filling the crack. A touch with some sandpaper and you're done.

[Dave]

Thanks for the suggestions... particularly about maskng. I am sure I would have forgotten about that! Dave

[Jeffrey L. Suits]

I wonder if jacking up the top a little from the inside, to open the crack, might help.

I saw a good tool for transferring microdrops of superglue, in Micro-Mark's catalogue: it's a needle with half of the eye cut off, stuck in a handle! Been meaning to make one...

Won't thin superglue just wick into a wooden toothpick?

[John Cadd]

I bought some bottles of superglue [pound shop] and they put in a thing to apply drops separately.
It was the same plastic as the bottle.If you think of a glass tube heated then suddenly stretched out.You get a very fine long point.Only this was plastic. Try using some polypropylene .That`s almost glue proof.

[Dave]

Thanks all for your suggestions. Dan, I have looked inside with a mirror and light, and the bridge plate and all the bracing look good. The rosewood bridge plate shows little wear from the ball ends of the strings... from what I can see the edges of the pinholes look crisp and clean (just a small splinter out between the two of the holes, that appears to be breakout from when the holes were drilled. There is less bellying of the top than on any of my other 35 yr old Guilds... this guitar really seems almost unplayed.

When sanding after applying the CA, would you suggest lightly sanding the entire top surface of the bridge... or just spot sanding the glued area of the crack (wish I had an old bridge to try this on first!).

Thanks!
Dave

[Antonio Cotichini]

Is it ebony or rosewood? Anyway, if the bridge is natural wood (not varnish on it) you can fine sand just the broken area and use 0000 steel wool with a drop of lemon oil (or other oil good for wood) all over the bridge. Remember to mask and to put something absorbent under the pin holes area.

[Dave]

Antonio, The (cracked) bridge is ebony... as far as I can tell, it is unfiinished. But I can't tell if it has been treated with lemon or other oil in the past. The bridge plate inside is rosewood. I will see if I can shoot a couple pics and post them later this evening.

I looked to see what was available in the way of superglue at StewMac... their "thinnest" most flowing superglue (0010 #10 Thin) is quick setting (3-5 sec)... will this set to fast to penetrate into the crack?

Thx again for all the advice on this (relatively minor) repair.
Dave

[Dave]

Here's a picture of the bridge, showing the fine crack between the bass side pin holes. The bass pins were really in there tight. Most of the pins were 0.218-0.221" below the skirt, but two in the bass side were 0.224 and 0.228"... since I don't see any other structural issues, I really think the crack resulted from the pins being forced in.

[Antonio Cotichini]

O.K. My way: First, sand and save the wood dust just beside the crack. Second, fill a little of CA in the gap and spread the dust quickly. Repeat until the gap is closed. Sand with fine sand-paper. Then go with steel-wool and a drop of oil. It should work. I agree that the pins pressure may have caused the crack. Enlarge the holes if you want to use the original(?) pins or change them all with a new good sized set.
Let us know.

[Joshua Levin-Epstein]

Hi Dave,

Time for my 2 cents. It looks like the bridge has been sanded down in order to get better break over the saddle. The top of the bridge is pretty flat and the pin holes are not countersunk. This might not allow the bridge pins to seat all the way down, enticing the previous owner to introduce a bit of force. If the pins don't seat properly, the pin holes should be reamed and countersunk with the appropriate tools. The same would be true if you want to treat yourself to a new set of pins (like antonio suggests).

You can do the filling as everyone has described. I also wouldn't be surprised if the cracks reappear.

Joshua

[Dave]

Thx Antonio and Joshua. I will be getting a new set of bone pins sized for a better fit. For now, I took out the original plastic ones, and replaced them with a set of Tusq pins I keep around as temps (a little looser than I'd like, but OK for now). As far as I can tell, the bridge is at its original height. AFAIK, Guild didn't countersink their pin holes until some time after moving production to Tacoma. None of my old Westerly Guilds (I now have 7 from '71-'92 in five different woods) have countersunk holes. Thx everyone... I'll either try and do this myself, or chicken out and have my luthier/tech give it a go. Dave

[Antonio Cotichini]

Joshua is perfectly right. And if the crack will newly appear, take the bridge away and go with a new one. That instrument deserves it.