Cracked bridge on my Eastman

[charles Tauber]

Originally Posted by phavriluk

I've made bridges and I'd love to be educated in avoiding repairs I could have avoided.

To avoid failures, it is helpful to understand the cause of the failures. There are a number of fairly common failures in bridge design and implementation. Here are a few:

1. The saddle slot fails/splits at the front face of the saddle. This can be avoided by ensuring there is enough wood in front of the saddle to handle the load. A forward-leaning saddle - usually caused by a too-loose saddle for the slot - places additional load on the front of the saddle slot. An overly tall saddle increases the torque (load) on the front of the saddle slot. To avoid those failures, ensure 3/16" or more of wood in front of the saddle; ensure that the saddle doesn't project excessively from the top of the bridge - a guideline is not more than 3/16" or so; and, ensure that the saddle fits appropriately that it does not lean forward under string pressure.

Other causes of the saddle slot failing are the saddle slot being too shallow: a rule of thumb is to have at least as much saddle embedded in the slot as projects from the top of the bridge. Through saddle slots are weaker than "blind" saddle slots: manufacturers who use through saddle slots often glue the saddles into the slot to increase the strength of the slot.

2. Another common bridge failure is splitting of the bridge through the pin holes - in a pin bridge. That can be due to an "unfortunate" grain orientation, or it can be caused by ill-fitting bridge pins, or pressing the pins into the holes too tightly. One approach that some use is to make sure that the bridge pins/holes are not on the same line, distributing the forces so they don't all lie on the same line. It should go without saying that if one uses tapered pins, the holes should also be tapered to match. (An age-old method of splitting rock is to place a pair of "feathers" (wedges) in a cylindrical hole drilled in the rock, then hit the feathers with a hammer to split the rock.)

If the holes are properly tapered and sized for the pins, the collar on the pins will bottom out, preventing the pins from splitting the bridge.

3. Some manufacturers bolt and glue their bridges, often hiding the bolt heads under a "decorative" dot. It isn't uncommon to have splits in the top along a grain line that runs through the bolt holes. While the bolts will prevent the bridge from "flying off" in the event of glue failure, the bridge pins will also. Some might use the bolts for alignment purposes when gluing the bridge: there are other effective ways to accomplish that without using bolts. In some cases where the glue fails, the bridge splits though the bolts. One way to avoid those failures is to not use bolts as a permanent component of the bridge attachement.

4. Excessive wear of bridge plates can occur related to the geometry of the pins and pin holes. The best way to eliminate excessive wear of the bridge plate is to use un-slotted pins in slotted holes. Doing so forces the ball on the end of the string to be displaced from the hole, preventing the premature wear at the edges of the holes in the bridge plate.

5. While not necessarily a bridge failure, itself, it is common that the glue joint between bridge and guitar top fail. Failure is generally due to a peeling action from the rear (butt side) of the bridge. A too narrow bridge will increase the peeling stresses, as can a too flexible top in the area surrounding the bridge. The area can be made less flexible through some combinations of a thicker top, appropriate size and placement of braces and appropriate material, thickness, size and placement of a bridge plate.

Those are the most common bridge-related failures that come to my mind. I'm sure there are others that I haven't thought of.

[KenL]

Picked up the Eastman this morning and am pretty amazed at the work done by Jeff at the Rocky Mountain Guitar Co. If you didn't know that it had a cracked bridge, you would never spot the repair. It looks great!

Jeff said that there is a chance that the glue will not hold, but he also knows that I have a new OEM bridge for it. So if it cracks again, we'll deal with it.

Anyway, I'm very happy to have this sweet little guitar back home and looking good again!

20210402_132328.jpg20210402_132247.jpg

Thanks to all for your opinions and tips. Very helpful.

[Mr. Paul]

Nice when a guitar can be brought back to good health by a "pill" rather than major surgery

Jeff has done very fine work for me on 3 different guitars, we're fortunate to have such a fine craftsman in our region.

[KenL]

Yes we are, Mr. Paul. Plus he's a knowledgeable guy and is willing to share what he knows. I learn something new every time I go in there.

[KenL]

I'm reviving this thread just to say that I sold this guitar not too long after I had the bridge repaired. Sold it to a lady down in Denver who sent me a note about a week later telling me that she was delighted with the little thing.

But then I just now spotted it (via the internet, not in person) hanging on the wall, for sale, at the Olde Town Pickin' Parlor in Arvada. Easy for me to spot thanks to the custom Holter pickguard.

If anyone is looking for a really nice Eastman parlor, here you go:

https://www.picknparlor.com/acoustic...s/eastman-e20p

[FingahPickah]

Ken - (One Guild as well as Eastman guy to another)

I hope it works out for you. But "....there is a chance that the glue will not hold, but he also knows that I have a new OEM bridge for it. So if it cracks again, we'll deal with it."

Bridge removal and replacement is actually a pretty common repair and not a big deal in the hands of a experienced/reputable repair tech.

I had the same thing 25+ yrs ago on my '73 Guild D44M. At the time, the Westerly, R.I. factory was still in operation. I brought it to them.

The technician said - a replacement bridge (with a slightly oversized footprint) was the only real solution. (Granted it was the factory).

I gave the "go" and have never had an issue since.

[hubcapsc]

That can be due to an "unfortunate" grain orientation

I was looking at j-35 bridges on the internet, and on my j-35, and
noticed many "rift sawn" bridges... I guess that was on purpose
and is a "fortunate" grain orientation?

-Mike

[KenL]

FP- many years ago, in the early days of eBay, I spotted a Guild bridge for sale and ended up buying it for cheap. Bought it just to have it.

It is rosewood, not ebony, but still a very nice piece of wood. Might even be Brazilian.

Doubt I'll ever need it. If you do, let me know and I'll make you (or any other AGFer) a deal.

I have learned since that not all Guild bridges are of the exact same dimensions. So I don't know if it would fit either of mine anyway.


Note: I made myself curious, and since I knew exactly where the bridge was (because I ran across it the other day and said "Oh, jeez, I still have that?"), I got it out and lined it up with the bridge on my D-46. It appears to have the same outline, but the string spacing is narrower.

Pretty sure it is Brazilian, though.

[sharkblues]

Originally Posted by KenL

UPDATE:

I found an email address on the Eastman Guitars website. Sent them an email telling them about the badly cracked bridge and asked if I could buy a new one.

When I didn't hear back from them, I took the guitar to Rocky Mountain Guitars in Salida. This is Jeff Bamburg's shop; he builds outstanding custom guitars. He had a look at it and recommended that we try gluing it first, and that the chances of it working were 50/50. If it didn't work, he would replace the bridge.

So I left it with him, and headed home. Found an email from my inbox from Eastman, and they are sending me a new bridge. I kinda thought they might.

Called Jeff, and he recommended that we stick to the original plan of gluing it first. Okay, good, hope it works. If not, I'll have a OEM replacement bridge in hand.

PS, he really liked the Eastman. Here's a guy that build $6k-$10K custom guitars, and he was admiring my inexpensive little MIC guitar!

Good on Eastman!