Official Luthiers Forum!
http://www.luthiersforum.com/forum/

Split Bridge at Saddle Slot -- Update
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=34338		 Page 1 of 1
Author:  George L [ Wed Nov 23, 2011 11:40 am ]
Post subject:  Split Bridge at Saddle Slot -- Update
Dang! I'm loving my most recently completed guitar and have been playing the heck out of it ever since stringing it up. Well, last night I started hearing odd intonation issues. Looking things over I noticed a pronounced forward lean in the saddle. Yikes! Closer inspection revealed a split in the bridge that runs along the front edge of the saddle slot and down toward the top. It has started to work out toward the wings of the bridge as well. The bridge can be replaced, of course, but this is an opportunity for me to diagnose what went wrong and maybe learn more about this type of repair.

Here are the specs:

Bridge material: East Indian Rosewood
Height of bridge at center: .36"
Minimum width of material in front of (angled) saddle slot: .19"
Saddle slot depth: .16"
Amount of saddle exposed: .16"
String height above top: .52"

These numbers seemed okay to me, but I'm a rookie. The saddle was pretty snug in the slot. Not so tight that you needed channel locks to pull it out, but not flopping around either. Am I missing something here? Or did I just get unlucky with this particular piece of rosewood?

Assuming there is no fundamental flaw in my specs above, might I consider a glue repair? It's a fresh, clean crack, so I thought this might be worth a shot. Think it would work? If so, is HHG the right glue for the job? CA? Or maybe this a bad idea all the way around? Advice and opinions would be greatly appreciated.

Thanks,
Author:  Tom West [ Wed Nov 23, 2011 12:14 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
George: These numbers seem OK to me. I might make the slot a bit deeper but don't think that was your problem. You may have been a victim of a pre-existing check or crack. A good precaution is to wipe the blank with something like acetone to show up any defects. If it was my repair I'd remove and replace. Peace of mind.
Tom
Author:  George L [ Wed Nov 23, 2011 5:02 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
Thanks, Tom. I appreciate your reply!
Author:  George L [ Wed Nov 23, 2011 6:48 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
Thanks, Todd! Both you and Tom are helping me a lot. I'll crack open a Dogfish Head Punkin Ale in your honor later on this evening.
Author:  Bobc [ Wed Nov 23, 2011 7:22 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
Thin cyano works quite well for a repair like this. If you use cyano protect the top with masking tape.
Author:  George L [ Wed Nov 23, 2011 8:29 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
Indeed, before removing and replacing the bridge I thought I would take this chance to experiment with glue. I mixed up a small batch of slightly thin HHG, filled a syringe with it, flexed the crack open and squirted glue down into and all along the crack. It appears to have wicked in fairly well. I'll let it sit overnight and we'll see what the morning brings. I do have a back up bridge with a deeper slot standing by.

Thanks again for all the replies.

Cheers,
Author:  nickton [ Thu Nov 24, 2011 12:16 am ]
Post subject:  Re: Split Bridge at Saddle Slot
That repaired crack might be even stronger than the original. You could also probably glue a small strip of rosewood on the front end as re enforcement. It would be hardly noticeable if carefully done, and you wouldn't have to build a new bridge and re set it again.
Author:  George L [ Fri Nov 25, 2011 12:19 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
My efforts at gluing the crack didn't work, so I'll be tackling a bridge replacement procedure later on today. I replaced the bridge on another guitar once before and it turned out okay. Hopefully this time it will go even better.
Author:  murrmac [ Fri Nov 25, 2011 5:03 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
George L wrote:
My efforts at gluing the crack didn't work,


Did you use any kind of clamping system after wicking the HHG in ?
Author:  George L [ Fri Nov 25, 2011 5:33 pm ]
Post subject:  Re: Split Bridge at Saddle Slot
Well, I managed to get the bridge off without destroying the top of the guitar. Woo hoo! The bad news is that I did mess up one section of the spruce beneath the bridge. I could feel this as it was happening, so I backed my putty knife out and finished up from the other direction. There are no big chunks missing, but a few wood fibers are loose along one edge. I'm not sure how to go about preparing this surface for affixing a new bridge. Since hide glue sticks to hide glue, can I just glue these edges down and proceed normally? All advice and insight will be welcomed.

(Sorry, Murrmac, I didn't see your reply above until just now. Yes, I used a small caul to add clamping pressure to the glued crack. I think I didn't get as much glue wicking into the crack as I had hoped. When I stressed the glued area the top edge was tight but the wood still flexed, so it seemed to be a pretty superficial repair.)

Thanks,
George

P.S. Here's a (lousy) pic of what's going on...

Image
Author:  woody b [ Sat Nov 26, 2011 8:25 am ]
Post subject:  Re: Split Bridge at Saddle Slot -- Update
I suspect you were a victim of a hidden flaw in your bridge blank. Like Todd I leave 1/16" or so of wood below the slot, so my slot's deeper than yours. My reasoning for this depth is twofold. Bone (or whatever the bridge material is) is denser, and lower damping than wood. Also, if someone ever wants to install a UST they won't have to deepen the slot. I also route my slot at a 7 degree back angle....saddle leaning toward the pins. I believe this could make the slot stronger. It also helps keep the intonation consistant if the action is lowered, or raised. This angle has to be taken into account when locating the slot.
Author:  Ken Jones [ Sat Nov 26, 2011 9:35 pm ]
Post subject:  Re: Split Bridge at Saddle Slot -- Update
Sounds like the bridge was too well quartered to begin with. I'd replace it. I like a decent amount of rift for that reason.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/