Official Luthiers Forum! :: View topic - Bridge rotation solution

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

Bridge rotation solution http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=39138	Page 1 of 1

Author:	tjp [ Tue Jan 29, 2013 12:56 am ]
Post subject:	Bridge rotation solution
Finished up #2.5 (retopped #2), and she sounds wonderful. Went a little thin on the top, however, so there is more bridge rotation than I'd like. It's split between sagging in front of the bridge and bulging behind it. It goes away probably 60%, to an entirely acceptable level if I tune down a step. Yes I could tune it down. Yes, I could use ultra light strings. But I'm learning, so I want to do things the hard way. Parlor size. My instinct is to put a 1-1.5 in spruce bridge plate in front of the existing bridge plate. You think that'd work? Any other ideas? Bracing here:

Author:	Tom West [ Tue Jan 29, 2013 8:54 am ]
Post subject:	Re: Bridge rotation solution
The strongest part of your X brace is located very close to the bridge ends and the bridge is tending to roll into the weakest part(scallops).This approach is different then most where the bridge is located near the weak area(scallops) and tends to roll into the stronger part of the X(where they cross).As Todd has said support behind bridge may help in general and support in front may help the roll.Pulling the X back further may be a help for future guitars of this size. Tom

Author:	tjp [ Tue Jan 29, 2013 9:02 am ]
Post subject:	Re: Bridge rotation solution
Thanks Todd. It's a parlor, sinker rw that washed up on my friend's land a few years ago. I still need to go rifle through the barn and find some more QS stuff. Very pretty wood, but on this piece the lighter wood in the middle is pretty soft and floppy. The mineral stained wood is very stiff and much denser. Had to be careful when thicknessing to take the different densities into account. It's about .120 thick. Bridge is 1" by 7", just catches the braces with the front corner. The belly is visible from the side after a day, I was concerned that over time I would have a real problem. I suppose one strategy is to just string it up, play it, and see what happens. Sure sounds nice! Tom, I was concerned about that too. I just stuck with the Antes layout for lack of a better idea... Bonehead move: When gluing the bridge, I placed a block of redwood under the clamps to support their weight. Well, the block had a dollop of dried glue on it, so when I pulled it out it put a big ol' gouge in the top. I suppose I should leave it there as a reminder of my stupidity. Tom

Author:	Darryl Young [ Tue Jan 29, 2013 9:12 am ]
Post subject:	Re: Bridge rotation solution
Maybe measure the angle of th ebridge before stringing up. Then string up and play for a day or two and then measure the bridge angle again. Then you will know how much it rotated (3deg, 7deg, etc.) and you can post back on this thread and folks would have an idea if this is enough bridge rotation to cause concern. Best I recall Gore states in his book that 3-5 deg of brdge rotation is ok.

Author:	Goodin [ Tue Jan 29, 2013 9:43 am ]
Post subject:	Re: Bridge rotation solution
You can always just put on lighter gauge strings. D'Addario makes light and ultra light sets.

Author:	Alan Carruth [ Tue Jan 29, 2013 4:07 pm ]
Post subject:	Re: Bridge rotation solution
Reducing the leverage on the saddle would help if you can do that. Getting the strings a little closer to the top surface should be enough, since tuning down suffices. I'd just make ther top thicker next time, though...

Author:	tjp [ Tue Jan 29, 2013 6:57 pm ]
Post subject:	Re: Bridge rotation solution
"I'd just make ther top thicker next time, though..." Oh Alan, you really know how to hit a guy where it hurts, don't you? The best part is that I did it twice in a row. I appreciate all the responses. I don't think I'm at 5%, at least in the short-term, and I will reduce leverage a bit as I refine the action. I'm going to play the heck out of it and wait for it to settle in, while trying not to look at the big dent in the side of a beautiful sinker guitar. Once it settles in, I'll decide on a course of action. Who knows? In the meantime, will be starting a set of fraternal 000 twins for two of my buddies. Walnut from the same billet, essentially identical save for binding and the fact that one will be Adi, one Sitka. Looking forward to it. The tops will NOT be ovely thin, thankyouverymuch. .11 ish....good, stiff, uniform stuff this time.

Author:	mhammond [ Tue Jan 29, 2013 11:57 pm ]
Post subject:	Re: Bridge rotation solution
Tom: A little judiciously applied steam will probably remove the dent. Try it you'll like it... Mikey

Page 1 of 1	All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/