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Recovering from a misplaced bridge

Posted: Tue Aug 08, 2017 6:44 am
by MaineGeezer
I am having more trouble with this guitar than I had with the other two guitars, three dulcimers, and cittern combined.

I got the body back from Carter. I spent an hour or two getting the neck aligned properly and glued in place. Then I located the bridge and glued that on. And I got it wrong. It's shifted aboiut 3/64" toward the bass side, as you can see by looking at the spaces from the 1st and 6th strings to the edges of the fingerboard in ths photo.
So I think I have a couple of options. One is to pull the bridge, patch the top and bridgeplate, and re-glue the bridge. Or I could cheat and pull the neck and cant it slightly so the strings are centered. Then I wouldn't have to patch the top or bridgeplate.

What would you do? Do I in fact need to patch the top and bridgeplate if I move the bridge 3/64" sideways?

Re: Guitar #3 -- an OM cutaway

Posted: Tue Aug 08, 2017 11:28 am
by Danl8
Do you have enough room on your bridge to shift the strings trebleside by plugging the bridgepin holes and re-drilling? I made a similar mistake on my cutaway by gluing 1/64" short causing intonation issues. Arghhh!

Re: Guitar #3 -- an OM cutaway

Posted: Tue Aug 08, 2017 4:32 pm
by MaineGeezer
That's an interesting possibility. If I had to move the holes straight forward or backward, I think it would work really well. Since I have to move the holes sideways though, I think the result wouldn't look symmetrical. It would save taking the bridge off though, which has a lot of appeal.

Re: Guitar #3 -- an OM cutaway

Posted: Tue Aug 08, 2017 4:45 pm
by MaineGeezer
Well, I dd take the bridge off. I've figured out where it should go. I drilled a 1/16" hole at either end of the saddle slot to use for a locating pin. The only thing left is plugging the holes in the guitar top and bridge plate. And then drilling new holes for the bridge pins. That last bit may be difficult. Because the old and new holes will overlap, there is going to be great incentive for the drill to wander because it will be drilling into dissimilar materials. Even if I make the plugs in two parts, the upper part of spruce to match the top and the lower part of maple to match the bridge plate, the glue joint may cause drill wander.

Maybe I can make a steel drilling jig, located by the holes I'm using locate the bridge. to guide the drill.

Maybe I'm over-thinking this whole process.

Re: Guitar #3 -- an OM cutaway

Posted: Thu Aug 10, 2017 6:51 pm
by ruby@magpage.com
I just use 2 waxed 3/16" drill bits in the outer two holes to keep the bridge in register. I think I even saw that one of the luthier suppliers has teflon dowels for this purpose.

Ed

Re: Guitar #3 -- an OM cutaway

Posted: Thu Aug 10, 2017 8:08 pm
by MaineGeezer
I dd that initially (locating pins in holes 1 and 6). Unfortunately, I still got it wrong....

After a marathon session today, I think I've finally got it under control. After measuring and checking six ways from Sunday I drilled the bridge pin holes in their new locations, and they look correct even after I've drilled them. I've got the repair of the top finish underway, fixing the damage I caused when I removed the bridge. So:

1. Finish the finish.
2. Glue on bridge.
3. Ream bridge pin holes.
4. String it up!
5. (I hope) verify that everything is correct.

Re: Guitar #3 -- an OM cutaway

Posted: Wed Aug 30, 2017 9:03 pm
by MaineGeezer
Update from the front:

I glued on the bridge. I put on strings. The up/down neck angle was wrong Even with the saddle cut down to almost nothing, the strings were still too high. Neck reset time, and it's not even finished yet!!!

Further inspection showed that the joint had failed -- the heel had lifted slightly. The neck was easy to get off, since it had aleady broken. Examination of the joint revealed that the glue had not failed. The butternut neck was so weak that the areas where the glue was had pulled off. This was due in part to only selective contact in the joint, so small areas had to take all the load.

I cleaned up the surfaces, took measures to ensure as complete surface contact as possible, checked angles, and glued the neck on again. This time the strings were, if anything, a bit too low, but not so much that the saddle needed to be impossibly high. Yahoo!

Then the truss rod broke.

That almost made me use impolite language.

SO! Today I took the neck off. Unlike the first time, this time is was well and truly GLUED. Nevertheless, I was able to get the neck loose with heat and steam with very little collateral damage. I was able to pull out tfhe broken truss rod without ermoving the fingerboard. Conceivably, I could slide in a new truss rod and use that neck...but I'm going to make a new neck. My karma with this one is toxic, or something.

On the positive side, the guitar sounds great.

Re: Guitar #3 -- an OM cutaway

Posted: Thu Aug 31, 2017 6:28 am
by Danl8
MaineGeezer wrote:...That almost made me use impolite language.....
LMAO. You're a better person than me; I was reduced to impolite language on my last gaff.

Progress on neck #2

Posted: Wed Sep 06, 2017 9:35 pm
by MaineGeezer
I've started to make a new neck out of cherry. The original has gotten to the point that it has too much bad karma for me to deal with it anymore, at least for now. I may put it on another guitar someday, but not this guitar.

So far, the new neck is progressing well. I was already hating the old neck at this point in its construction.

Re: Guitar #3 -- an OM cutaway

Posted: Sun Oct 22, 2017 6:55 am
by MaineGeezer
Things are proceeding. on the new neck. I sent the fingerboard to Diane for inlaying -- my eyes aren't up to it -- and she did a great j0b. I've trimmed it to width, glued it in place, bound the edges, installed the first 14 frets, and done a lot of shaping of the back of the neck:
I like this neck SO much more than the old one!