Google
 

Monday, April 16, 2007

Note to self.....

.... always make sure the go-bars are directly over the kerfing. Snap.... sproing.... yep, that is the sound I heard today. I was gluing the back to the sides, working my way around the go-bar deck when all the sudden two go-bars went flying across the shop and I heard that gut wrenching snap sound. I looked and found that I had put one of the go bars on the overhang at the lower bout and the pressure snapped a small section of the rosewood off at a grain line. Fortunately, the piece was mostly overhang material and the actual break was directly over the kerfing. I got it glued and clamped up. Hopefully the crack won't be too visible when I am finished. I figure that after I trim the overhang off, the actual broken piece will be approx. 1/4" wide and roughly 2" long. Heck, if this was the top the piece would just about be completely routed out for the binding and perfling channel. As it is now, the back binding channel will remove about half of the sliver so the actual glue seam will be fairly short and narrow. That alone should make it disappear.

Other than that little mishap, the glueup was pretty uneventful. It went easy and it sure was nice having the back literally sit on the sides like a lid. There was very little pressure to get a nice glue squeeze out. One thing I did notice is that my center seam is just a hair off center at the upper bout. I lined it up with the mold seam and because of the break I wasn't paying attention that the actual center of the block is just to the right of the seam. It is so close though that it won't be visible. It is probably 1 mm off center at the top and dead center on the bottom. Again, this wouldn't have happened had I not got interrupted trying to frantically repair the break before the glue set up. Oh well, one of these days I will get both the top and back plates perfect. Maybe on my next build!

After that was done I started shaving little bits of wood from the tone bars and top brace of the top and tapped along the way. I really didn't notice a difference in the tone so much as I did notice a difference in the resonance. After a bit of shaping and sanding I was able to get the top to make a ringing sound. I stopped there and hope it makes a positive difference in the completed instrument. I also glued a patch on the X brace intersection. I was going to glue a cap but after reading several posts from repairers they all recommend using a patch. They said they have seen a lot of cracked X braces that were capped or not reinforced but never with a patch. I figure if it has been good enough for Martin for all these years, it is good enough for me.

I picked up some strings for the OM and got it all completely stringed up and tuned. I have to say, it really sounds nice. I noticed a difference in the volume from yesterday to today. I guess that the string tension must have started pulling the top a bit and is starting to loosen it up. Of course it needs to be played to totally loosen up, but I was very surprised at the difference in tone just from one day of it being strung. My daughter played it a little and it really did sound nice.

On a sad side note, please take a minute and pray for the families of the VA Tech victims. This is a horrible story and they could use your prayers.





The back all glued up in the go-bar deck. If you look closely you can see the clamp I used to hold the broken piece in place while it dries.


A closeup of the break. The spring clamp on the right is butted against the side so you can see how much overhang I have. Too much overhang is not a good thing! This was my lesson for today.


The top all braced, sanded, patched, signed, and cleaned with naphtha. That is why it has wet looking spots. It is all ready for gluing to the sides. Well almost ready, I just realized looking at this picture that I forgot to drill the truss rod adjustment hole....... again. Sigh....


No comments: