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Thread: Small rattle in soundboard...

  1. #1

    Default Small rattle in soundboard...

    I decided to throw together a mandolin using only pieces of wood I have lying around the place. I'm more concerned at this stage about learning the techniques involved in building instruments then the sound of the finished one. So far so good, but yesterday I glued the bracing to my, cue shock and horror, red deal soundboard! With, wait for it, red deal bracing

    When I released the clamps this morning and gave it a tap I noticed a slight rattle at different parts of the board. The bracing seems to be tight all around the board, especially at the ends. There are the tiniest little gaps at places along the bracing, but I can't get say a sheet of paper under them, or through them.

    I also wonder if it could be because I didn't take enough care in joining the two halves of the sound board together? I guess I can't ignore it could just be the result of using such poor wood in the first place.

    Worst case scenario, I can simply remove the bracing and try again. I can also just cut up some new wood and try the whole thing again. I guess that's the nice thing about using scrap!

  2. #2
    Registered User sunburst's Avatar
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    Default Re: Small rattle in soundboard...

    When you tap and hear a rattle, it could be anywhere.
    I'm not absolutely clear on your stage of completion, but check everything, tap everywhere, listen from every direction, you might track it down. Also, grab and hold parts while you tap and see if you can damp the rattle. If you can, you might have found it.

  3. #3

    Default Re: Small rattle in soundboard...

    I remember being mystified (before Google) when reading Brit literature, like Dickens, where something called deal was disparaged about the same way we speak of particleboard. If you have scotch pine, pinus sylvestris, there probably isn’t much US experience with it, other than Christmas trees! I’d guess that it has the general characteristics for a tonewood, except maybe only being smaller trees with not great choice of sawn orientation. Not my field! But rattles can come from anywhere, so localizing them could be tricky since the whole structure can participate. Maybe putting a few clamps back on would help find the culprit by elimination.

  4. #4
    Registered User John Kelly's Avatar
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    Default Re: Small rattle in soundboard...

    Rory, I think your opening sentence says a great deal about why you might be experiencing problems with rattles. You say that you "decided to throw together a mandolin using only pieces of wood I have lying around the place". You mention perhaps not having accurately jointed the two halves of the soundboard, and there being slight gaps under parts of the bracing. If this is how you approached the process, then you have maybe built in problems right from the start. This is not meant as a criticism of you but just a general observation from what you say.

    When I attended the excellent Stringed Instruments Course at Anniesland College in Glasgow here in Scotland in 2004 after retiring from my career in teaching one of the strongest points the tutors kept reinforcing was the need for really high accuracy in preparing all the pieces we were going to be using. I remember standing at a big window in he workshop and placing the two halves of my planed soundboard together against the window glass and looking closely for the tiniest gaps between the boards. If we found any, it was back to the hand plane again (apart from the bandsaw we worked almost exclusively with hand tools). This rigid adherence to a level of very high accuracy certainly paid off and I have since built round 40 instruments, and those I have had problems with have generally been down to my trying to cut the odd corners and getting a bit slipshod in my preparation. As John H has said, the rattle can be anywhere. Finding it will be a great learning experience and I would ot worry too much about the fact that your timber was not of a recognised quality. The last two or three instruments I have made have necks made from an old Victorian era wardrobe I go from someone who was going to break it up for firewood. It was over 100 years old and the mahogany I got from it was very stable.
    Enjoy your building journey. I am still enjoing mine!
    I'm playing all the right notes, but not necessarily in the right order. - Eric Morecambe

    http://www.youtube.com/user/TheOldBores

  5. #5

    Default Re: Small rattle in soundboard...

    I commend you on your journey building with scrap. There is so much to learn. So after you have mastered your skills and are ready for your best deal you can belly up to the table with a clean plate.

  6. #6

    Default Re: Small rattle in soundboard...

    Thanks for the all the replies. After going through the suggestions, I found that a long G-Clamp fixed to one particular position along one of the braces stops the rattle. Great. Now should I just try to apply glue under it, or take the entire brace off first and then re-glue? Time for some reading I think!

    To John: you are absolutely correct to remind me that high levels of accuracy are an absolute must, throughout the entire process of the build. I am doing what I can with my current woodworking skills. Experience will teach me a great deal.

    Btw, this was my first post to this forum after reading so so many posts. Let me say thanks to the super community here. I've already learned so much from you all

  7. #7

    Default Re: Small rattle in soundboard...

    You should take it apart, prep the joint to perfection then reglue. You do not say what kind of glue you are using but if it is anything other than hot hide glue then trying to drive more glue in over the top of the old glue is fruitless. New glue will not stick to old except with hot hide glue. If it is carpenters glue or Epoxy or anything like that the joint on both halves must be completely cleaned down into the surface to remove any traces of old glue that has penetrated.

    If your center join is less than perfect or you have any suspicion of it you might wish to consider taking it apart and redoing it. It is under very high stress due to string pressure on the bridge and will separate over time if there are any flaws. It has as much stress as any joint on the instrument except possibly the neck to body joint.

    Recommended glues are hot hide glue if you are somewhat experienced with woodworking or original Titebond. Other carpenter glues, including later Titebond formulas, will creep over time and epoxy is brittle. Joint preparation is everything regardless of the type of glue you are using.

    Also look closely for cracks, pitch pockets or other flaws in the wood itself which may be the culprit in your buzz.

  8. #8

    Default Re: Small rattle in soundboard...

    Thanks CarlM. I'll probably just cut new pieces and start the soundboard again. I have plenty of that old pine here. Guilty as charged on the glue though. It's just a standard carpenter's wood glue.

  9. #9
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    Default Re: Small rattle in soundboard...

    Quote Originally Posted by RoryWalsh View Post
    Thanks CarlM. I'll probably just cut new pieces and start the soundboard again. I have plenty of that old pine here. Guilty as charged on the glue though. It's just a standard carpenter's wood glue.
    You could always saw the joint apart, plane, and glue it up again. It would be easy to simply saw it apart.
    THE WORLD IS A BETTER PLACE JUST FOR YOUR SMILE!

  10. #10

    Default Re: Small rattle in soundboard...

    Wow, I always wondered what a "deal table" was. I assumed it was a kind of farm table, but it really means "pine table"? Huh. Makes sense. I'm writing this from a 200-year-old deal table right now...

  11. #11

    Default Re: Small rattle in soundboard...

    Quote Originally Posted by Marty Jacobson View Post
    Wow, I always wondered what a "deal table" was. I assumed it was a kind of farm table, but it really means "pine table"? Huh. Makes sense. I'm writing this from a 200-year-old deal table right now...
    As Charlie Poole said "Don't let your deal go down"

  12. #12

    Default Re: Small rattle in soundboard...

    Quote Originally Posted by pops1 View Post
    You could always saw the joint apart, plane, and glue it up again. It would be easy to simply saw it apart.
    Only my max resaw size just about gets me a soundboard that matches that of the Phil Davidson mandolin that I'm measuring up from. So if I saw the joint apart my halves will probably be a little narrow.

    Being to able to grab another piece of wood and learn by making mistakes is a lot of fun. I've built things before where I have had to get it right the first time, or risk ruining some really nice timber. But going down the salvaged wood route is a lot of fun. Btw, when I say I'm trying to copy the scale of that Davidson mandolin, it's really only the body. I just happen to have a few finished tenor Ukulele fingerboards. So I'm going to use one of those with it. I guess that makes this build an octave mandolin, with a regular mandolin body

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