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Getting the ends of the soundpost to match the curvature of the top/bottom?

Discussion in 'Setup & Repair [DB]' started by lownotes02, Apr 12, 2005.


  1. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    Somebody gave me an old Mittenwald Bass (carved, I believe) with a soundpost that is rolling around in the bottom of the bass.
    Ive read on here the danger of not having it fit correctly. Since it looks like an old, carved bass (and has some cracks on the ribs and a couple of repaired cracks on top) I want to make sure its done right.
    I dont plan on doing the work myself, Im taking it to a luthier, but I wanted to ask him about his approach after I hear your opinions.

    How exactly do you get the ends of the soundpost to match the curvature of the top and bottom? Do you use the lipstick method the same way you would fit a bridge?
    Or do you make a template that fits the curve of the top and bottom, and then use that as a guide to round the edges accordingly so you dont have it sitting on an edge/corner?
    The post thats in there looks like it was cut with a radial arm saw. I put a square up to it, and it is square....but since the top is curved, Im afraid its been sitting on the beveled edges the whole time its been in the bass.
    Thanks in advance for your help.
     
  2. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    Fitting a soundpost is a bit like building a ship inside a bottle. Using a mirror through the ff holes, and visual access through the endpin hole, a soundpost is fit using the eyeball(s). Some folks will use chalk, but lots of bright light and patience are the main measuring tools. There are a variety of tools used in cutting the post, but what really matters is the end result: a fitted post without gaps.
     
  3. M_A_T_T

    M_A_T_T

    Mar 4, 2004
    Canada
    I don't know of any fancy jigs accept a lenght gauge, an "S" setter and a mirror & light. I'd say it's more like trial & error. Take off a shaving, fit post, take off another shaving, fit post... This is how I did it the two times I've fit soundposts in my bass, and the same for my other string instruments. I made a "retriever/pusher" from a coat hanger. One end has a "U" that can grab the post, the other has a "foot" to nudge the post from the bottom. I used the foot along with the "clover" looking end of the violin "S" tool to get the post into place. I used this cool light/mirror tool I made to look inside, and when I saw a gap, I'd note it's location, remove the post with the retriever and shave down the area slightly, and repeat. Took me like 5hours to do the original post. I got an exellent fit, but it was this garbage piece of chipped Pine, so I ended up turning a few new ones on my lathe from Sitka Spruce, and spent another 5hours fitting the new one (actually blowing one and starting over). I am very pleased with the current post. It has a perfect gap-less fit, plus I got it fit in the exact spot I was shooting for, which I've never done before. I'd say my light/mirror tool was the biggest help.
     
  4. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    Thx Nick and Matt. I can borrow an inspection mirror from my buddy who got a kit from Lemur that has that and a rubber coated, S-shaped hook. I also have a string of small, white-bulbed Xmas lites that should light up the inside, if not Ill buy one similar to the pic that Will posted.
    I recently moved so I'm no longer near my old Luthier in Fl, and I wanted to be able to ck out this other guy's work after he resets my soundpost. It sounds like you have the "5 min wonders" who just throw it in there, beveled edges and all, vs. guys like yourself who take the time to do it right.
    Thanks for the advice.
     
  5. I've only set one sound post;- I used an itty-bitty book light (usually it is on the music stand) slipped in the f-hole and that was plenty of light. I use two mirrors taped to baling wire , one is the 2 in. circular wide angle variety you can get at the supermarket auto section and the other is a thin piece cut from a cheap broken mirror with taped edges. I also improvised a setting tool from wire, much stiffer than a coat hanger though. It worked in a pinch but it was totally trial and error for the fitting. Just so I didn't get the ends mixed up, I put a green highlighter stripe down the grain at the top so I was always able to know which end to work on.
     
  6. M_A_T_T

    M_A_T_T

    Mar 4, 2004
    Canada
    I stabbed the soundpost setter 2/3 the way to the front facing side, so I always know the hole is closest to the top.
     
  7. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    Good points. Having the front/back and top/bottom marked helps when you get it out of there for trimming.

    I saw a Kay Bass, I think the model was an M-1 or C-1. The owner said he looked it up on a website that dates Kays and it looks like it was made in the 60's. There was a circular wafer in between the bottom plate and the bottom end of the soundpost. It was the same color as the inside of the back and the soundpost, as if it was that way from the factory.

    Is this a common thing on this model Kay? Other basses Ive seen have the post in direct contact with the plate. I dont know if Kay did this to help support a thinner top/back or if a repairman put that in there to camouflage an ill-fitting soundpost.

    Would having that disc in there affect the top/bottom vibration and the sound?
     
  8. ctxbass

    ctxbass Supporting Member

    Nov 6, 2003
    Central Texas
    The reinforcement disc is standard on Kay basses from that era.
     
  9. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA
    My Shen has a post patch on the back. If it is fitted correctly and glued up right, it shouldn't create a problem. It just reinforces the laminate back.

    A side benefit of the patch is that it can be fitted so it matches the contour of the back and is flat on the post side, so the post can be simply cut square. That way, you need match only the top to the post.
     
  10. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    It seems like that would be a good idea considering you have all that pressure on the plates sitting on a post with the circumference of a dime. I wonder why other basses dont have this. Maybe it acts like some kind of insulator/buffer.

    Chasarm, did your Shen sound any different after you had it repaired?
     
  11. luthierbass

    luthierbass

    Jan 2, 2005
    i work in a music store in long beach.. we deal with tons of basses.. first we fit the soundpost to the top with the soundpost outside of the bass. If you have a bass that has been made right the curves of the top should match the inside. Once one side fits you find out how long it has to be and fit the other side of the soundpost to the top as well. Both the top and back angles wont be the same but its not far off. Once thats done you will have a soundpost that will be in the ballpark fit. put it in and check it with an inspection mirror. thats about it..
     
  12. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Bettendorf, IA USA
    It wasn't repaired. The patch was put in during the build.
     
  13. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    My bad. I just associated the word "patch" with a repair job.
    Ive read lots of good reviews on the Shen, and Kays are known for their durability. Theyve obviously reinforced a vulnerable area.
     
  14. Jeff Bollbach

    Jeff Bollbach Jeff Bollbach Luthier, Inc.

    Dec 12, 2001
    freeport, ny
    Yup, that's all you gotta do!
     
  15. nicklloyd

    nicklloyd Supporting Member/Luthier

    Jan 27, 2002
    Cincinnati, Ohio
    It's as easy as setting a neck: make a hole, glue it in.
     
  16. luthierbass, I don't understand??? What do you mean by "fit the post to the top with the soundpost outside the bass?????? The outside curve is covex and the post needs to be convex also. Are you saying you are eyeballing the curve needed by looking at the top curve????? How can one side fit before you try it in place????

    If you are going to post as an expert, you may need to spend a little more time on accuracy and a thorough description.
     
  17. M_A_T_T

    M_A_T_T

    Mar 4, 2004
    Canada
  18. erik II

    erik II

    Jul 11, 2000
    Oslo, Norway
    Here's an idea for a curvature adaptive, length adjustable soundpost:

    [​IMG]

    How would this voik...? :D
     
  19. How can you say this is curve adaptive? Those concave base pieces still must fit the interior curvature of the top and bottom plates perfectly, just as the top and bottom of a one-piece post would have to.

    As for length, I would wonder effect the change in diameter might have on vibration transmission.
     
  20. lownotes02

    lownotes02

    Jan 19, 2005
    Melbourne, Fl
    Nice pics, Matt. I appreciate everybody's input.
    While I wont tackle this on my Mittenwald, I have a chinese junk that my old luthier refused to work on anymore (cant say I blame him) so I'll experiment on that one since its basically firewood.
    Can somebody tell me what the advantage is of using cleats (I think thats the right term) vs a solid piece of wood to repair a crack? I think I saw some pics of a crack repair on here where small, seperate pieces of wood were used instead of a solid one that runs the length of the crack.
    Thanks in advance for your help.