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Glassbedding

Discussion in 'Hardware, Setup & Repair [BG]' started by slick77, Jan 4, 2001.


  1. slick77

    slick77

    Nov 22, 2000
    Has anyone tried glassbedding a bolt on neck,like gunsmiths do to rifles?Any reason why it wouldn't work?
     
  2. do you mean to clean the paint off?
    i think it would wear away at the wood and probaly cause a lot of pitting.
     
  3. slick77

    slick77

    Nov 22, 2000
    What I mean is the process of removing wood from the neck pocket and replacing it with fiberglass resin.The neck is coated with a release agent and bolted into the wet resin,at the optimal position.When the glass hardens,you should have a "perfectly" fitted neck.Shooters use this method to increase the accuracy of rifles.I think it might work with basses and guitars.
     
  4. oh sorry man you said glass bedding, i thought you said glass beading wich is like sand blasting
    whoops
     
  5. rllefebv

    rllefebv

    Oct 17, 2000
    Newberg, Oregon
    Sounds interesting. I'm wondering what the acoustic properties of the fibreglass resin are. Does it transmit vibration well, etc. Could be that while you are getting a solid, well formed neck joint, you may well be sacrificing acoustic coupling. I'm sure that the barrel and firing mechanisim of a gun fit more solidly using this method, but then again, a gun doesn't have to sound good.

    If you try this method, please let us know how it goes.

    -robert
     
  6. slick77

    slick77

    Nov 22, 2000
    Yeah,the acoustic properties are one concern.The other thing I wonder about is how well the glass will stand up to the vibrations.when laying up a body you can't use epoxy because its to hard.The vibrations will shatter the epoxy.Could the same thing happen in the neck pocket?I really want to try this,but I'm kind of chicken.
     
  7. I proposed exactly the same thing a year ago to the forum! My dad was a gunsmith and the idea just sprung naturally from that. I thought it could be used in extreme cases, on used instruments as more of a repair. The idea drew a little interest but the thread also uncovered the flaw IMO. With this method of setting a neck, you would run the risk of creating a joint that would split should the neck expand at a different rate than the body. It would be just that tight! In a rifle, the barrel and action don't expand and contract much at all like wood. And, after building my own bass recently, I've come to the conclusion that a good stable neck joint can be achieved with tight screws alone. After all of that, the additional work didn't seem like a great idea anymore:)

    Hey rllefebv - a rifle may not have to sound good but the shock waves experienced by the resin in a bedded stock are probably hundreds of times more powerful than that of a musical instrument. There isn't much doubt that the resin can take the severe punishment and do quite nicely.
     
  8. slick77

    slick77

    Nov 22, 2000
    Hmmm,A good point.But,shouldn't a hard maple neck,being very dense,expand less than a body built of a less dense wood like ash or poplar?
     
  9. rllefebv

    rllefebv

    Oct 17, 2000
    Newberg, Oregon
    Absolutely Hambone. There was absolutely no doubt in my mind that the glass could take a drubbing. I was doubting it's ability to efficiently transmit the vibration from the neck to the body, to sing as it were...

    Actually, for refitting a neck to a badly formed pocket, I've had luck by re-routing the pocket somewhat larger and inlaying a new block of wood of the same type used for either the body or the neck. I use hide glue for the join, then route out a new pocket. Takes some care, but the result was more than satisfactory...

    -robert
     
  10. Yeah, a maple neck won't do too much growing but the body can shrink if dry or the neck could cantilever and split something.

    I always thought that the resin would be a good thing for transmitting vibrations to the body. I assumed that since Ovation guitars were fiberglass that it wouldn't be a problem.

    I like your approach to a pocket that is out of limits. If done with care it could be unnoticable, even on a natural finish :cool:
     
  11. slick77

    slick77

    Nov 22, 2000
    I was thinking of using this technique to assemble extremely accurately new guitars.After getting this input I think what I'll do is look for a cheap guitar from a pawnshop to experiment on.My next question is how to determine the tonal effect on a cheap instument,sound being so subjective?
     
  12. If getting the tightest connection between the neck and the body is the goal, then you really don't need to bed the neck as described. I just built a bass and instead of the usual wood screws, used steel inserts in the neck and stainless steel machine screws through the body. The results were a very, very tight neck joint and the ability to remove it without degradation of the screw holes over time. I really recommend it.
     
  13. slick77

    slick77

    Nov 22, 2000
    Thanks Hambone!I've heard of that method and need to do it to my main bass.Where can I get the parts?
     
  14. The parts aren't uncommon but it'll take a good hardware store to carry them. I'm blessed with one of the best here locally and they never fail to come up with whatever I need for some of my hairbrained ideas :rolleyes: You might find them under the name of "furniture connectors" (thanx pkr2).
    They will come in 2 different types: hex head and slotted. I think the hex heads are better cuz they are easily twisted into the neck with even pressure. You can chuck an allen wrench into a drill press to do this. I used a set of 1/4-20's but you could use the next smaller size (10-20 I think). As a lubricant and filler, I spread white glue around the insert as I threaded it into the neck. This was to fill any voids and keep the insert from backing out.

    There is something else that you can do. When I was building the CAD/CAM bass, I started with the neck as the primary building block around which I centered all of the other components. I took the neck and placed it flat on a piece of paper while I traced the contour of the heel. Next, I drew a centerline down the middle and scanned the contour into the computer. Of course I had to do this to create the router files, but I also used the computer to make an inline on my tracing to compensate for the offset of the pen used for the tracing. The result of my first blank test was a pocket that was too tight!. I added about .004" to the contour and voila! a really tight pocket. I would recommend doing this when you make your pocket template. You can cut the contour out of cardstock and fine tune your pocket to get just what you want in fit.

    [Edited by Hambone on 01-10-2001 at 05:53 PM]