Nice revival of an old thread. I add the belly patch to old Kays all of the time.It makes a big structural and tonal difference with them. Once you get the shape of the arch back where you want it, then I add the patch, usually in two layers of approx. .075" each. Layering it is a lot easier than trying to get a big thick section of spruce to conform. In my market this has no detrimental effect on the resale price; if anything it puts the bass in a slightly better advantage to one that has a sinking top and my experience has been, all other thing being equal, a bass sounds a little better with a correctly done belly patch.' Maybe a little bit more focus and punch; it is still the sound of an old Kay, but a better one.
This is one of the areas where I always use red or Adirondack spruce. Some folks will chime in with different opinions (around here...imagine that!!!), but my experience is that high grades of red spruce tend to be a lot stronger and stiffer than the others, and it deforms a lot less than the other spruces, to the point that it takes a bit of a learning curve to get used to it.
I work on a LOT of prewar and 19th century Martin guitars that were made with red spruce and they tend to be night vs. day different compared to anything after 1946 when they switched to sitka, so they are a very good reference in terms of what works well over the test of time. The older pre-war red spruce models tend to be about 1/3 less mass and yet they have virtually none of the deformation issues, especially behind the bridge, that the sitka models do. I'm sure the local thought police that spend all of their time on the computer and never working on instruments will likely jump all over me about basses and guitars having no relationship, but this is a good example of very useful crosspolinization. Belly patches tend to wind up about the same thickness as guitar tops, so long term deflection and deformation trends are appropriate. You've got an old ply top that already is sinking and deforming. If I'm going in there for some repair work, I want to use the best materials I can to avoid a future relapse of the same problem. Red spruce and hot hide glue are the champ for this.
The upcoming spring / summer and fall issues of American Lutherie magazine will contain a series of separate ten+ page articles on vintage Kay and plywood bass restorations complete with a lot of photos that were from my Guild of American Luthier's workshop last summer in Tacoma on vintage ply restoration. In addition to patches and grafts, there is good coverage of how I use silicone heat blankets against a mold to get the collapsed top arch back into the original curvature. 'Good info for the whole community here who like the old ply beasts. Owning an old vintage Kay is a lot like owning a vintage volkswagon. They are a lot of fun and everyone has good stories to tell about them, but you need to be a good mechanic or know one if you want to use it as a daily driver!
j.
www.condino.com
coming in a few weeks:
www.kaybassrepair.com
Link Removed
This is one of the areas where I always use red or Adirondack spruce. Some folks will chime in with different opinions (around here...imagine that!!!), but my experience is that high grades of red spruce tend to be a lot stronger and stiffer than the others, and it deforms a lot less than the other spruces, to the point that it takes a bit of a learning curve to get used to it.
I work on a LOT of prewar and 19th century Martin guitars that were made with red spruce and they tend to be night vs. day different compared to anything after 1946 when they switched to sitka, so they are a very good reference in terms of what works well over the test of time. The older pre-war red spruce models tend to be about 1/3 less mass and yet they have virtually none of the deformation issues, especially behind the bridge, that the sitka models do. I'm sure the local thought police that spend all of their time on the computer and never working on instruments will likely jump all over me about basses and guitars having no relationship, but this is a good example of very useful crosspolinization. Belly patches tend to wind up about the same thickness as guitar tops, so long term deflection and deformation trends are appropriate. You've got an old ply top that already is sinking and deforming. If I'm going in there for some repair work, I want to use the best materials I can to avoid a future relapse of the same problem. Red spruce and hot hide glue are the champ for this.
The upcoming spring / summer and fall issues of American Lutherie magazine will contain a series of separate ten+ page articles on vintage Kay and plywood bass restorations complete with a lot of photos that were from my Guild of American Luthier's workshop last summer in Tacoma on vintage ply restoration. In addition to patches and grafts, there is good coverage of how I use silicone heat blankets against a mold to get the collapsed top arch back into the original curvature. 'Good info for the whole community here who like the old ply beasts. Owning an old vintage Kay is a lot like owning a vintage volkswagon. They are a lot of fun and everyone has good stories to tell about them, but you need to be a good mechanic or know one if you want to use it as a daily driver!
j.
www.condino.com
coming in a few weeks:
www.kaybassrepair.com
Link Removed
