R, My go-bar box is a four foot cube (plywood top and bottom with threaded rods in the corners holding them apart). I've cut the foam core so that three sides are solid but the front opens from the middle, which makes it less cumbersome to get into. The foam core pieces are held together by blue painter's tape. The whole thing knocks down for storage when I don't need it. I have a recycled ceramic light fixture screwed to the ceiling of the box and a low wattage bulb in the fixture. I experimented with different wattages to find what keeps the interior of the box warm without an increasing build-up of heat. You essentially want to reach an equilibrium between the heat radiated by the light bulb and the the radiation of heat out of the box into the room. So the wattage will be different depending on the size of your box, the amount of insulation around it, and the air temperature of your room. You do want some air flow so the warm moist air from gluing will vent out of the box. I just keep the box closed and the light on for several days while I'm gluing to maintain the equilibrium. That's not as good as doing the braces all at once, but I can only devote small amounts of time to this in any one day anyway.
Like you I try to work quickly when I glue on the braces, but I figure that the atmospheric humidity from the box being open is going to be less of a factor than will the moisture from the glue. I haven't gone to the trouble of putting a humidity gauge in the box because the ones available to the consumer are wildly inaccurate. I work in an art museum and the conservation staff there use lab-grade meters. They say that consumer-level meters will only give you a hazy idea of what the humidity is. Your sinuses can probably do that about as well. If I was making lutes for sale I would probably go to more trouble. Tim --- rel...@sbcglobal.net wrote: From: <rel...@sbcglobal.net> To: "Santiago Ramos-Collado" <chagorra...@yahoo.com> Cc: <lute-buil...@cs.dartmouth.edu> Subject: [LUTE-BUILDER] Re: hide glue gram strength Date: Wed, 2 Dec 2009 11:47:11 -0800 Hello Mr. Collado: The Purpose of gluing on all the braces on the soundboard at once is that it is easier then to control some very important factors. First, one wants to have the top normalized in a controlled environment with respect to humidity. The humidity in the box should be on the low side of of what you expect for the instrument to find most often . This normalization is to have the top in such a place for around 5 hours or more so that you know the top has been "stabilized" in sofar as its internal moisture is concerned. A go bar box as mentioned in earlier posts with foamcore surrounding it on all sides is also what I use. You want to work fast because when you open the box front up in order to glue and place the braces, the relative humidity will change in the box as a result of outside humidity being higher (or lower as the case may be) as well as as result of the presence of the water in the glue itself. One then seals the box as soon as possible so as to keep the relative humidity constant inside... you will want to check this from time to time... If you glue down several braces but not all, and want to come back to the project at a later date, you will have to once again stabilize the top to the EXACT humidity you used in gluing on the previous braces for 4 or 5 hours or so before continuing.. This is to say that you will want to be within a percent or so. This is actually a pain to do, so its better to brace the entire top at one go. Also if the top is only partially braced say at 35 percent and is left open in the shop even 5 or 6 percent higher or lower for any period of time, the top may well take a set and bow in one way or another creating a potato chip issue.. This is a REAL pain to flatten out. Secondly, the reason for exact humidity here is that apart from trying to prevent the top from cracking by bracing it in a slightly lower humidity than expected for the instrument, you are most importantly bracing the top with an eye (or better said 'ear') to an even dispersal of moisture interior to top, which translates to an even width across the entire top as it is being braced . This will result in a completely relaxed top with NO built in stresses as would occur if you were to apply say several braces at 35 percent, and others at 40 percent humidity at different periods of time. In this example where the humidity was at 35 percent , those braces applied will fix the width of the top to be slightly less than those sections braced where the humidity was in the 40 percent range because with more moisture in the wood the top will want to expand in width in this section, and braces put on in the 40 percent range will fix the top at this expanded width. This 5 percent differential across the top(our example) will create lateral tensions in the top which will adversely affect the sound this especially in the "tail" of the notes , which after all is where the mystery of the lute sound pretty much resides. What happens is that as the harmonics imparted to the top from the pluck of the string decays after a period of time , the energy the harmonics create begins to lessen to the degree that it will approach the level of energy embedded in top by the built in stresses .. At this point the stresses will begin to dominate and restrict the top from vibrating in accordance with the harmonics as created by the pluck. The tail of the note will hit a point in its decay and then seem to deaden in complexity, and then die altogether . In general, instruments made in this way (classical/flamenco guitars too) will tend to want only new strings - as older ones REALLY emphasize this deadening effect of a badly braced top. best r ----- Original Message ----- From: "Santiago Ramos-Collado" <chagorra...@yahoo.com> To: <qui...@earthlink.net>; <tam...@buckeye-express.com> Cc: <lute-buil...@cs.dartmouth.edu> Sent: Wednesday, December 02, 2009 9:56 AM Subject: [LUTE-BUILDER] Re: hide glue gram strength > > Greetings to all. > > I'm missing something here. What's the use of gluing all the braces at > once? > > Best regards, > > S. Ramos Collado > --- El mie 2-dic-09, tam...@buckeye-express.com > <tam...@buckeye-express.com> escribio: > > De: tam...@buckeye-express.com <tam...@buckeye-express.com> > Asunto: [LUTE-BUILDER] Re: hide glue gram strength > A: qui...@earthlink.net > Cc: lute-buil...@cs.dartmouth.edu > Fecha: miercoles, 2 diciembre, 2009, 12:53 pm > > Chad, > Well, it's a small anvil. About a foot long. A blacksmith's anvil > would definitely be overkill. I haven't actually glued on all of the > braces at one go yet, but I think I may try it on the next instrument I > build. It does sound like a bit of a circus act, though. > Re-gluing bridges (which, unfortunately, I've gotten some practice at) > is about the one thing that I do use go-bars for. I have a jig (I > think jigs outnumber power tools in my little shop) to hold the lute > horizontal and I slide it under the wall cabinets over my work bench. > Then I have little go-bars I made from strips of beech that are sized > to fit the center and the wings of a bridge. So the cabinets act as > the roof of a go-bar box, if this makes any sense. Once I've done the > gluing I slide the lute in the jig under the cabinets and stick the > go-bars between the bottom of the cabinets and the bridge. > Before gluing on the bridge I attempt to extend the working time of the > glue as much as possible by pre-warming the bridge and the bridge > location on the soundboard with an electric heating pad for about an > hour. The younger posters on this listserv may not have a heating pad > around the house, but by the time you're in your 50s you will. > I only have time to build instruments in the winter, when my basement > gets rather cold. So I've made an enclosure out of foam core for the > go-bar box (that never gets used for go-bars) and put in an electric > light to pre-warm braces and the soundboard. I assemble the box at > least a day ahead of when I'll start gluing, turn the light on inside > with the parts to be glued, and leave it that way for several days > while I'm gluing things together. The glue pot is next to the > enclosure and all of the gluing happens in the box. It also serves to > dry out the wood if there is any residual moisture. Part of the fun > for an amateur is figuring all this stuff out. > Tim > --- [1]qui...@earthlink.net wrote: > From: "Chadwick Neal" <[2]qui...@earthlink.net> > To: <[3]lute-buil...@cs.dartmouth.edu> > Subject: [LUTE-BUILDER] Re: hide glue gram strength > Date: Wed, 2 Dec 2009 09:49:09 -0500 > Hi All, > Thanks for weighing in on this topic. I've been using 315, and I think > I'm > ready to order some lower strength. It's been good to use especially > when > you want the fast tack and I've adapted my technique to suit. I would > never > be able to use Tim's method of glueing the braces all in one go and put > a > board over top with weight. An anvil, Tim??? Wow certainly not a > blacksmith's I'm assuming :-)) > No, It has a fast gel and even by the time I get the go bars on one it > has > begun to gel, one more bar and I can clean squeeze out from the first. > For bridges, I like it both in construction and repair, especially the > repair, when you have to hold the bridge by hand for several minutes. A > good > thinnish water ratio and it will hold fast. I have a really hard time > waiting the full five minutes, perhaps, too much coffee in me. I > usually > fidget around after a couple minutes. > I have veneered and all of the other operations, but you have to be > fast!! I > also like it for rib gluing, it's quick. > Shrinkage though, I witnessed a old jar with a thin layer of dried glue > crack a baby bottle! > Chad Neal > -----Original Message----- > From: [4]lute-...@cs.dartmouth.edu > [mailto:[5]lute-...@cs.dartmouth.edu] On Behalf > Of Andrew Hartig > Sent: Tuesday, December 01, 2009 4:46 PM > To: [6]lute-buil...@cs.dartmouth.edu > Subject: [LUTE-BUILDER] hide glue gram strength > I'm wondering what gram strength glue other builders out there are > using. I noticed recently that while a local luthier supply > (lmii.com) > sells 192 gram strength "high clarity" (it really does have high > transparency) hide glue as their standard for lutherie, another > general > woodworking company (toolsforworkingwood.com) markets 3 types: 192, > 251, and 315 (only the 192 comes with a "high clarity" alternative). > The only thing that really got my attention here was their > description > of the strengths, copied below: > * The 192 gram strength is a good general purpose glue, and it's > the > least expensive hide glue around. That's why it's the most > common. > Its real application is veneering, although you can use it for > regular gluing in a pinch. A lot of people consider it the best > all-around glue for general woodworking (including veneering), > because it also has the longest open time. If you are new to > hide > glue, this is the grade you should get. > * The 251 gram strength glue is traditionally the most appropriate > for regular cabinetwork. Its higher strength means that you can > do > rub joints more easily, and clamped joints will have less time > to > creep. But it's not optimal for veneering, when you'd want the > maximal amount of time for squeezing out the excess glue. > * The 192 gram strength "high clarity" is more expensive than its > cousins because it is especially refined for maximum > transparency. > It's a good all-around glue that's slightly more tacky then the > regular 192 glue. This is the glue to use if you are worried > about > visible glue lines. > * The 315 gram strength is a special purpose glue for very high > stress applications. It is favored primarily by instrument > makers > for situations where a joint will be under constant force. Of > the > glues the 315 has the shortest open time. > So, is 192 not strong enough for lutherie, as implied by the > description of the 315? Or is the concern here more about > high-tension > modern instruments? > What are others using? > (As an aside, I should mention that I've had no troubles so far with > using the high clarity 192.) > Curiously, > Andrew > -- > To get on or off this list see list information at > [7]http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > __________________________________________________________________ > > !Obten la mejor experiencia en la web! > Descarga gratis el nuevo Internet Explorer 8 > http://downloads.yahoo.com/ieak8/?l=e1 -- > > References > > 1. http://e1.mc582.mail.yahoo.com/mc/compose?to=qui...@earthlink.net > 2. http://e1.mc582.mail.yahoo.com/mc/compose?to=qui...@earthlink.net > 3. > http://e1.mc582.mail.yahoo.com/mc/compose?to=lute-buil...@cs.dartmouth.edu > 4. > http://e1.mc582.mail.yahoo.com/mc/compose?to=lute-...@cs.dartmouth.edu > 5. > http://e1.mc582.mail.yahoo.com/mc/compose?to=lute-...@cs.dartmouth.edu > 6. > http://e1.mc582.mail.yahoo.com/mc/compose?to=lute-buil...@cs.dartmouth.edu > 7. http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > N� ��讇߶��+-�祊�b��+��b�v���i��0�� j�f��ayۿ��?��^i٢���u�a�i
