[LUTE-BUILDER] Re: Archlute Bridge
Hi--I am sure that the bridge is ebony because I have drilled/enlarged several holes on it and its black dust all the way though. I am worried about the braces and the soundboard. Here in Utah the humidity often gets as low as 5-10%(like today). I am still looking for someone to do the work on this lute. Any ideas? --Sterling From: Richard Lees To: Dana Emery ; "lute-buil...@cs.dartmouth.edu" Sent: Monday, June 18, 2012 8:12 PM Subject: [LUTE-BUILDER] Re: Archlute Bridge As usual, Dana Emery strikes again ! Excellent post ... excellent post... Sonically too, Ebony is not the most musical of woods and while I have retopped a beautiful archlute for a player out here which had ebony staves, one could lightly sense the enharmonic character of ebony in its sound... now for bridges, Dana is right with respect to correct build procedures ..But if our mystery bridge turns out to actually be ebony ( and I have seen some pretty strange stuff done in our modern era with lutes) now would be the best time to replace it I especially like Dana's suggestion to check all joints ! In the retopping of the archlute I mentioned above MANY braces (well over half!) had crystalized glue joints and so I had to re-brace the entire instrument. This instrument which was made by a pretty well known luthier was built in the late 70s. AND if the top is pushing 20 plus years , Dana's additional suggestion of simply putting on a new top is indeed called for... A last note to Dana's post some years ago i posted a quick observation on cracks, and its worth mentioning it again. And Dana is yet again right on target The Spanish masters of lutherie during the mid 60s many of whom I had the great honor to know , were absolutely firm on this issue.. We are to brace perhaps 5 or 6 percent LOW with respect to the expected humidity the instrument is going typically see This is to insure the health of the top and to make sure the top sounds well too. BUT there is another monster lurking here.. If the players don't also agressively monitor EXCESSIVE HUMIDITY as when when the relative humidity is in excess of say 20 percent of the build target, then the wood will expand accordingly ... Now since the plantilla or shape of the instrument is fixed by the braces and bowl , the softer top, as it expands, has no where to go... What happens then is that the wood first bellies upwards and then starts to crush itself, under these high humidity conditions and then, when the humidity drops , the top can REALLY crack, and whats worse, at a higher level of humidity even than the target build point! This occurs because by virtue of have been laterally crushed, the top is fundamentally NARROWER than before. When the humidity drops and the top shrinks even further, these catastrophic failures can occur. I restored several German harp guitars like this... The back of one of them, a Haberman instrument, had shrunk so badly that it lost over1/4 of an inch in width relative to plantilla so that when I removed the back you could hear the instrument groan as the stresses were relieved and the sides started to reconform . If this is what has happened to Sterling's lute, then i am afraid a new top is indeed in order.. Richard Lees On 6/18/2012 3:32 PM, Dana Emery wrote: > First point, much of that which is black on musical instruments is dyed maple and not ebony proper. The wood used for a lute bridge does need to stand up to the strings, but need not be as stiff as ebony, fruitwood (pear, plum, apple) are recomended from what I recall. > As has been pointed out your enemy is thermal mass. A replacement strategy allows destructive removal. Working on the naked top will allow the other repair you want to do, and in general you can rejuvinate all the joints as you wish. > cracks in the top of a lute are troublesome, and likely when an instrument travels to a drier climate than that it was built in (er, designed for). A piano top is designed to have a slight but crucial arch that keeps all the joints in compression as it dries out. lute tops are flatter than can allow that, and actually cave in in places (especially between bridge and rose); rising in others (below bridge). > An entirely new top might not be a bad idea at this point, but you seem inexperienced for that, still should you have the resources, it might be an opportunity to consider exploring. You will want to make thickness measuring calipers as well as a go-bar deck and perhaps some other specialist tools. The scrape of the present instrument can be used for a model. You might look for a violin maker in your area to share a brew or two with and get some info
[LUTE-BUILDER] Re: Archlute Bridge
As usual, Dana Emery strikes again ! Excellent post ... excellent post... Sonically too, Ebony is not the most musical of woods and while I have retopped a beautiful archlute for a player out here which had ebony staves, one could lightly sense the enharmonic character of ebony in its sound... now for bridges, Dana is right with respect to correct build procedures ..But if our mystery bridge turns out to actually be ebony ( and I have seen some pretty strange stuff done in our modern era with lutes) now would be the best time to replace it I especially like Dana's suggestion to check all joints ! In the retopping of the archlute I mentioned above MANY braces (well over half!) had crystalized glue joints and so I had to re-brace the entire instrument. This instrument which was made by a pretty well known luthier was built in the late 70s. AND if the top is pushing 20 plus years , Dana's additional suggestion of simply putting on a new top is indeed called for... A last note to Dana's post some years ago i posted a quick observation on cracks, and its worth mentioning it again. And Dana is yet again right on target The Spanish masters of lutherie during the mid 60s many of whom I had the great honor to know , were absolutely firm on this issue.. We are to brace perhaps 5 or 6 percent LOW with respect to the expected humidity the instrument is going typically see This is to insure the health of the top and to make sure the top sounds well too. BUT there is another monster lurking here.. If the players don't also agressively monitor EXCESSIVE HUMIDITY as when when the relative humidity is in excess of say 20 percent of the build target, then the wood will expand accordingly ... Now since the plantilla or shape of the instrument is fixed by the braces and bowl , the softer top, as it expands, has no where to go... What happens then is that the wood first bellies upwards and then starts to crush itself, under these high humidity conditions and then, when the humidity drops , the top can REALLY crack, and whats worse, at a higher level of humidity even than the target build point! This occurs because by virtue of have been laterally crushed, the top is fundamentally NARROWER than before. When the humidity drops and the top shrinks even further, these catastrophic failures can occur. I restored several German harp guitars like this... The back of one of them, a Haberman instrument, had shrunk so badly that it lost over1/4 of an inch in width relative to plantilla so that when I removed the back you could hear the instrument groan as the stresses were relieved and the sides started to reconform . If this is what has happened to Sterling's lute, then i am afraid a new top is indeed in order.. Richard Lees On 6/18/2012 3:32 PM, Dana Emery wrote: First point, much of that which is black on musical instruments is dyed maple and not ebony proper. The wood used for a lute bridge does need to stand up to the strings, but need not be as stiff as ebony, fruitwood (pear, plum, apple) are recomended from what I recall. As has been pointed out your enemy is thermal mass. A replacement strategy allows destructive removal. Working on the naked top will allow the other repair you want to do, and in general you can rejuvinate all the joints as you wish. cracks in the top of a lute are troublesome, and likely when an instrument travels to a drier climate than that it was built in (er, designed for). A piano top is designed to have a slight but crucial arch that keeps all the joints in compression as it dries out. lute tops are flatter than can allow that, and actually cave in in places (especially between bridge and rose); rising in others (below bridge). An entirely new top might not be a bad idea at this point, but you seem inexperienced for that, still should you have the resources, it might be an opportunity to consider exploring. You will want to make thickness measuring calipers as well as a go-bar deck and perhaps some other specialist tools. The scrape of the present instrument can be used for a model. You might look for a violin maker in your area to share a brew or two with and get some informal counseling. Good luck To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
[LUTE-BUILDER] Re: Archlute Bridge
Hello Chris and Sterling et allus! I have been off this thread as I have been out of town for the last several days... To answer Chris's question, NO , one does not abrade/plane the bridge off the soundboard at all. The problem we face is that wood is an excellent thermal sink, and as much vertical mass as a bridge has - being 5 to 7 mm high or thereabouts from treble to bass on a Baroque instrument- its near impossible to wet and heat the bridge itself and have the heat and moisture pass through the bridge onto the glue joint and loosen same. You could be there applying heat and moisture for hours and the minute you remove the iron, the joint will immediately cool down and the bond will reset before you can separate the bridge from the top even a little bit !!! In fact, in this scenario, the only workable solution I know if is that you must heat a sharpened oil painting palette knife (a REALLY THIN ONE! ) while trying to slip it under a an ear seriously wetted with hot water where you test to see if the joint is opening with a single edge razor blade, this in order to start the process. Then, if you are successful, and can gently slip the palette knife underneath the ear a little, you add more hot water in front of the knife ( which you must continually reheat as you work) and as you gently push the knife down the length of the bridge you must wet and heat as you go. .. This is dangerous because the bridge being relatively thick will not give as the knife is passing underneath. The only thing than can "pull away" from the underneath of the bridge as the bond is hopefully loosened, is the top itself. If the bond is even marginally holding as you are pushing the knife underneath it you can very easily cause tearout of the moistened top as I indicated in my first email and believe me , you DON'T want this. Also its hard to control the water and keep it confined to a small area. If you want, therefore, to save the bridge you are currently removing, I believe you really have no choice but to remove the top completely so you can apply heat and moisture from the BOTTOM of the top directly under the bridge into the bond area. Here you have several things working for you. Thing one : The top should be around 1.75 to perhaps as much as 1.95 mills here, NOT 5 to 7 mills thick as is the bridge. Thing two: Here the top is MUCH more porous than the bridge and will absorb water much more freely into the wood so that you can actually affect the bond directly. NOW If you don't need to save the bridge then, it makes sense to plane it down. This is done NOT TO REMOVE IT , but to get it as THIN as possible. In this way, the heat and moisture will penetrate the remainder of the bridge successfully (now only about 1 mill or so thick) and really loosen the bond . Also, if the top is off, you can work it from both top AND bottom as well and be even more effective in loosening the bond with water and heat , and also keep the work area small. Lastly, because the bridge remainder is now very thin, it will also be flexible (especially being water soaked) and therefore will be much easier to lift off as the knife passes between it and the top, and will lessen the chances of pulling up wood from the top . On 6/15/2012 10:13 PM, Chris Newman wrote: Question from a newbie with zero experience. Could one laboriously plane/ abrade the bridge off the soundboard? Chris To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
[LUTE-BUILDER] Re: Archlute Bridge
ld
immediately split it (the total tension on a medium sized Celtic harp is
over a thousand pounds). To make a solid soundboard in one piece would
require a tree of four feet diameter, so they take the solid pieces and
put a backing on them - which is a laminate anyway. Which comes back to
the split in the lute soundboard, and the "new wood" by gluing with
sawdust. Doesn't seem to have affected the sound of "solid" soundboard
harps.
One wants to maintain the integrity of the vibrations within the wood,
and from one part of the body to another. Small variations won't be
heard, it is the overall resonance that is important. I think it is
important to understand where that resonance comes from in the various
instruments - and they are not all the same. The final object it to put
a sound in the air (neglecting amplification and pickups as that is
another matter, and one I'm adamant on - music is changed as soon as it
passes through any device, even if it is perfectly recorded it still
depends on the ability of the speakers, and subtlety is lost). There is
but one device that properly interprets the mixed vibrations that we
call musical sound, and I'm in awe of it. The human ear can hear a mix
of vibrations and separate them, and the auditory portion of the human
brain can re-assemble them into the individual sounds. Think of it, you
couldn't do that with the best of computers and Fourier analysis. You
could break out the individual sine waves of the mixture, but you'd
never know which came from the oboe or the flute. It is the re-assembly
that is magnificent.
Best, Jon
On 6/15/2012 4:47 AM, sterling price wrote:
Richard--thanks very much---this is just the sort of info I was looking
for.
Taking a lute apart sort of scares me--the fear is I will just ruin
it. This lute has other issues--it came from England to very dry Utah
18 years ago and the soundboard developed a split at the seam soon
after it got here. Now the split goes almost the whole top but it has
not hurt playability. Perhaps I should just make a new soundboard
I will keep you all posted on what I do.
--Sterling
From: Richard Lees
To: sterling price;
"lute-buil...@cs.dartmouth.edu"
Sent: Friday, June 15, 2012 12:03 AM
Subject: [LUTE-BUILDER] Re: Archlute Bridge
Hello Sterling!!
Its been a long time posting for me, I have been pretty busy with
work...
I offer what I have done in the past.
Many of the EXCELLENT builders who post here will no doubt have
wonderful input to give you , no doubt..
For my part, having replaced a number of bridges in restoration work
as well as gluing on bridges in new construction, I would say
It is much better to remove the top. MUCH BETTER in fact
Your description is good by the way, and certainly justifies replacing
the bridge.
Also since the current bridge is not to be kept, you do have a great
advantage here.
However there are issues .
Removing a well glued on bridge is no easy task. Heat and moisture are
required and the application of these forces can easily damage a top
beyond repair...
After you remove the top from the bowl , you must focus the heat and
moisture very carefully, and take extreme caution not to be impatient
and lift up the bridge with any force as this could create tear outs in
the top underneath. This situation is a nightmare to deal with , but
CAN be addressed if the damage is shallow.
Given that you are going to make a new bridge, I suggest that you
begin by removing whatever top detail has been placed on the top of the
old bridge ( if any) and then to CAREFULLY plane down the old bridge
with a block plane to where the remaining bridge is perhaps 1.5 mills
thick or less if you can ...
Now you can place hot water on a rag cut to fit EXACTLY on top of the
remaining bridge with a LITTLE overlap and then cover the cloth with
tin foil or saran wrap to prevent the water from evaporating. Please
leave this in place for a while .
As thin as the remainder of the bridge now is, the water and heat
should penetrate fairly well into the top and glue joint underneath,
and begin to loosen the bond.
Now under one of the ears see if you can't slip a single edged razor
blade between the bottom of the bridge and the top... You must not
force this if there is any resistance you should stop immediately!
You will need to apply more heat and moisture using hot water and a
SMALL iron directly on the top of the remainder of the bridge on the
area where you wish to start, and try again... I stress that it is
important to be careful to control how much heat and moisture is
absorbed in the top and most importantly to keep this in area as close
to the perimeter of the bridge as possible.
[LUTE-BUILDER] Re: Archlute Bridge
Question from a newbie with zero experience. Could one laboriously plane/ abrade the bridge off the soundboard? Chris On 16 Jun 2012, at 03:51, Sterling wrote: > Hi- from what you all are saying about this, it seems that it is probably > beyond my abilities to attempt this. I would certainly learn a lot from the > process but I really don't want to ruin this lute. I have already done a lot > to it like converting it from twelve to fourteen courses(with octaves). > Might I ask if there is someone on this list who would be willing to do the > bridge replacement on this lute? I could send it anywhere in the US... > Sterling > > Sent from my iPhone > > On Jun 15, 2012, at 10:36 AM, "Ted Woodford" wrote: > >> I'll add my two cents, though Richard provided a wealth of ideas. Planing >> down the existing bridge is an excellent tactic! I find aliphatic glues >> (white or yellow) actually easier to remove than hide glue. They often come >> loose without the addition of water. I put a several layers of aluminum foil >> over the top around the bridge for insulation when heating it. I use a >> regular household iron for that. >> >> It's possible to glue on the replacement bridge using hot hide glue and a >> rubbed joint. I believe many Spanish guitar makes have used this method. It >> takes advantage of the glues' tendency to contract and pull things together >> as dries. Basically one slides the two parts back and forth a couple of >> times while the glue is hot, creating a suction not unlike what happens if >> you rub two microscope slides together. The repairperson then holds it >> firmly in place until the glue has gelled. It takes a couple of minutes. >> >> If the seam is open it might be just as well to patch it with a spline of >> spruce while the bridge and strings are off. It's not likely to ever close >> by itself in the dry atmosphere of Utah! Richard's observations on humidity >> control are excellent. Fixing the open seam would seem prudent if you decide >> to separate the top from the bowl to apply clamps to the new bridge. There >> should be enough flex in the top that total separation from the bowl isn't >> strictly necessary. Freeing it up to the level of the third bar should leave >> an opening wide enough to get some lightweight deep throat clamps in there. >> >> The main thing is to map out the geometry before starting. What angle does >> the neck take relative to the face under string tension? Is there an >> appreciable bulging behind the bridge that disappears when the strings are >> slackened? Pay close attention to the height of the string holes over the >> soundboard while it is strung to pitch and use them as a guide for >> calculation. >> -Ted >> >> - Original Message - From: "sterling price" >> To: >> Sent: Friday, June 15, 2012 12:27 AM >> Subject: [LUTE-BUILDER] Archlute Bridge >> >> >>> Hi-I'm not sure if this list is still active so here goes---I have a >>> small archlute with a bridge that is made of ebony and I would like to >>> replace it with something more appropriate. Also because the string >>> spacing and action is all wrong. My question is--what is involved in >>> removing a bridge and replacing it without removing the soundboard? I >>> just need some advice on how to proceed, or if I should leave it alone. >>> >>> --Sterling >>> >>> -- >>> >>> >>> To get on or off this list see list information at >>> http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html >> >> > >
[LUTE-BUILDER] Re: Archlute Bridge
Hi- from what you all are saying about this, it seems that it is probably beyond my abilities to attempt this. I would certainly learn a lot from the process but I really don't want to ruin this lute. I have already done a lot to it like converting it from twelve to fourteen courses(with octaves). Might I ask if there is someone on this list who would be willing to do the bridge replacement on this lute? I could send it anywhere in the US... Sterling Sent from my iPhone On Jun 15, 2012, at 10:36 AM, "Ted Woodford" wrote: > I'll add my two cents, though Richard provided a wealth of ideas. Planing > down the existing bridge is an excellent tactic! I find aliphatic glues > (white or yellow) actually easier to remove than hide glue. They often come > loose without the addition of water. I put a several layers of aluminum foil > over the top around the bridge for insulation when heating it. I use a > regular household iron for that. > > It's possible to glue on the replacement bridge using hot hide glue and a > rubbed joint. I believe many Spanish guitar makes have used this method. It > takes advantage of the glues' tendency to contract and pull things together > as dries. Basically one slides the two parts back and forth a couple of times > while the glue is hot, creating a suction not unlike what happens if you rub > two microscope slides together. The repairperson then holds it firmly in > place until the glue has gelled. It takes a couple of minutes. > > If the seam is open it might be just as well to patch it with a spline of > spruce while the bridge and strings are off. It's not likely to ever close by > itself in the dry atmosphere of Utah! Richard's observations on humidity > control are excellent. Fixing the open seam would seem prudent if you decide > to separate the top from the bowl to apply clamps to the new bridge. There > should be enough flex in the top that total separation from the bowl isn't > strictly necessary. Freeing it up to the level of the third bar should leave > an opening wide enough to get some lightweight deep throat clamps in there. > > The main thing is to map out the geometry before starting. What angle does > the neck take relative to the face under string tension? Is there an > appreciable bulging behind the bridge that disappears when the strings are > slackened? Pay close attention to the height of the string holes over the > soundboard while it is strung to pitch and use them as a guide for > calculation. > -Ted > > - Original Message - From: "sterling price" > To: > Sent: Friday, June 15, 2012 12:27 AM > Subject: [LUTE-BUILDER] Archlute Bridge > > >> Hi-I'm not sure if this list is still active so here goes---I have a >> small archlute with a bridge that is made of ebony and I would like to >> replace it with something more appropriate. Also because the string >> spacing and action is all wrong. My question is--what is involved in >> removing a bridge and replacing it without removing the soundboard? I >> just need some advice on how to proceed, or if I should leave it alone. >> >> --Sterling >> >> -- >> >> >> To get on or off this list see list information at >> http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html > >
[LUTE-BUILDER] Re: Archlute Bridge
I'll add my two cents, though Richard provided a wealth of ideas. Planing down the existing bridge is an excellent tactic! I find aliphatic glues (white or yellow) actually easier to remove than hide glue. They often come loose without the addition of water. I put a several layers of aluminum foil over the top around the bridge for insulation when heating it. I use a regular household iron for that. It's possible to glue on the replacement bridge using hot hide glue and a rubbed joint. I believe many Spanish guitar makes have used this method. It takes advantage of the glues' tendency to contract and pull things together as dries. Basically one slides the two parts back and forth a couple of times while the glue is hot, creating a suction not unlike what happens if you rub two microscope slides together. The repairperson then holds it firmly in place until the glue has gelled. It takes a couple of minutes. If the seam is open it might be just as well to patch it with a spline of spruce while the bridge and strings are off. It's not likely to ever close by itself in the dry atmosphere of Utah! Richard's observations on humidity control are excellent. Fixing the open seam would seem prudent if you decide to separate the top from the bowl to apply clamps to the new bridge. There should be enough flex in the top that total separation from the bowl isn't strictly necessary. Freeing it up to the level of the third bar should leave an opening wide enough to get some lightweight deep throat clamps in there. The main thing is to map out the geometry before starting. What angle does the neck take relative to the face under string tension? Is there an appreciable bulging behind the bridge that disappears when the strings are slackened? Pay close attention to the height of the string holes over the soundboard while it is strung to pitch and use them as a guide for calculation. -Ted - Original Message - From: "sterling price" To: Sent: Friday, June 15, 2012 12:27 AM Subject: [LUTE-BUILDER] Archlute Bridge Hi-I'm not sure if this list is still active so here goes---I have a small archlute with a bridge that is made of ebony and I would like to replace it with something more appropriate. Also because the string spacing and action is all wrong. My question is--what is involved in removing a bridge and replacing it without removing the soundboard? I just need some advice on how to proceed, or if I should leave it alone. --Sterling -- To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
[LUTE-BUILDER] Re: Archlute Bridge
I'll start the ball rolling - The critical thing is what kind of glue was used to attach it to the soundboard. If it's synthetic, there's no easy way to get it off. If hide glue was used, alcohol can dissolve it, though you need to be careful because it can also ruin the finish of the instrument - particularly if it is French polished. For what it's worth, I'd do my best to preserve the original soundboard. I believe that older wood is generally better than what we can get nowadays. It IS possible to take off a soundboard, perform repairs, and put it back carefully without making too much of a mess of things. Any signs of repair are, I believe, honourable features of a mature lute. At least that's how the old ones liked them. Bill __ From: sterling price To: "lute-buil...@cs.dartmouth.edu" Sent: Friday, 15 June 2012, 5:27 Subject: [LUTE-BUILDER] Archlute Bridge Hi-I'm not sure if this list is still active so here goes---I have a small archlute with a bridge that is made of ebony and I would like to replace it with something more appropriate. Also because the string spacing and action is all wrong. My question is--what is involved in removing a bridge and replacing it without removing the soundboard? I just need some advice on how to proceed, or if I should leave it alone. --Sterling -- To get on or off this list see list information at [1]http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html -- References 1. http://www.cs.dartmouth.edu/%7Ewbc/lute-admin/index.html
[LUTE-BUILDER] Re: Archlute Bridge
Richard--thanks very much---this is just the sort of info I was looking for. Taking a lute apart sort of scares me--the fear is I will just ruin it. This lute has other issues--it came from England to very dry Utah 18 years ago and the soundboard developed a split at the seam soon after it got here. Now the split goes almost the whole top but it has not hurt playability. Perhaps I should just make a new soundboard I will keep you all posted on what I do. --Sterling From: Richard Lees To: sterling price ; "lute-buil...@cs.dartmouth.edu" Sent: Friday, June 15, 2012 12:03 AM Subject: [LUTE-BUILDER] Re: Archlute Bridge Hello Sterling!! Its been a long time posting for me, I have been pretty busy with work... I offer what I have done in the past. Many of the EXCELLENT builders who post here will no doubt have wonderful input to give you , no doubt.. For my part, having replaced a number of bridges in restoration work as well as gluing on bridges in new construction, I would say It is much better to remove the top. MUCH BETTER in fact Your description is good by the way, and certainly justifies replacing the bridge. Also since the current bridge is not to be kept, you do have a great advantage here. However there are issues . Removing a well glued on bridge is no easy task. Heat and moisture are required and the application of these forces can easily damage a top beyond repair... After you remove the top from the bowl , you must focus the heat and moisture very carefully, and take extreme caution not to be impatient and lift up the bridge with any force as this could create tear outs in the top underneath. This situation is a nightmare to deal with , but CAN be addressed if the damage is shallow. Given that you are going to make a new bridge, I suggest that you begin by removing whatever top detail has been placed on the top of the old bridge ( if any) and then to CAREFULLY plane down the old bridge with a block plane to where the remaining bridge is perhaps 1.5 mills thick or less if you can ... Now you can place hot water on a rag cut to fit EXACTLY on top of the remaining bridge with a LITTLE overlap and then cover the cloth with tin foil or saran wrap to prevent the water from evaporating. Please leave this in place for a while . As thin as the remainder of the bridge now is, the water and heat should penetrate fairly well into the top and glue joint underneath, and begin to loosen the bond. Now under one of the ears see if you can't slip a single edged razor blade between the bottom of the bridge and the top... You must not force this if there is any resistance you should stop immediately! You will need to apply more heat and moisture using hot water and a SMALL iron directly on the top of the remainder of the bridge on the area where you wish to start, and try again... I stress that it is important to be careful to control how much heat and moisture is absorbed in the top and most importantly to keep this in area as close to the perimeter of the bridge as possible.. If you have removed the top, of course you can apply moisture and heat from UNDERNEATH the top just below bridge, and be very effective as the top itself is more porous than the ebony. Carefully move the razor blade along the joint until the bridge remainder lifts up completely along its length At this point I recommend damping the top at least around the area where there has been heat with cold water and prefer myself , to damp the entire top - top and bottom to equalize the tensions so as to to help avoid selective shrinking of the top and the ensuing warps that will incur as a result. If you do damp the entire top , AVOID the ROSE TOP AND BOTTOM Just after the top has been damped, I then place the top (topside down ) in a go bar box ( you must use some cellotape on the go bar box bottom where the bridge area is going to be , so that the remaining glue in the bridge area of the top doesn't bond it to the box) and then using cellotaped bars of your manufacture (say 1/2 x 1 x 12 inches or so) go bar clamp these bars down across where the bridge was located to ensure that the top is flat in this critical area. Also brace the existing lateral braces of the top by placing go bars in the center of each of these lateral braces and at each end , and put go bars on the J bar as well as the treble bars I recommend leaving it like this for several days until the top has stabilized, is flat, and all moisture you have put into the top is gone. Now comes an interesting thing.. The new bridge should actually be glued on with the top with the same humidity as when all the braces were glued down in the first place. This is to p
[LUTE-BUILDER] Re: Archlute Bridge
Hello Sterling!! Its been a long time posting for me, I have been pretty busy with work... I offer what I have done in the past. Many of the EXCELLENT builders who post here will no doubt have wonderful input to give you , no doubt.. For my part, having replaced a number of bridges in restoration work as well as gluing on bridges in new construction, I would say It is much better to remove the top. MUCH BETTER in fact Your description is good by the way, and certainly justifies replacing the bridge. Also since the current bridge is not to be kept, you do have a great advantage here. However there are issues . Removing a well glued on bridge is no easy task. Heat and moisture are required and the application of these forces can easily damage a top beyond repair... After you remove the top from the bowl , you must focus the heat and moisture very carefully, and take extreme caution not to be impatient and lift up the bridge with any force as this could create tear outs in the top underneath. This situation is a nightmare to deal with , but CAN be addressed if the damage is shallow. Given that you are going to make a new bridge, I suggest that you begin by removing whatever top detail has been placed on the top of the old bridge ( if any) and then to CAREFULLY plane down the old bridge with a block plane to where the remaining bridge is perhaps 1.5 mills thick or less if you can ... Now you can place hot water on a rag cut to fit EXACTLY on top of the remaining bridge with a LITTLE overlap and then cover the cloth with tin foil or saran wrap to prevent the water from evaporating. Please leave this in place for a while . As thin as the remainder of the bridge now is, the water and heat should penetrate fairly well into the top and glue joint underneath, and begin to loosen the bond. Now under one of the ears see if you can't slip a single edged razor blade between the bottom of the bridge and the top... You must not force this if there is any resistance you should stop immediately! You will need to apply more heat and moisture using hot water and a SMALL iron directly on the top of the remainder of the bridge on the area where you wish to start, and try again... I stress that it is important to be careful to control how much heat and moisture is absorbed in the top and most importantly to keep this in area as close to the perimeter of the bridge as possible.. If you have removed the top, of course you can apply moisture and heat from UNDERNEATH the top just below bridge, and be very effective as the top itself is more porous than the ebony. Carefully move the razor blade along the joint until the bridge remainder lifts up completely along its length At this point I recommend damping the top at least around the area where there has been heat with cold water and prefer myself , to damp the entire top - top and bottom to equalize the tensions so as to to help avoid selective shrinking of the top and the ensuing warps that will incur as a result. If you do damp the entire top , AVOID the ROSE TOP AND BOTTOM Just after the top has been damped, I then place the top (topside down ) in a go bar box ( you must use some cellotape on the go bar box bottom where the bridge area is going to be , so that the remaining glue in the bridge area of the top doesn't bond it to the box) and then using cellotaped bars of your manufacture (say 1/2 x 1 x 12 inches or so) go bar clamp these bars down across where the bridge was located to ensure that the top is flat in this critical area. Also brace the existing lateral braces of the top by placing go bars in the center of each of these lateral braces and at each end , and put go bars on the J bar as well as the treble bars I recommend leaving it like this for several days until the top has stabilized, is flat, and all moisture you have put into the top is gone. Now comes an interesting thing.. The new bridge should actually be glued on with the top with the same humidity as when all the braces were glued down in the first place. This is to prevent stresses from being introduced into the top which will will deaden the sound. Since we have most likely no record of what this humidity figure was , we now have a bit of a mystery !~!!! In one lute I worked on and which needed a complete bridge re gluing - the bridge was lifting up under the ears and also under the first course but was otherwise perfect, my client wanted to reuse the original bridge. This instrument by the way was made by a well known and well respected American luthier. As such, I faced this problem of not knowing the relative humidity used during the gluing of the braces I discovered that keeping the top in a go bar box at 44 percent humidity to start with, the top developed a bow with the center of the top depressed relative to the edges, and this within less than 20 minutes from removing the go
