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I'm figuring out the bridge for the Torres guitar. I have the Stauffer with the same strings, and I think it only has 0mm -1mm stretch on the scale, but I wanted to double check the tune. Ahh, it is upstairs on the little uke that is on the back burner.

Well. That's not right!



Yes. It happened again. A baroque bridge that won't stay in place. HHG. This one was glued on first, before anything else; the lower area didn't get glued; I don't know what happened there, moved in clamping? Need a moulded caul for it? But it did rip out spruce fibers.

In the winter it goes down to 40% usually in the winter in the basement. Maybe 37 upstairs. It's been around 35 downstairs; but it's been snowing too. Right now it is 9, with 67% humidity. That still doesn't seem like a catastrophic humidity range.

So what's the problem? the Stauffer is fine. It does have a larger footprint, maybe a little smaller than the Torres, because the ends are moustachioed. It doesn't happen in summer. I had the first little baroque guitar playing all summer.

Is Titebond less subject to drying out in lower humidity? I usually try to size the joints first, and then glue. I did notice on a video by a violin maker, Sofia Vittore, that she lets A LOT of glue soak into a joint before she glues them. This was in a recent video in the winter. Like Ken Parker soaking Epoxy into the wood as a sealer/finish. She went until the wood was not dry.

Is doing that a thing? I've never seen it before, only sizing with very thin glue; but that is what she was doing with Poplar Cello ribs.

Ahh. Today, with this stupid cold weather, it s 30% and 51 downstairs. It was 49 degrees when I went down.I warmed it up! Upstairs it is. 66 and 31% after about 15 minutes. We went out yesterday, and it was 2 degrees, with blowing, very fine snow, almost whiteouts. My wife freaks out. It's no big deal.

Any suggestions?

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Why be normal?

It looks like the fit wasn’t perfect. HHG doesn’t fill gaps. There appears to be glue on the tail end of the footprint that didn’t bond to the bridge. In other words, there was a gap there. Sometimes it’s hard to get the fit perfect, but it’s necessary.

This is all basic stuff that you already know: One of the good features of HHG is the brittleness that allows a bridge to pop. Wood shrinks and swells across the grain. The grain of the bridge is at right angles to the grain of the top. When the top gets smaller across, the bridge doesn’t shrink along its length. The pop off may have prevented a crack. 30% is low enough to cause damage when parts were glued in a 40+ % environment.

Titebond is a bit more flexible than HHG, so it may hold better when humidity shrinks the wood. I use HHG on any joint that will be under stress. I’d rather have the joint pop than creep.

I can't see any glue residue on the back part of the bridge or that part of the top. Is it possible that you simply didn't apply glue all across the bridge base?

Another HHG gotcha this time of year is forgetting about the air temperature. I reglued a bridge with HHG on Wednesday, and it peeled off as soon as I strung it up on Thursday. The glue had gelled before I got the bridge clamped down. Redid it properly yesterday, warming the parts before glueing, and it's holding fine today.

When you have a small foot print bridge such as this one it's even more imperative to expand the wood-to-wood gluing area as much as possible. We take it to 0.005 - 0.010" of the perimeter of the bridge foot print. We still want some finish under the bridge so it does not look sloppy.

You can do a forensic examination of this one from the residue and you have very little wood-to-wood gluing area that you took advantage of. I would estimate that there is 40 - 50% more area that could have been glued here.

Additionally the back edge of the bridge's gluing footprint is the money area where all the heavy lifting is done and that had no glue residue on it at all.

Some here get upset when I suggest that people who do not have a lot of experience with HHG or can't for one reason of another strictly adhere of the requirements of HHG use go with Titebond original even on a bridge. I'll trade any possibility of cold creep in time which I've rarely seen by the way when considering Titebond Original for gelled HHG or improper fit, clamping, glue freshness, room temp, etc... any time. Titebond is easier to be successful with and more forgiving.

But you still have to clamp both HHG and Titebond Original well and I don't see how with this body that may have happened. If the sound hole was open and your long clamps had any flex at all clamping pressure and distribution was insufficient.

Lastly this did not happen because Titebond does something better than HHG. This happened likely because the gluing area was too small.

I'll add what's happening right now here in Michigan. We just rose above the -8F we had yesterday and it's been VERY cold and very dry. Both Titebond and HHG will characteristically throw bridges when the RH where the instrument is falls below 40%. We certainly have this weather now.

I ask people here for years how they know that the RH is this or that and they tell me they have a digital hygrometer which is as useful as a glass hammer.... They are inherently inaccurate and when by chance you can find one that is accurate they drift in 3 years or less because they are based on an electro chemical reaction that the chemicals deteriorate over time.

So there is no substitute for wet bulb testing or any of the dozen or so variations on this theme. Get a quality hygrometer that is mechanical and can be tuned and use a wet bulb to calibrate. Do it twice a year until you understand how much drift your hygrometer may do.

We have a $6K new instrument in the shop that has a design where you can't clamp the bridge. It's in the shop because the bridge came off.... And it came off because the design did not afford the poor thing the opportunity to have the crap clamped out of the bridge during installation.

I think that this may be some of the case here as well as it happening right now here in Michigan suggests RH requirements saw an opportunity to strike and there were other problems too providing the opportunity for the bridge to lift. String tension is constant and always looking to make an instrument fail.

A well glued bridge with HHG can easily last a couple hundred years. I've seen Egyptian furniture in a museum that was glued with HHG and was 2,000 years old and the glue is still holding. But again you have to use it strictly in accordance with its requirements or it will surely bite you and not I am not calling you Shirley Ken.

The 1867 Martin that we spent 2 years restoring still had the original bridge glued on well with the original HHG.

We only use HHG when our shop is 72Fish, the RH is a calibrated 42-48 percent. We have all clamps in place in 15 seconds or less WITH preheating and the parts have to fit perfectly or it won't hold. There is no gap filling with HHG it will fail if there is not wood-to-wood contact.

Use HHG in accordance with its requirements and it will serve us better than any other glue we know of. If any of the requirements are not met it is likely to fail.

This is again why I suggest to people building early guitars and not experienced with HHG the world is not going to end if you use Titebond Original. One builder I know gets $35K for his guitars and they re made with all Titebond Original.

The problem with the baroque instruments, is that you can't get in the soundhole. That's why you glue them first! Even if you could, the hole is pretty small.

I measure a little less than 30% that wasn't touching. It has to be that it was just not fit. I will try again; but certainly not now, it is just too cold, even heating both pieces up with a heat gun. I will make sure that both parts are really soaked, and then rub, and hold in place.

The whole shrinking and swelling stuff. Yesterday my archtop played nice at 1, and 1.5mm. Today I had to move the truss rod for a little more bend; just a tiny bit to make it play. There is usually 1 day a year that some violins loose their strings from the pegs slipping! More than half of them never have that problem, and are almost always in tune. I'll have to look at them to see what they have that the other ones don't have.

I don't really like the feel of the Grover Uke tuners I have on the archtop. Too much play, and not much feel. Yeah, they were cheap.

My wife said that she heard when the bridge snapped off. Thought it sounded like a mousetrap.

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Why be normal?

I use a vacuum clamp for gluing bridges. It’s much quicker and easier than aligning cauls and clamps as the glue cools.

30% is less than I see from your pictures and again the entire back edge of the bridge where most of the work is done has no glue residue at all.

It sounds like your shop is not kept at a steady temperature and relative humidity and bridges will not stay on in those circumstances reliably. Music stores have to maintain proper RH and temp too or this happens to their wares as well. I remember when the music store that we ghost repaired for many years ago decided to save money and kill the AC and dehumidification in the summer over long weekends. They came in on a Monday morning and several of the stringed, ethnic instruments on the wall had lost bridges.

I'm not a fan of rub joints with any glue for bridges under string tension and would clamp a bridge every time. If the design does not allow for that it's an unserviceable design if the bridge lifts and you have to repair it.

Yes you can hear when they let loose. We have a client who was watching a football game in his living room with his brand new Rickenbacker 12 string his pride and joy on a stand right next to the TV. The bridge let loose and even suffered from metal failure right in front of him. The thing lashed around and gashed up his furniture pretty severely.

He goes on line and googles Rickenbacker tail piece failure and finds out this is common and so common in fact that Rickenbacker offers a replacement program after you jump through your own sphincter to prove you are the original owner you are granted the right to pay big bucks for a replacement. He was pissed....

Just saw one more comment where Bob says vacuum clamping is faster and easier than using clamps. I beg to differ. We preposition clamps and cauls and have methods to do so and can have everything snugged down in seconds AND we can apply much more clamping pressure per square inch which results in a superior bond.

If we thought that vacuum clamping improved our game we would have been doing it years ago. We have a substantial investment in vacuum pumps and use vacuum clamping already for our saddle mills and other jigs.