Glue joint test

qbilder

slower than snails
Silver Member
They note at the end of the article that most of the joints were at least partial wood failure, meaning all of the glues bonded stronger than the wood itself. IMO, the test showed the weakest pieces of wood as much as it compared the glues, hence contaminating the test & making the results questionable. While a neat test & makes for an interesting magazine article, I don't put much faith in it. The test also relied on breaking the bond of an open mortise joint at 45 deg. That's akin to testing an "A" joint by using lateral force on the cue. IMO, the test doesn't really tell me a whole lot about which glues work best in a cue.
 

conetip

AzB Silver Member
Silver Member
This test was not the same or similar to what cues experience.

Cyclic fatigue and resonance. The glue and the construction really do need to be able to withstand both. So the compromise comes as the strongest glue may not be able to withstand the cyclic fatigue, or the resonance itself may make the glue fail prematurely.
These issues are not just faced with cuemakers , but club makers etc etc.
 

DMM4342

AzB Silver Member
Silver Member
Note that no test was done with parallel grain.
Grain was oriented 90º.
Dave
EDIT
I would like to see two other tests:
1. a parallel test
2. a scarf joint 1/8 (ratio) test
 
Last edited:

louieatienza

AzB Silver Member
Silver Member
Note that no test was done with parallel grain.
Grain was oriented 90º.
Dave
EDIT
I would like to see two other tests:
1. a parallel test
2. a scarf joint 1/8 (ratio) test

I think this is a pretty extreme test that shows the ultimate strength of the joint in a worse-case scenario. So in a best-case scenario - parallel grain, joint in shear - the results would be much higher strength, but...

1 - I think the results in a parallel test would be negligible, since the shear strength would likely be exponential with the length of the joint. The extreme cases would be the radially and flat laminated butts and shafts, and they're reinforced by butt caps, joint collars, and ferrules.

2 - The scarf joint is designed such that any compressive force is distributed, in the direction that the force is directed to. So the only strength that could possibly be measured is by pulling the joint apart, an unrealistic scenario as far as cues are concerned.

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One factor I think that matters more would be heat resistance, which PVA and some epoxies are probably not best at, like when a cue is left in a hot car. (I'm sure builders here would advise against it to their customers but they do it anyway.) Another issue would be "cold-creep", something that water-resistant PVA and some epoxies can be guilty of. Yet another would be glue hardness. Some glues may absorb (or decouple) vibrations and resonance, some glues may transfer them more. And yet another factor would be gap-filling ability. Some epoxies can fill large voids, PVA can fill some very small voids, while hot hide glue requires perfect joints (intolerant of voids).

I built a couple decent personal cues about 20 years ago when I had my cabinet shop. Right now my handiwork consists mainly of building acoustic and electric guitars. I do use manly type-I PVA glue. The best builders today insist on (fresh) hot hide glue, as it allows for the smallest possible glue line thickness for its strength, leading to (presumably) the best coupling of wood for sound transference. Now some of these joints are only 1/4" width, of softwood, glued on a bias, bracing a top only about 3/16" thickness, and withstanding about 180lbs. of string pull. The glue surface on the rim to the tops and backs are only 3/8" wide. PVA also dries very hard, and it's my main choice simply because of convenience. I do mix it up as to my needs - PVA type-I on most joints where glue up time is quick, epoxy when 1) I need extra clamp up time 2) I'm using oily woods like cocobolo 3) I don't want to introduce moisture to the joint (back seam, neck join to body), PVA type-II water resistant on parts I need to bend (and thus must introduce moisture), CA for inlays and capillary-action type gluing (some binding)...

The fact that many acoustics have survived nearly 150 years, untouched, is a testament to the strength of hot hide glue. Unfortunately it has drawbacks. It must be kept around 140deg. in a dedicated heating pot when in use. The parts, and room ideally, should be kept warm to avoid the glue from gelling and skinning over, and it does so very quickly. Being water-based does introduce the problem of moisture. There is no gap filling ability, so the joint must be 100% perfect to last. On the positive side, the fact that hot hide glue forces you to make a perfect fitting joint does ensure that what you make will be better, by virtue of better craftsmanship; it's very comforting to know that some slop or tolerance can be compensated for with epoxy (and filler). And the bond created with hot hide glue is tenacious; it will bond most anything to anything; it was once used to "etch" glass where a design was painted with hot hide glue on glass, left to cure, and chipped off, taking the smooth outer skin of the glass with it. It is also the only glue that is truly reversible, as hot steam would release the joint, and warm water will remove all traces of glue. With every other glue, it cannot be removed once absorbed by the wood, and thus wood has to be removed to re-glue, because most all other glues wont adhere to itself. In the acoustic guitar world, this usually means a devaluation of the instrument if it's of high value.
 

john coloccia

AzB Silver Member
Silver Member
Just a couple more things to add:

Hot hide glue has EXCELLENT heat resistance. Most people think it's poor, but they're thinking about moist heat...steam, for example. Stick it in an oven and you'll be very surprised how well it holds up. I generally really like hot hide glue.

Give Titebond Extend a try. It drys harder than Titebond and actually sands pretty nicely too. An old Franklin employee turned me on to it.

I think this is a pretty extreme test that shows the ultimate strength of the joint in a worse-case scenario. So in a best-case scenario - parallel grain, joint in shear - the results would be much higher strength, but...

1 - I think the results in a parallel test would be negligible, since the shear strength would likely be exponential with the length of the joint. The extreme cases would be the radially and flat laminated butts and shafts, and they're reinforced by butt caps, joint collars, and ferrules.

2 - The scarf joint is designed such that any compressive force is distributed, in the direction that the force is directed to. So the only strength that could possibly be measured is by pulling the joint apart, an unrealistic scenario as far as cues are concerned.

-----------------------------------------------------------------------------------------------------------

One factor I think that matters more would be heat resistance, which PVA and some epoxies are probably not best at, like when a cue is left in a hot car. (I'm sure builders here would advise against it to their customers but they do it anyway.) Another issue would be "cold-creep", something that water-resistant PVA and some epoxies can be guilty of. Yet another would be glue hardness. Some glues may absorb (or decouple) vibrations and resonance, some glues may transfer them more. And yet another factor would be gap-filling ability. Some epoxies can fill large voids, PVA can fill some very small voids, while hot hide glue requires perfect joints (intolerant of voids).

I built a couple decent personal cues about 20 years ago when I had my cabinet shop. Right now my handiwork consists mainly of building acoustic and electric guitars. I do use manly type-I PVA glue. The best builders today insist on (fresh) hot hide glue, as it allows for the smallest possible glue line thickness for its strength, leading to (presumably) the best coupling of wood for sound transference. Now some of these joints are only 1/4" width, of softwood, glued on a bias, bracing a top only about 3/16" thickness, and withstanding about 180lbs. of string pull. The glue surface on the rim to the tops and backs are only 3/8" wide. PVA also dries very hard, and it's my main choice simply because of convenience. I do mix it up as to my needs - PVA type-I on most joints where glue up time is quick, epoxy when 1) I need extra clamp up time 2) I'm using oily woods like cocobolo 3) I don't want to introduce moisture to the joint (back seam, neck join to body), PVA type-II water resistant on parts I need to bend (and thus must introduce moisture), CA for inlays and capillary-action type gluing (some binding)...

The fact that many acoustics have survived nearly 150 years, untouched, is a testament to the strength of hot hide glue. Unfortunately it has drawbacks. It must be kept around 140deg. in a dedicated heating pot when in use. The parts, and room ideally, should be kept warm to avoid the glue from gelling and skinning over, and it does so very quickly. Being water-based does introduce the problem of moisture. There is no gap filling ability, so the joint must be 100% perfect to last. On the positive side, the fact that hot hide glue forces you to make a perfect fitting joint does ensure that what you make will be better, by virtue of better craftsmanship; it's very comforting to know that some slop or tolerance can be compensated for with epoxy (and filler). And the bond created with hot hide glue is tenacious; it will bond most anything to anything; it was once used to "etch" glass where a design was painted with hot hide glue on glass, left to cure, and chipped off, taking the smooth outer skin of the glass with it. It is also the only glue that is truly reversible, as hot steam would release the joint, and warm water will remove all traces of glue. With every other glue, it cannot be removed once absorbed by the wood, and thus wood has to be removed to re-glue, because most all other glues wont adhere to itself. In the acoustic guitar world, this usually means a devaluation of the instrument if it's of high value.
 

louieatienza

AzB Silver Member
Silver Member
Just a couple more things to add:

Hot hide glue has EXCELLENT heat resistance. Most people think it's poor, but they're thinking about moist heat...steam, for example. Stick it in an oven and you'll be very surprised how well it holds up. I generally really like hot hide glue.

Give Titebond Extend a try. It drys harder than Titebond and actually sands pretty nicely too. An old Franklin employee turned me on to it.

John, thanks... the best guitar builders use HHG for bridge and fretboard gluing, and that's one main reason.

This TiteBond Extend seems just the ticket when I do my side laminations and bracings, and bindings, where I could use more set-up time than TiteBond I.....
 

DMM4342

AzB Silver Member
Silver Member
I think this is a pretty extreme test that shows the ultimate strength of the joint in a worse-case scenario.

PARALLEL GRAIN JOINTS'
As or parallel grain it is the easiest to glue. So my reason for that test stands. If that test fails there would be no need to do any further tests.

SCARF JOINTS;
Sneaky Petes have scarf joints with varying ratios. So my reason for scarf test stands.

I did not include the worse case scenario. That would be end-grain to end-grain. An example of end-grain to end-grain is when cue makers adhere rings (sliced from cylinders) to the end-grain of shafts, forearms, handles and butts.

Dave
 

louieatienza

AzB Silver Member
Silver Member
PARALLEL GRAIN JOINTS'
As or parallel grain it is the easiest to glue. So my reason for that test stands. If that test fails there would be no need to do any further tests.

SCARF JOINTS;
Sneaky Petes have scarf joints with varying ratios. So my reason for scarf test stands.

I did not include the worse case scenario. That would be end-grain to end-grain. An example of end-grain to end-grain is when cue makers adhere rings (sliced from cylinders) to the end-grain of shafts, forearms, handles and butts.

Dave

In case 1the only potential for joint failure is excessive moisture, otherwise the wood will fail before the glue ever does, as in the 90 degree test. A similar thing happens with the splice which is as close to parallel grain as possible. You see in the lathe mishap in another thread that the glue held up fine, but the wood did not. Your reasoning is actually opposite to what's true - if the wood fails before the glue in a 90 degree joint, which is cross grain, then the wood will fail parallel grain where the grain "strength" is greater.

The absolute worst case scenario would be end grain to end grain, though cue makers do not rely on that solely, which is why butt caps and joint sleeves are threaded, as well as forearms to handles and handles to butts and ferrules to shafts.
 

JC

Coos Cues
I'm not even a tiny bit surprised. His findings pretty much mirror my own tests through the years. Every time I hear people knock cyano glues, I giggle to myself like Monalisa.

The only caveat I see is longevity and he did mention that he hadn't gathered enough data to draw conclusions.

You on the other hand probably have.

JC
 

qbilder

slower than snails
Silver Member
The only caveat I see is longevity and he did mention that he hadn't gathered enough data to draw conclusions.

You on the other hand probably have.

JC

No long term issues that I know of thus far. The jury is still out but it's been long enough that I am comfortable using it ANYWHERE in a cue. That said, it's not the best option for every application. There are a few places I won't use it for one reason or another, but none of those reasons are a lack of strength or durability.
 

qbilder

slower than snails
Silver Member
Take that test with a grain of salt.
Nothing has beat West System when done right in my own tests.
It's not brush and clamp right away process.

I take it for what it showed, which is a guy testing all the glues exactly the same way & letting the chips fall where they may. While he did have some preconceived notions, he never let bias sway his perception of the results. He was admittedly surprised and amazed.

That said, he didn't say whether he allowed for ample wet-out or not with the slow hardener. I suspect he didn't, and that's why he found the fast hardener to be better. However, I don't think it would have made much difference. It would have maybe made the slow better than the fast, but still middle of the pack in the line-up, IMO. That's the only discrepancy between his test results & my own.
 

JoeyInCali

Maker of Joey Bautista Cues
Silver Member
I take it for what it showed, which is a guy testing all the glues exactly the same way & letting the chips fall where they may. While he did have some preconceived notions, he never let bias sway his perception of the results. He was admittedly surprised and amazed.

That said, he didn't say whether he allowed for ample wet-out or not with the slow hardener. I suspect he didn't, and that's why he found the fast hardener to be better. However, I don't think it would have made much difference. It would have maybe made the slow better than the fast, but still middle of the pack in the line-up, IMO. That's the only discrepancy between his test results & my own.

End grans suck epoxy like it sucks milk.
I suspect a lot of buzzing joint screws and A-joints are due to gaps developing after epoxy gets sucked in and the joinery developing gap or gaps.
I did my tests eons ago and just as TW alluded too, strength is not just the important quality . My late mentor swore by one epoxy. IT was the only one he used for collars, A-Joint and butt plates. It was the strongest epoxy I know of.
But, I don't even use it anymore as I've found ways how West beats it in every cue making purpose. The only major drawback to West System is, it take a ton of heat in case you have to blowtorch a screw. So make sure you never have to blow torch a screw. Or at least use West on collars too.

https://youtu.be/_vIszsybR4M?t=735
Another video test .
Epoxy is ridiculously strong on this one.
 

qbilder

slower than snails
Silver Member
strength is not just the important quality
Dare I say strength is not all that critical at all in many aspects of cue work. Take a typical "A" joint for example. It already has a threaded metal stud or threaded tenon providing the joint strength. It also has a tenon & bore. What's required there is an adhesive that can keep the tenon and bore from rubbing(buzzing) while also acting as a thread lock to prevent the joint from unscrewing. A hard curing glue will break and buzz. A non-hardening glue will defeat the purpose. Goldilocks is the ticket.
 
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