fiddler135 - Posted - 12/28/2022:  15:05:46

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

Brian Wood - Posted - 12/28/2022:  15:13:36

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

Why not make both edges straight? Anyway, that's what I do.

fiddler135 - Posted - 12/28/2022:  15:29:39

quote:

---

Originally posted by Brian Wood

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

Why not make both edges straight? Anyway, that's what I do.

---

Because it is nearly impossible make the edges perfectly flat and get a seamless joint. But you can get a seamless joint by putting a relief in the middle and let the glue pull the parts together.  

The Violin Beautiful - Posted - 12/28/2022:  17:10:17

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

I put very little in (less than .5 mm). Once the edges have been planed flat, I make a few passes to put just a small enough amount of relief in so that a straight edge laid along the length of the glue edge will just begin to show light underneath. It's important for the glue to be a good consistency--not too thick, but not watery. This way the rub joint doesn't get slimy or distorted by the glue itself. 

fiddler135 - Posted - 12/29/2022:  04:57:38

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

I put very little in (less than .5 mm). Once the edges have been planed flat, I make a few passes to put just a small enough amount of relief in so that a straight edge laid along the length of the glue edge will just begin to show light underneath. It's important for the glue to be a good consistency--not too thick, but not watery. This way the rub joint doesn't get slimy or distorted by the glue itself. 

---

Slimy? 

The Violin Beautiful - Posted - 12/29/2022:  06:58:26

quote:

Slimy? 

---

When the glue is too thick, the rub joint won't work well, and instead of feeling the glue grab from friction, it'll feel like the glue is slimy--it won't be thin enough that it feels like the two pieces of wood are in proper contact, and they will slide against each other instead of bonding quickly.

The same goes for attaching fingerboards. When the glue is too thick, they'll slip and slide around and can end up in a different position by the time the clamps come off.

It's important to check the glue before  using it. At a shop where I worked previously, we had a communal glue pot. We used good glue and always prepared it well, but with all the people using it, someone would always end up forgetting to put the lid back on the jar and it would thicken too much. Then, when it was time to put a fingerboard on, the glue would not be in good shape. Eventually, a few of us just got our own glue pots so we could always have our glue in good shape. 

fiddler135 - Posted - 12/29/2022:  15:02:35

quote:

---

Originally posted by The Violin Beautiful

quote:

Slimy? 

---

When the glue is too thick, the rub joint won't work well, and instead of feeling the glue grab from friction, it'll feel like the glue is slimy--it won't be thin enough that it feels like the two pieces of wood are in proper contact, and they will slide against each other instead of bonding quickly.

The same goes for attaching fingerboards. When the glue is too thick, they'll slip and slide around and can end up in a different position by the time the clamps come off.

It's important to check the glue before  using it. At a shop where I worked previously, we had a communal glue pot. We used good glue and always prepared it well, but with all the people using it, someone would always end up forgetting to put the lid back on the jar and it would thicken too much. Then, when it was time to put a fingerboard on, the glue would not be in good shape. Eventually, a few of us just got our own glue pots so we could always have our glue in good shape. 

---

Do you use a French fry warmer or similar device to warm the plates before applying the glue (with a rub joint)?

Edited by - fiddler135 on 12/29/2022 15:02:57

The Violin Beautiful - Posted - 12/29/2022:  23:54:22

quote:

---

Originally posted by fiddler135 Do you use a French fry warmer or similar device to warm the plates before applying the glue (with a rub joint)?

---

I've used a hair dryer or a heat gun to heat the glue surfaces before, but I've also done it without heating. Ultimately, the strength of the glue and its bond and the fit of the pieces make the biggest difference.

If you're trying to extend the working time of the glue as you join the pieces, you can alternatively do this by using slow tack glue or by working in a high heat and humidity environment, such as a sauna. I haven't felt the need to do this, but I know some people do so. 

Edited by - The Violin Beautiful on 12/29/2022 23:55:34

fiddler135 - Posted - 12/30/2022:  06:19:48

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135 Do you use a French fry warmer or similar device to warm the plates before applying the glue (with a rub joint)?

---

I've used a hair dryer or a heat gun to heat the glue surfaces before, but I've also done it without heating. Ultimately, the strength of the glue and its bond and the fit of the pieces make the biggest difference.

If you're trying to extend the working time of the glue as you join the pieces, you can alternatively do this by using slow tack glue or by working in a high heat and humidity environment, such as a sauna. I haven't felt the need to do this, but I know some people do so. 

---

I only join plates once (2 times) per violin, so I have to relearn how to do this each time, mostly by trial and error. I have also just resurfaced my plane. Anyway, do you apply glue sparingly, to prevent having excessive glue and not reaching wood to wood, or do you slop it on and squeegee the excess glue out? (I can imagine having a lot of glue on there would keep the glue above gel temperature longer.) 

fiddler135 - Posted - 12/30/2022:  06:41:51

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135 Do you use a French fry warmer or similar device to warm the plates before applying the glue (with a rub joint)?

---

I've used a hair dryer or a heat gun to heat the glue surfaces before, but I've also done it without heating. Ultimately, the strength of the glue and its bond and the fit of the pieces make the biggest difference.

If you're trying to extend the working time of the glue as you join the pieces, you can alternatively do this by using slow tack glue or by working in a high heat and humidity environment, such as a sauna. I haven't felt the need to do this, but I know some people do so. 

---

I only join plates once (2 times) per violin, so I have to relearn how to do this each time, mostly by trial and error. I have also just resurfaced my plane. Anyway, do you apply glue sparingly, to prevent having excessive glue and not reaching wood to wood, or do you slop it on and squeegee the excess glue out? (I can imagine having a lot of glue on there would keep the glue above gel temperature longer.) 

Also; is it necessary to  size the parts in order for a rub joint to work?

fiddler135 - Posted - 12/30/2022:  08:51:55

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135 Do you use a French fry warmer or similar device to warm the plates before applying the glue (with a rub joint)?

---

I've used a hair dryer or a heat gun to heat the glue surfaces before, but I've also done it without heating. Ultimately, the strength of the glue and its bond and the fit of the pieces make the biggest difference.

If you're trying to extend the working time of the glue as you join the pieces, you can alternatively do this by using slow tack glue or by working in a high heat and humidity environment, such as a sauna. I haven't felt the need to do this, but I know some people do so. 

---

I only join plates once (2 times) per violin, so I have to relearn how to do this each time, mostly by trial and error. I have also just resurfaced my plane. Anyway, do you apply glue sparingly, to prevent having excessive glue and not reaching wood to wood, or do you slop it on and squeegee the excess glue out? (I can imagine having a lot of glue on there would keep the glue above gel temperature longer.) 

Also; is it necessary to  size the parts in order for a rub joint to work?

---

I tried to edit my last post and couldn't, but anyway; I have finished the joint again, no sizing, warmer brush, less squeegee. I have been told that sizing is not necessary for a rub joint, in general anyway, but it may be for violin plates? Comments anyone?

correction; the plates WERE sized this time. There was glue in the wood from the last gluing attempt, (and replaned of course). 

---

Edited by - fiddler135 on 12/30/2022 09:09:54

The Violin Beautiful - Posted - 12/30/2022:  10:43:06

Sizing is not absolutely necessary for joining a center seam, but it’s not a bad idea, either.

When I’m joining, I’ll brush glue on the gluing surfaces, then rub it in with a finger, then wipe off excess with a paper towel. I do this on the neck when putting a fingerboard on as well. The idea behind sizing is to minimize the amount of glue getting absorbed by open pores and thereby starving the glue joint. This is more of an issue with end grain, where quite a lot of glue will be drawn in through capillary action.

I apply glue liberally to a center seam—the rubbing of the pieces together will squeeze out most of the excess, and clamping will expel the rest.

KCFiddles - Posted - 12/30/2022:  11:18:30

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

What would be the reason for putting relief into a center seam? You do understand that hide glue has virtually NO gap filling abilities, don't you? A good glue line thickness is on the order of .001- .002", and any additional gap will only weaken the joint and cause future problems. Hide glue has tremendous adhesive strength, for example its ability to form glue chips in glass, but it doesn't bridge gaps, and AFAIK it won't pull gappy joints together at all.

fiddler135 - Posted - 12/30/2022:  13:18:42

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

What would be the reason for putting relief into a center seam? You do understand that hide glue has virtually NO gap filling abilities, don't you? A good glue line thickness is on the order of .001- .002", and any additional gap will only weaken the joint and cause future problems. Hide glue has tremendous adhesive strength, for example its ability to form glue chips in glass, but it doesn't bridge gaps, and AFAIK it won't pull gappy joints together at all.

---

There are a lot of luthiers who disagree with you. In fact, Hide glue does pull the joint together as it dries and shrinks. 

fiddler135 - Posted - 12/30/2022:  14:07:06

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

What would be the reason for putting relief into a center seam? You do understand that hide glue has virtually NO gap filling abilities, don't you? A good glue line thickness is on the order of .001- .002", and any additional gap will only weaken the joint and cause future problems. Hide glue has tremendous adhesive strength, for example its ability to form glue chips in glass, but it doesn't bridge gaps, and AFAIK it won't pull gappy joints together at all.

---

What is AFAIK?

Brian Wood - Posted - 12/30/2022:  14:30:36

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

What would be the reason for putting relief into a center seam? You do understand that hide glue has virtually NO gap filling abilities, don't you? A good glue line thickness is on the order of .001- .002", and any additional gap will only weaken the joint and cause future problems. Hide glue has tremendous adhesive strength, for example its ability to form glue chips in glass, but it doesn't bridge gaps, and AFAIK it won't pull gappy joints together at all.

---

 

What is AFAIK?  Probably "As far as I know" I agree with KC it isn't necessary to spring the joint. For me dead straight is easier to achieve than an evenly tapering joint. If you do that however it should work as well as long as your relief arc is very slight and dead accurate so there will be no voids. At least AFAIK.

Edited by - Brian Wood on 12/30/2022 14:35:18

The Violin Beautiful - Posted - 12/30/2022:  16:40:03

Planing a very small relief into the plate halves is something done by a lot of excellent makers and has been taught traditionally in Cremona, Mittenwald, and Vienna, just to name a few examples.



I agree that this method is not absolutely essential, but I do find it worthwhile in my own making. I should add that the purpose of doing this is NOT to fill a gap with glue. Wood can change shape when any moisture is added, which is why it's important to check the glue surfaces after sizing--a previously flat surface can become convex with the addition of glue.

Edited by - The Violin Beautiful on 12/30/2022 16:43:47

fiddler135 - Posted - 12/30/2022:  16:48:03

quote:

---

Originally posted by Brian Wood

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

What would be the reason for putting relief into a center seam? You do understand that hide glue has virtually NO gap filling abilities, don't you? A good glue line thickness is on the order of .001- .002", and any additional gap will only weaken the joint and cause future problems. Hide glue has tremendous adhesive strength, for example its ability to form glue chips in glass, but it doesn't bridge gaps, and AFAIK it won't pull gappy joints together at all.

---

 

 

What is AFAIK?  Probably "As far as I know" I agree with KC it isn't necessary to spring the joint. For me dead straight is easier to achieve than an evenly tapering joint. If you do that however it should work as well as long as your relief arc is very slight and dead accurate so there will be no voids. At least AFAIK.

---

---

The joint I have now is passable, nearly seamless. And unless the joint closes overnight then it will prove you are right. If it does close then I will know that  a good relief is 1/2 to 1 shaving thickness. (A shaving thickness is .004 inches or 100 microns) The joint has closed some between 5 and 8 hours of drying. (I was impatient and began flattening the bottom surface at 5 hours, so the two plates are flush, and it is easy to judge the joint. I also figured if the joint failed from flattening stresses it was no good and I would rather redo it sooner as later.)  

KCFiddles - Posted - 12/30/2022:  16:51:31

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.

I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

fiddler135 - Posted - 12/31/2022:  05:13:53

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

The Violin Beautiful - Posted - 12/31/2022:  07:42:44

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”

richardjonesfurniture.com/Arti...-ups.html

KCFiddles - Posted - 12/31/2022:  09:48:07

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

---

I don't know whether you have ever seen wood fresh off a properly tuned straight-line saw, but the surface is clean and straight. Glues adhere mostly due to molecular forces, and as soon as wood is cut, it starts to react with the atmosphere, and experiments and tests show pretty clearly that fresher surfaces produce better bonds.  That was pretty important, because whether you are putting out solid wood furniture tops, oak table tops, or basses, glue joint failure is expensive, far out of proportion to what it costs to prevent it. Straight, fresh cuts were the solution.  If you're going to have cracks due to shrinkage near the ends of the boards, the cracks will not occur in the joint, but rather in the wood itself.  In fact whenever we tested glue joints to failure, the criterion of a ood joint was that the failure be in the wood and not through the glue line. 

I'm familiar with the reasoning behind sprung joints. Grew up with it, in fact. But it just doesn't hold up in real life.  A fresh cut, perfect joint clamped or rubbed, with the right amount of glue of the right consistency is going to give you the strongest joint. I prefer clamping because it prevents movement for the eight to twelve hours in which the bond is vulnerable.  Yes, hide glue does shrink as it dries, but doesn't it make more sense to have it shrink uniformly along the whole length of the joint only in parts of it? If you are worried about moisture loss from end grain, dry your wood properly, or failing that, seal the end grain better.

fiddler135 - Posted - 12/31/2022:  09:53:46

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Good discussion. If I remember correctly, I started putting a relief in the middle so that the ends would close. (That was my problem and recommended solution.) In Stradivari's day, there were professional joiners. So there's little wonder that we have a learning curve. What I get from the article is that the amount of relief should be slight, if there is one. Was this your summary also? 

KCFiddles - Posted - 12/31/2022:  10:07:42

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Mr. Jones is just another example of a person who doesn't really know what he is talking about, spreading misinformation. His explanation of glue-line creep is totally bogus and misleading, and his proposed solution is no help at all. I ran into similar problems decades ago. Has more to do with drying QC and choice of adhesives. He's also wrong about sprung joints. If his thoughts had any merit they'd be reflected in standard industrial practice.

The Violin Beautiful - Posted - 12/31/2022:  10:26:39

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Mr. Jones is just another example of a person who doesn't really know what he is talking about, spreading misinformation. His explanation of glue-line creep is totally bogus and misleading, and his proposed solution is no help at all. I ran into similar problems decades ago. Has more to do with drying QC and choice of adhesives. He's also wrong about sprung joints. If his thoughts had any merit they'd be reflected in standard industrial practice.

---

I think if you look at his bio, you'll find him to be quite the opposite of your characterization. He has taught at universities, exhibited in major galleries, and has written extensively for respected publications. 

fiddler135 - Posted - 12/31/2022:  10:40:55

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Mr. Jones is just another example of a person who doesn't really know what he is talking about, spreading misinformation. His explanation of glue-line creep is totally bogus and misleading, and his proposed solution is no help at all. I ran into similar problems decades ago. Has more to do with drying QC and choice of adhesives. He's also wrong about sprung joints. If his thoughts had any merit they'd be reflected in standard industrial practice.

---

You stated earlier that a sawn surface glue joint is stronger than a jointed surface joint. Why? 

fiddler135 - Posted - 12/31/2022:  13:09:07

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

---

I don't know whether you have ever seen wood fresh off a properly tuned straight-line saw, but the surface is clean and straight. Glues adhere mostly due to molecular forces, and as soon as wood is cut, it starts to react with the atmosphere, and experiments and tests show pretty clearly that fresher surfaces produce better bonds.  That was pretty important, because whether you are putting out solid wood furniture tops, oak table tops, or basses, glue joint failure is expensive, far out of proportion to what it costs to prevent it. Straight, fresh cuts were the solution.  If you're going to have cracks due to shrinkage near the ends of the boards, the cracks will not occur in the joint, but rather in the wood itself.  In fact whenever we tested glue joints to failure, the criterion of a ood joint was that the failure be in the wood and not through the glue line. 

I'm familiar with the reasoning behind sprung joints. Grew up with it, in fact. But it just doesn't hold up in real life.  A fresh cut, perfect joint clamped or rubbed, with the right amount of glue of the right consistency is going to give you the strongest joint. I prefer clamping because it prevents movement for the eight to twelve hours in which the bond is vulnerable.  Yes, hide glue does shrink as it dries, but doesn't it make more sense to have it shrink uniformly along the whole length of the joint only in parts of it? If you are worried about moisture loss from end grain, dry your wood properly, or failing that, seal the end grain better.

 

 

 

 

---

My question was really why are sawn surfaces more desirable (stronger when glued) than surfaces which have been dressed on a joiner? 

KCFiddles - Posted - 12/31/2022:  13:18:23

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

---

I don't know whether you have ever seen wood fresh off a properly tuned straight-line saw, but the surface is clean and straight. Glues adhere mostly due to molecular forces, and as soon as wood is cut, it starts to react with the atmosphere, and experiments and tests show pretty clearly that fresher surfaces produce better bonds.  That was pretty important, because whether you are putting out solid wood furniture tops, oak table tops, or basses, glue joint failure is expensive, far out of proportion to what it costs to prevent it. Straight, fresh cuts were the solution.  If you're going to have cracks due to shrinkage near the ends of the boards, the cracks will not occur in the joint, but rather in the wood itself.  In fact whenever we tested glue joints to failure, the criterion of a ood joint was that the failure be in the wood and not through the glue line. 

I'm familiar with the reasoning behind sprung joints. Grew up with it, in fact. But it just doesn't hold up in real life.  A fresh cut, perfect joint clamped or rubbed, with the right amount of glue of the right consistency is going to give you the strongest joint. I prefer clamping because it prevents movement for the eight to twelve hours in which the bond is vulnerable.  Yes, hide glue does shrink as it dries, but doesn't it make more sense to have it shrink uniformly along the whole length of the joint only in parts of it? If you are worried about moisture loss from end grain, dry your wood properly, or failing that, seal the end grain better.

 

 

 

 

---

My question was really why are sawn surfaces more desirable (stronger when glued) than surfaces which have been dressed on a joiner? 

---

The science of adhesives has baffled far better minds than mine and yours. I read up on it a lot when I was chasing down production problems back in the 80s, but the fact remains that the empirical studies showed that the sawn surfaces (much smoother than you might expect) had the best bond of all by a slight margin. maybe because the sawn surface had a little more "tooth", maybe because the jointed surface was rippled, or burnished. No explanation was offered that wouldn't be more than conjecture.

KCFiddles - Posted - 12/31/2022:  14:24:57

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Mr. Jones is just another example of a person who doesn't really know what he is talking about, spreading misinformation. His explanation of glue-line creep is totally bogus and misleading, and his proposed solution is no help at all. I ran into similar problems decades ago. Has more to do with drying QC and choice of adhesives. He's also wrong about sprung joints. If his thoughts had any merit they'd be reflected in standard industrial practice.

---

I think if you look at his bio, you'll find him to be quite the opposite of your characterization. He has taught at universities, exhibited in major galleries, and has written extensively for respected publications. 

---

I took some time to peruse Mr Jones's web site, and to look at some of his projects. His reproduction chairs are nice, but the rest of the work doesn't prove much. It's all artisanal and doesn't require or demonstrate any special or deep knowledge of woodworking lore. It does show some self-promotion skills, for which I take my hat off to him. Appeal to authority is one of the worst logical fallacies, and is completely invalid when looking for the truth. It's like saying "The Pope says the Earth is flat, so it must be so. Ptolemy and that Copernicus  guy must be wrong. " But if you want to argue credentials, I'll put mine against his any time. Over 60 years of professional woodworking. Millions of dollars of furniture produced and sold as owner of furniture factory started from scratch on pocket money. Consulted and assisted on major custom architectural projects. Custom finish design and execution. Years of antique furniture restoration and custom woodworking experience. Articles published on professional refinishing site. Couple of years of commercial furniture repair and touchup for Guardsman Corp. Worked for and trained by world class violin makers for years before spinning off my own fiddle business at retirement age before slowing down a bit due to health problems.  I could add more, but don't want to bore... 

Truth of the matter is that right is right and wrong is wrong, and things ought to be evaluated on their merits. I can give empirical basis from experience, not hearsay, for almost anything I write, because I hate to see people misled. Some things, like leaving a little (.001" or bare daylight) spring in a violin plate joint don't matter much, but it seems like a huge waste of time when it's pretty easy to learn how to get them straight (and not humped) in the first place. And it's worse when it shifts the focus off the more important things like basic tool skills and craftsmanship.

The Violin Beautiful - Posted - 12/31/2022:  15:47:39

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by The Violin Beautiful

Here’s an article by a professional woodworker and teacher of fine traditional furniture making that explains a lot about “sprung joints:”



richardjonesfurniture.com/Arti...-ups.html

---

Mr. Jones is just another example of a person who doesn't really know what he is talking about, spreading misinformation. His explanation of glue-line creep is totally bogus and misleading, and his proposed solution is no help at all. I ran into similar problems decades ago. Has more to do with drying QC and choice of adhesives. He's also wrong about sprung joints. If his thoughts had any merit they'd be reflected in standard industrial practice.

---

I think if you look at his bio, you'll find him to be quite the opposite of your characterization. He has taught at universities, exhibited in major galleries, and has written extensively for respected publications. 

---

I took some time to peruse Mr Jones's web site, and to look at some of his projects. His reproduction chairs are nice, but the rest of the work doesn't prove much. It's all artisanal and doesn't require or demonstrate any special or deep knowledge of woodworking lore. It does show some self-promotion skills, for which I take my hat off to him. Appeal to authority is one of the worst logical fallacies, and is completely invalid when looking for the truth. It's like saying "The Pope says the Earth is flat, so it must be so. Ptolemy and that Copernicus  guy must be wrong. " But if you want to argue credentials, I'll put mine against his any time. Over 60 years of professional woodworking. Millions of dollars of furniture produced and sold as owner of furniture factory started from scratch on pocket money. Consulted and assisted on major custom architectural projects. Custom finish design and execution. Years of antique furniture restoration and custom woodworking experience. Articles published on professional refinishing site. Couple of years of commercial furniture repair and touchup for Guardsman Corp. Worked for and trained by world class violin makers for years before spinning off my own fiddle business at retirement age before slowing down a bit due to health problems.  I could add more, but don't want to bore... 

Truth of the matter is that right is right and wrong is wrong, and things ought to be evaluated on their merits. I can give empirical basis from experience, not hearsay, for almost anything I write, because I hate to see people misled. Some things, like leaving a little (.001" or bare daylight) spring in a violin plate joint don't matter much, but it seems like a huge waste of time when it's pretty easy to learn how to get them straight (and not humped) in the first place. And it's worse when it shifts the focus off the more important things like basic tool skills and craftsmanship.

---

If the only authority to which you will appeal is your own, you stand to learn nothing. Skilled violin making, repair, and especially restoration, involve quite a lot of appeal to the authority of the great figures in the field that have come before. 

If some of the best workmen find a method useful and can point to the use of it over centuries (not hearsay or one man's opinion), that's enough authority to convince me that a method is at the very least valid.

Also, Ptolemy and Copernicus had differing models, the former a geocentric model and the latter a heliocentric one. Despite a major feature of Ptolemy's model eventually being disproven, much of the information remains useful today. Essentially both astronomers were right to a certain extent. The idea of a spherical earth had been discussed by philosophers for hundreds of years. The controversy with the Church was not about a flat earth, but  whether it was in a fixed position, and the astronomer who was brought before the Church and asked to recant his support of Copernicus was Galileo.

Edited by - The Violin Beautiful on 12/31/2022 15:58:56

fiddler135 - Posted - 01/01/2023:  05:04:01

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

---

I don't know whether you have ever seen wood fresh off a properly tuned straight-line saw, but the surface is clean and straight. Glues adhere mostly due to molecular forces, and as soon as wood is cut, it starts to react with the atmosphere, and experiments and tests show pretty clearly that fresher surfaces produce better bonds.  That was pretty important, because whether you are putting out solid wood furniture tops, oak table tops, or basses, glue joint failure is expensive, far out of proportion to what it costs to prevent it. Straight, fresh cuts were the solution.  If you're going to have cracks due to shrinkage near the ends of the boards, the cracks will not occur in the joint, but rather in the wood itself.  In fact whenever we tested glue joints to failure, the criterion of a ood joint was that the failure be in the wood and not through the glue line. 

I'm familiar with the reasoning behind sprung joints. Grew up with it, in fact. But it just doesn't hold up in real life.  A fresh cut, perfect joint clamped or rubbed, with the right amount of glue of the right consistency is going to give you the strongest joint. I prefer clamping because it prevents movement for the eight to twelve hours in which the bond is vulnerable.  Yes, hide glue does shrink as it dries, but doesn't it make more sense to have it shrink uniformly along the whole length of the joint only in parts of it? If you are worried about moisture loss from end grain, dry your wood properly, or failing that, seal the end grain better.

 

 

 

 

---

My question was really why are sawn surfaces more desirable (stronger when glued) than surfaces which have been dressed on a joiner? 

---

The science of adhesives has baffled far better minds than mine and yours. I read up on it a lot when I was chasing down production problems back in the 80s, but the fact remains that the empirical studies showed that the sawn surfaces (much smoother than you might expect) had the best bond of all by a slight margin. maybe because the sawn surface had a little more "tooth", maybe because the jointed surface was rippled, or burnished. No explanation was offered that wouldn't be more than conjecture.

---

I thought we must be talking about 2 different things. I use a wooden joiner (with single fixed blade). It doesn't produce a rippled surface. 

fiddler135 - Posted - 01/01/2023:  05:50:06

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by KCFiddles

AFAIK stands for "As far as I know". I worked for several years for the only shop in the America that makes violins, violas, cellos and basses from scratch. I think it's the only shop that has done basses for an entire national symphony section in one contract. When you are gluing up plates for basses that cost bucket loads of money, you kinda want your center seams to hold. The only way to do this is if the wood's moisture content is correct, and the joint must fit perfectly without any pressure. There is simply no rational reason for planing relief into a joint that anyone has ever shown to me. I've seen the idea presented, but never a good reason for it backed by any kind of data.



I ran a small furniture factory for about 20 years, bought glue by the barrel, and consulted directly with glue manufacturers and even had glues custom formulated. Nobody ever recommended any relief in a glue joint. We also did quite a bit of testing. The strongest joints were with a fresh cut directly off a straight-line rip saw. Second was fresh off a jointer or plane. Ageing or any other treatment only served to weaken a joint.

---

Why does a sawn surface give you a stronger joint?

---

I don't know whether you have ever seen wood fresh off a properly tuned straight-line saw, but the surface is clean and straight. Glues adhere mostly due to molecular forces, and as soon as wood is cut, it starts to react with the atmosphere, and experiments and tests show pretty clearly that fresher surfaces produce better bonds.  That was pretty important, because whether you are putting out solid wood furniture tops, oak table tops, or basses, glue joint failure is expensive, far out of proportion to what it costs to prevent it. Straight, fresh cuts were the solution.  If you're going to have cracks due to shrinkage near the ends of the boards, the cracks will not occur in the joint, but rather in the wood itself.  In fact whenever we tested glue joints to failure, the criterion of a ood joint was that the failure be in the wood and not through the glue line. 

I'm familiar with the reasoning behind sprung joints. Grew up with it, in fact. But it just doesn't hold up in real life.  A fresh cut, perfect joint clamped or rubbed, with the right amount of glue of the right consistency is going to give you the strongest joint. I prefer clamping because it prevents movement for the eight to twelve hours in which the bond is vulnerable.  Yes, hide glue does shrink as it dries, but doesn't it make more sense to have it shrink uniformly along the whole length of the joint only in parts of it? If you are worried about moisture loss from end grain, dry your wood properly, or failing that, seal the end grain better.

 

 

 

 

---

My question was really why are sawn surfaces more desirable (stronger when glued) than surfaces which have been dressed on a joiner? 

---

The science of adhesives has baffled far better minds than mine and yours. I read up on it a lot when I was chasing down production problems back in the 80s, but the fact remains that the empirical studies showed that the sawn surfaces (much smoother than you might expect) had the best bond of all by a slight margin. maybe because the sawn surface had a little more "tooth", maybe because the jointed surface was rippled, or burnished. No explanation was offered that wouldn't be more than conjecture.

---

I thought we must be talking about 2 different things. I use a wooden joiner (with single fixed blade). It doesn't produce a rippled surface. 

---

I meant "wooden jointer"  (not joiner) . I couldn't edit my post after I looked it up.

fiddler135 - Posted - 01/01/2023:  10:33:34

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

I put very little in (less than .5 mm). Once the edges have been planed flat, I make a few passes to put just a small enough amount of relief in so that a straight edge laid along the length of the glue edge will just begin to show light underneath. It's important for the glue to be a good consistency--not too thick, but not watery. This way the rub joint doesn't get slimy or distorted by the glue itself. 

---

Slimy? 

I didn't (and couldn't) measure the relief in the center of the two maple plates I glued together, but it was less than .006 inches, my thinnest feeler gauge. This is less than your recommendation of 0.5 mm, or 0.020 inches. I did a rub joint with hide glue no clamping. 

The results were I have a very tight joint, that looks to be tighter (more seamless) on each end. This could be because the ends were in contact initially, or because the center had a few thousandths to pull together and compressed the joint at the ends. 

Next time I think I will try a joint with no relief and see how it does. 

The Violin Beautiful - Posted - 01/01/2023:  10:49:44

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

I put very little in (less than .5 mm). Once the edges have been planed flat, I make a few passes to put just a small enough amount of relief in so that a straight edge laid along the length of the glue edge will just begin to show light underneath. It's important for the glue to be a good consistency--not too thick, but not watery. This way the rub joint doesn't get slimy or distorted by the glue itself. 

---

Slimy? 

I didn't (and couldn't) measure the relief in the center of the two maple plates I glued together, but it was less than .006 inches, my thinnest feeler gauge. This is less than your recommendation of 0.5 mm, or 0.020 inches. I did a rub joint with hide glue no clamping. 

The results were I have a very tight joint, that looks to be tighter (more seamless) on each end. This could be because the ends were in contact initially, or because the center had a few thousandths to pull together and compressed the joint at the ends. 

Next time I think I will try a joint with no relief and see how it does. 

---

My recommendation wasn't 0.5 mm, but just enough relief for light to show under a straight edge, LESS THAN 0.5.

fiddler135 - Posted - 01/01/2023:  12:43:42

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by fiddler135

quote:

---

Originally posted by The Violin Beautiful

quote:

---

Originally posted by fiddler135

How much relief do you put in the center seam of a violin plate, when doing a rub joint? That is, what is the maximum gap for the (hide) glue to pull together?

---

I put very little in (less than .5 mm). Once the edges have been planed flat, I make a few passes to put just a small enough amount of relief in so that a straight edge laid along the length of the glue edge will just begin to show light underneath. It's important for the glue to be a good consistency--not too thick, but not watery. This way the rub joint doesn't get slimy or distorted by the glue itself. 

---

Slimy? 

I didn't (and couldn't) measure the relief in the center of the two maple plates I glued together, but it was less than .006 inches, my thinnest feeler gauge. This is less than your recommendation of 0.5 mm, or 0.020 inches. I did a rub joint with hide glue no clamping. 

The results were I have a very tight joint, that looks to be tighter (more seamless) on each end. This could be because the ends were in contact initially, or because the center had a few thousandths to pull together and compressed the joint at the ends. 

Next time I think I will try a joint with no relief and see how it does. 

---

My recommendation wasn't 0.5 mm, but just enough relief for light to show under a straight edge, LESS THAN 0.5.

---

I reread your post. You do clearly say less than 0.5 mm.  So I was about right . Thank you.

Edited by - fiddler135 on 01/01/2023 12:44:48