Truss Rod Questions (taping, Glue, And Adjusting Dual Truss Rods)

[WezV]

calm down spoke i was actually listening to your advice and asking the reasons behind it. I was being completely honest when i said this is not something i have ever been told to do. at first i thought that might be a cultural thing but sam_c is local to me and has always done things the way you suggest. I guess i missed that lesson at school, although i did embarrasingly leave school with only an E in woodwork... if its not vaguely guitar shaped i am not really interested in doing it which is why i probably watch more guitar shows and read more guitar mags than i do woodwork ones

I think you took my posts as criticism of the method when actually i just wanted to know the reasons why people do it this way. I am not afraid to admit i am still relatively inexperienced in some areas of woodwork. You may think that is me making myself look stupid, but i have always preferred to ask the question i am not sure of the answer to

like i said before - now i know there is this way of doing things i will try it

[sam_c]

Im certainly no guitar builder, or a particularly good woodworker to be honest. Ive built more furniture and misc. objects than I have guitars. Jeeez Wez, you got an E?? what did you do? set it on fire and hand it in?

I would have thought the amount of glue would make a big difference to this aswell. I tend to use waaay too much and then spend ages wiping off squeeze out and I'll leave stuff clamped up for a few days. More to do with availability of spare time than any other reason.

I would think that if you put enough glue on the one surface then starvation isnt a problem, and I normally spend a few minutes aligning the board and prepping clamps so that amount of time may be enough for the glue to soak into the second surface. Spoke may be able to correct me though if Ive missed something obvious.

[SwedishLuthier]

Re tape: I generally use it as I don’t like to "fill" the truss rod route with silicone. Why? I dunno, but I have worked a lot with Silicone and I have seen what it looks like in ten years time... Not pretty and I don’t want that in my necks. So I tape up as the SM instructions. I recently disassembled an old neck (for a neck reset, thought that I should do a complete FB removal just for practice...) and was amazed to see that I had forgotten to remove the tape. And I had used quite thick masking tape! There were no visible glue line between the FB and the neck and the joint between the FB and the neck was not the reason for the neck reset (old failed project, a resolectric were I failed while calculating the neck angle, loch time ago, been sitting in the corner ever after...). And I had only used glue on one side as I have up until now never heard about the reasons to glue both sides (not dissing you WS, Í had no idea, might try both sides in the future). The thing is that the neck hold up fine over the years (and it had been strung up ever after I realized I had screwed up...) in spite of the tape still being there. As really funny coincidence I am in the finishing state of a commissioned build and I accidentally forgot to pull the tape of on this one too! Just a few weeks after I had made the discovery on the neck I took apart. I wonder if there is tape under any more of my fretboards?

Re Polyurethane glue: I have used that to glue up several neck were I have graphite between wood (graphite-wood joints) all the way through the neck like on this one;

and I have not had any problem at all with those necks or joints. No visible glue lines and a no failing joints. I stopped using it only because it was too messy when all the drips started to foam up. So I'd say that Poly glue, used correctly can have its place in guitar building.

[Mattia]

I use poly to laminate things I don't want coming loose under heat. Like headblocks, and sometimes headplate laminates, but only if I can clamp really, really, really well. These days I actually prefer working with epoxy, however.

[SwedishLuthier]

Yeah, Epoxy is my first choise for everything "non wood" nowdays

[Muzz]

I prefer PVA to any other glue for wood because of its mechanism of action, it cross links the wood fibers together, rather than totally rely on a sandwich layer of glue between the fibers. I do spread the PVA on both sides of the join to get the glue to make good contact, but it does not need to wick in more than a few hundred micrometres if that, so spreading on both sides is probably unecessary 99 times out of a 100 but if you want to avoid Murphy's law I would still use it as insurance, to avoid stuffing up on the 100th time when it was needed.

For the tape on box truss rods, yep it is supposed to be left on as insurance against epoxy glue getting onto the threaded rod at the bottom of the neck route.

[Muzz]

And Aussies, you do not have to buy Titebond there is nothing magical about it, good old Selleys is the poo too

[Mender]

And Aussies, you do not have to buy Titebond there is nothing magical about it, good old Selleys is the poo too

That is a waterproof exterior glue, so it would be like Titebond 2. I think you would have problems trying to get dye to take on the glue lines. For guitar building, you would be much better off getting the Selleys Aquadhere Interior which will take dye.

[Muzz]

That is a waterproof exterior glue, so it would be like Titebond 2. I think you would have problems trying to get dye to take on the glue lines. For guitar building, you would be much better off getting the Selleys Aquadhere Interior which will take dye.

Hey Mender, yep that's right, this is my cupboard

But I have been following the saying, "when all else fails read the instructions" have a look at the third bullet point

As soon as Wez reads that, his exploded guitars will all magically coalesce, their joints breathing a sigh of relief as they reseal.

If you read the instructions on the big bottle of interior it even says that it is suitable for end grain joins, because Selleys knows that the myth about end grain joints is an over extrapolation from soft timber and badly cut joints. In some timbers with a well cut join, the end grain join is stronger than the side grain.

[Woodenspoke]

I like to belive I have some experience with what I choose to discuss. I didntt ask to make this a glue discussion and up end the OP but I did need to explain my posistion. If your comments were intentional or not, they were based on limited information and confusing to people who do not know what is or isnt correct. Usually when I think I have no clue I spend some time on the internet doing research or listening to whats being said before I comment.

Google book on gluing

Read Page 196

Something a bit easier

Idiots guide

I am sure If I tryed harder I would find many nore instances supporting what I said.

I liked the show me your glue shelf and will start a new thread in the shop and tools section..Great Idea

[SwedishLuthier]

As mentioned this isn’t a thread about glue, but as it has become a really interesting discussion about gluing techniques I cannot help continuing off topic…

For those who can’t bother to follow the link Woodenspoke posted, this is an excerpt from the quite interesting article: “With some adhesives, such as resorcinol, […] double spreading […] may be specified for dense woods and surfaces of low porosity to allow wetting of the wood and to permit thickening of the adhesive to prevent excessive squeeze-out.”

Unfortunately this doesn’t prove anything to me. It says that some specific glues (http://en.wikipedia.org/wiki/Resorcinol_glue, seems to be an outdoor glue that I doubt have much use in guitar building) together with dense wood (that part applies to most woods used in guitar building) benefit from being applied to both surfaces. But that isn’t a general rule. I think it’s quite funny to read what he also writes: “if all else fails, read the instructions”. That’s exactly what Muzz has done and the label on his bottle clearly states “Add adhesive liberally to one surface only”! On the other hand the instructions for original Tightbond:

http://www.titebond.com/download/pdf/ww/OriginalTB.pdf

doesn’t mention if it is supposed to go on one or both surfaces. Can’t find this topic in their knowledge data base either (got a time out when doing a serach). I have shot them an e-mail asking, just to get the manufacturers point of view on this. I’ll report back on that part if/when I get a reply.

Unfortunately this leaves us with the information that according to the writer of that article some glues for some application benefit from being applied to both surfaces. But there is at the same time a manufacturer that claims that their glue should be applied only to one surface. No conclusive data as they say in Mythbusters...

I think the most important lesson here is that you need to learn how to use the glue you use. If the information isn’t available, contact the manufacturer, explain what you are doing and ask them how their glue should be applied.

[Dave_B]

As mentioned this isn’t a thread about glue, but as it has become a really interesting discussion about gluing techniques I cannot help continuing off topic…

Well, I've tried to change the original topic for those trying to find it six months from now. Personally, I appreciate and will benefit from the discussion.

I have to say, I don't think I would purposely go against instructions that eventually lead back to the engineers and/or scientists who developed the product. But maybe I'm giving the glue makers too much credit?

[WezV]

I like to belive I have some experience with what I choose to discuss. I didntt ask to make this a glue discussion and up end the OP but I did need to explain my posistion. If your comments were intentional or not, they were based on limited information and confusing to people who do not know what is or isnt correct. Usually when I think I have no clue I spend some time on the internet doing research or listening to whats being said before I comment.

who is this directed at spoke?

[Muzz]

As mentioned this isn’t a thread about glue, but as it has become a really interesting discussion about gluing techniques I cannot help continuing off topic…

For those who can’t bother to follow the link Woodenspoke posted, this is an excerpt from the quite interesting article: “With some adhesives, such as resorcinol, […] double spreading […] may be specified for dense woods and surfaces of low porosity to allow wetting of the wood and to permit thickening of the adhesive to prevent excessive squeeze-out.”

Unfortunately this doesn’t prove anything to me. It says that some specific glues (http://en.wikipedia.org/wiki/Resorcinol_glue, seems to be an outdoor glue that I doubt have much use in guitar building) together with dense wood (that part applies to most woods used in guitar building) benefit from being applied to both surfaces. But that isn’t a general rule. I think it’s quite funny to read what he also writes: “if all else fails, read the instructions”. That’s exactly what Muzz has done and the label on his bottle clearly states “Add adhesive liberally to one surface only”! On the other hand the instructions for original Tightbond:

http://www.titebond.com/download/pdf/ww/OriginalTB.pdf

doesn’t mention if it is supposed to go on one or both surfaces. Can’t find this topic in their knowledge data base either (got a time out when doing a serach). I have shot them an e-mail asking, just to get the manufacturers point of view on this. I’ll report back on that part if/when I get a reply.

Unfortunately this leaves us with the information that according to the writer of that article some glues for some application benefit from being applied to both surfaces. But there is at the same time a manufacturer that claims that their glue should be applied only to one surface. No conclusive data as they say in Mythbusters...

I think the most important lesson here is that you need to learn how to use the glue you use. If the information isn’t available, contact the manufacturer, explain what you are doing and ask them how their glue should be applied.

Those are wise words SwedishLuhier, you are right, we do not have any conclusive evidence as yet, and evidence would need to be experiments done on joints done both ways, not just people's subjective opinions.

The concept that I think you and most PGers have got their head around is that if one technique is good and works well it does not necessarily follow that all alternate techniques are bad and wrong.

In the following pic you can see an oak table that I built, the top was rescued from a 1940's pedestal table that was falling to bits, the top was split in two and stained dark brown. Each of the legs are made of two pieces of wood PVA glued longitudinally and for them and the top, I broke the manufacturer's rule and used Aquadhere spread on both sides of the join. It is two years old and didn't explode when I read the directions that I should have only spread on one side.

What I think is a much more important issue is some bad advice out there about fitting box truss rods, Paulie and I have chatted about this before

Click Here

[SwedishLuthier]

The concept that I think you and most PGers have got their head around is that if one technique is good and works well it does not necessarily follow that all alternate techniques are bad and wrong.

You are partly right. I, like most other people, tend to stick with what have worked before and if it has worked, why alter the formula. At the same time I like to experiment. I am really tempted to try the glue application empirically: Get say twenty test pieces from the same wood type and same type of surface preparation, glue ten of them with glue on one side and ten with glue on both sides and after sufficient drying time test to see what breaks first, the one sided application, the two sided application of the wood on either side of the joint. The only thing retaining me from doing this is that my suspicion is that both joints will be stronger than the wood, so the whole issue ends up in a big nuthin. But maybe I'll get around to do those tests and if so I'll report back

And I still haven't got any reply from Franklin...

[Muzz]

The concept that I think you and most PGers have got their head around is that if one technique is good and works well it does not necessarily follow that all alternate techniques are bad and wrong.

You are partly right. I, like most other people, tend to stick with what have worked before and if it has worked, why alter the formula. At the same time I like to experiment. I am really tempted to try the glue application empirically: Get say twenty test pieces from the same wood type and same type of surface preparation, glue ten of them with glue on one side and ten with glue on both sides and after sufficient drying time test to see what breaks first, the one sided application, the two sided application of the wood on either side of the joint. The only thing retaining me from doing this is that my suspicion is that both joints will be stronger than the wood, so the whole issue ends up in a big nuthin. But maybe I'll get around to do those tests and if so I'll report back

And I still haven't got any reply from Franklin...

That is a great experiment design, good amount of repeats and properly controlled. Whatever happens it would tell us whether one technique is better or if there is no difference between the techniques.

Now my 1940's table top gave way along a glue join, if the person who made it is on the forum, please tell us whether you spread the glue down one side of the join or two, because that join was b.a.d. it only lasted 70 years Fancy not being able to support me and a couple of friends dancing on it and playing air guitar at the end of a few parties

[DC Ross]

If it sticks, it sticks. Move on...