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-   -   Maple binding gap (https://www.acousticguitarforum.com/forums/showthread.php?t=631896)

Bruce Sexauer 11-24-2021 11:20 AM

Aliphatic glue, which is the most common glue for wooden bindings, requires 150 lb per square inch of clamping pressure to achieve its bonding potential, according the Franklin Industries, the maker of Titebond. Masking tape doesn’t come close to being able to do that, and the joins made by tape clamping are what I call “proximity joins”, where the glue holds the pieces near each other, but not actually bonded together. This can look okay, but a guitar relies on the integrity of its joinery to approach its tonal potential, and every part counts in the final tally.

Plastic bindings, as I glue them, are another kettle of fish. They are attached with solvent based adhesives and literally melt into their ledges, making close proximity good enough for the task.

If anyone wants to discredit my understanding of lutherie, they are welcome to educate me, but please bring your facts to the table.

IndianHillMike 11-24-2021 12:05 PM

I think there are many ways to successfully do a job so I'm not attempting to discredit anyone, but in defense of tape (which is all I've ever used with no problems) I think it's more than adequate for applying/holding enough pressure. With 3/4" tape and a 1/4" of binding height, that's an area of .1875 sq. in.. In theory that means you only need ~28 lbs. of pressure to get the maximum bonding with aliphatic glues per piece of tape. I apply that pressure with my hand and stretch the tape tight over the joint so the tape only has to hold that pressure but not actually apply it. I also round over the outside corner of my binding strips to prevent the tape from ripping and will double up layers of tape in the waist to really reef on it.

I think rope is a great way to bind but I also think tape (done properly) can be just as good.

Shuksan 11-24-2021 01:01 PM

Quote:

Originally Posted by Bruce Sexauer (Post 6863543)
Aliphatic glue, which is the most common glue for wooden bindings, requires 150 lb per square inch of clamping pressure to achieve its bonding potential, according the Franklin Industries, the maker of Titebond. Masking tape doesn’t come close to being able to do that, and the joins made by tape clamping are what I call “proximity joins”, where the glue holds the pieces near each other, but not actually bonded together. This can look okay, but a guitar relies on the integrity of its joinery to approach its tonal potential, and every part counts in the final tally.

Plastic bindings, as I glue them, are another kettle of fish. They are attached with solvent based adhesives and literally melt into their ledges, making close proximity good enough for the task.

If anyone wants to discredit my understanding of lutherie, they are welcome to educate me, but please bring your facts to the table.

Since we are talking facts, how many pounds per square inch does roping the binding bring to bear and how did you measure it?

You claimed that binding tape is "incapable of controlling the fit in the channel" (referring to wood bindings). I get excellent fit of wood bindings using binding tape. I know other builders who also get excellent fit using binding tape. And, for everyone of those builders that I know, there are many more who do too. If you like using rope, great, but don't dis other methods that work just because they aren't your personal favored method. .

Are you actually claiming that clamping binding with rope has an audible positive effect on the tone of the guitar compared to clamping with binding tape?

Bruce Sexauer 11-24-2021 03:35 PM

Quote:

Originally Posted by Shuksan (Post 6863613)
Are you actually claiming that clamping binding with rope has an audible positive effect on the tone of the guitar compared to clamping with binding tape?

Yes, I do actually think this is true.

dnf777 11-24-2021 04:20 PM

Fit is important.
Prep is important.
Clamping is important. (Tape, rope, rubber strip, etc)
Adhesive choice is important.

Why debate relative importance? Optimize each factor to get the best result.

I run a StewMac square file around the channel to square it up (and rough it up a bit) then run a naptha-moist rag to clean out all sawdust. I have used both aliphatic and SM binding glue with maple, with excellent, durable results.

Remember the simple physics that says ‘any force applied to make the binding fit, must be subtracted from whatever binding/clamping force you apply’. Thats why I pre-bend and try to get a near complimentary fit. So ALL the clamping force goes into the bond, and not overcoming gaps.

(And I sell my guitars for $1 million apiece…I just havent sold any yet!). :D

redir 11-24-2021 07:24 PM

From my personal experience going on 70 guitars now I find there are two kinds of bindings. Ones that are thick enough to cut through the sides into the kerf linings and ones that don't, they are the same thickness of the sides. If you cut through the sides to the linings then you will notice a difference in tone when the bindings are complete. This is why if I use celluloid I make sure NOT to go deeper than the sides into the linings. Wood bindings become a part of the instrument imho.

Neil K Walk 11-26-2021 02:18 PM

I had the same problem when my homemade binding channel cutting jig didn’t true up against the sides so that the channels weren’t square or uniform depth. I had to clean up the channels with files and rasps. I also had to get creative with extra purfling and dust mixed with thin CA glue.

Simon Fay 11-26-2021 03:40 PM

I would respectfully disagree with Bruce on this matter. I also use rope but now do a mix of both roping and taping. As long as you are using a glue that dries really hard and don't have any gaps, then structurally - the additional clamping pressure of rope shouldn't matter much, IMO. FYI, I use filament tape and apply quite a bit of pressure. I've also tested rubbed and then tapped Titebond joints and they are quite strong and structurally sound. If it does impact tone, I sincerely believe it would be so insignificant and not worth focusing on in the grand scheme of things. I recommend using the method that gives you the best results for how you build. The goal with binding is to have a perfectly seamless binding/purfling with absolutely no gaps - and both roping and taping can provide those results. We all have different methods that seem to work best for us and like Bruce, I do like to employ rope as much as I can.

Back to the OP question. I have a 15' back radius and a 1" drop in height from the tailblock to the headblock. This absolutely creates a problem with ebony binding (my default wood).

**The solution is to create a bending form that duplicates the curve of the back. So take some poster paper and trace along the side/back joint and mark the waist centerline. I then transfer this to a spare side material, cut it out on the bandsaw, and then tape my bindings to it. Some builders will cut their sides before bending but I do it afterwards. If you do it afterwards like me, then you will need to create a special bending form as I detailed above.

This will create the necessary curves around the waist and upper bout that are giving you so much trouble. I make my bending forms from neck blanks offcuts. You will have a left side and a right side and I build in batches of two - so there are 4 pieces of binding that get taped to this form. If you have questions, feel free to give me a call (email me first as I never answer unknown calls anymore, number is on bottom of my website).


FYI, regarding the kind of tape and rope to use:

Rope -- I prefer to use 1/4" braided cotton rope. Make sure it is the kind that will stretch as some rope is formed around a core and is not very stretchable. There is an art to roping guitar binding - I believe there are some videos on YouTube.

Tape - I use the 3M Scotch 433 masking tape for attaching my binding to the special bending slat. And Scotch 897 Filament tape for taping the binding to the guitar.

JboneCapo 11-28-2021 05:00 PM

Thanks everyone for your input.
I managed to get my bindings on yesterday , not perfect but alot better than they first were

To cut the bindings I used a palm router, I used a tilting bed to square up the channel. Cutting from the upper bout to neck and blended the difference (Robert O'brien YouTube)

I got them as close as I could with a bending iron and tried to give it the compound bend but there still was a little gap.
I then used an iron with a little water to press them in which helped a little.

I used 3m fiberglass tape when gluing and some old braided rope i used for petrol motor pull chords to tighten it all up. (Something stretchy wider and softer next time as it dug in a little)

Probably not the best way of going about it I'm sure but it got me there..

I'll definitely be using the method Simon suggested on the next one , great idea!

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