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  1. #1

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    I use hhg for almost all of the glue joints in my instruments.
    I use hhg partially for one of its many great qualities and that is it sets up quickly. However this makes certain joints more difficult, like joining the back or top plate to the ribs. The total length of the joint between the ribs and either plate is about 70". I like to apply glue to both surfaces of the ribs and the plate (so thats 140" glue line). It takes me about 45 seconds just to put the glue on both warmed up parts if I'm using using a small brush. That leaves me 15 seconds to assemble and clamp in place the back or belly to the ribs. That can be done with ease if you and your parts are prepared.


    Assembling the parts accurately after the glue is applied is the first challenge. Anyone who has glued a plastic model airplane together has done so with the aid of locator pins. That is where one part has two or more pins and the other part has correspondent holes to recieve the pins. When the two parts are glued together, they are locked in the correct position when the pins are inserted in their correspondent holes. This is the perfect solution for accurate and speedy assembly.


    Adding locator pins to the ribs at the headblock and the tailblock is a simple process. Just drill a couple of shallow holes and glue in a small dia. hardwood dowell of the proper length in each one and you have your pins. Then to locate the correspondent holes coat the top of one of the pins with a crayon or wax pencil, then place the plate in exactly the desired location and press down firmly on the marked pin. Now very carefully drill a shallow locator hole at the mark left by the pin. With the first pin and hole installed, the plate and the ribs have a connection and the second locator hole can be marked with great accuracy using the same method as that used for the first hole. Don't drill through the plates, it will show on the back plate if you do so.


    With locator pins installed, rapid and accurate placement of the plates is easy. The pins lock the plates in ther location while a clamping caul is placed on the plate to evenly press the pieces together. I don't need to use any clamps with the clamping caul. Placing some weights on the caul is one way to go, or I like to simply place the whole assembly under my overarm router (router removed) and lightly tap in a few wedges to apply even pressure. I timed the process and it takes me about 15 seconds to assemble and clamp the plate in place. It only takes a minute to glue on a plate with hot hide glue. Getting everything ready takes a bit longer.
    Attached Images Attached Images Closing the box with hot hide glue.-p1010018-jpg Closing the box with hot hide glue.-p1010008-jpg Closing the box with hot hide glue.-p1010005-jpg Closing the box with hot hide glue.-p1010019-jpg Closing the box with hot hide glue.-p1010025-jpg 

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  3. #2

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    Thanks for the insights! Very cool!

  4. #3

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    dampening the to be glued wood edges beforehand will give you a few seconds b4 dry time..also keeping a hot air blowdryer near will give you that much more time..

    good stuff mc

    cheers

  5. #4

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    Nice work, Matt!

  6. #5

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    Love the locator pins idea!

  7. #6

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    Nice stuff, Matt. I think some people also just take their sweet time applying the glue, and then give it a blast with a heat gun when they're ready to rock.

    Great to have some real life luthiers on here to balance out my half-assed offerings!

  8. #7

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    Thanks to everyone. I do have a heat gun at hand and some say I talk too much so there is plenty of hot air blowing around here in the shop. The pins prevent the plate from sliding around and smearing the glue. If you place the plate on the bottom and lower the ribs down onto the plate, the glue squeeze out is minimized and makes for easy cleanup with no glue running down on the ribs. The pins also give you assurance that nothing will slip out of position. No matter what glue you choose you may want to try these out.

  9. #8

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    Have you tried Norland fish glue for your guitar assembly? I've had great luck with it.

  10. #9

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    Quote Originally Posted by vejesse
    Have you tried Norland fish glue for your guitar assembly? I've had great luck with it.
    No I haven't tried fish glue. I have heard good and bad things about it but I have not used any myself. Some of the reports I have seen complain of an unpleasant odor associated with it. I use fresh liquid hide glue in some situations and have had good results thus far. Is the fish glue a collagen bond? If so, I would suspect there are similarities with hide glue in how they bond things. Collagen is what is holding all of us together right now.

  11. #10

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    Fish glue works the same way cooked hide glue does although I guess the way Norland processes the proteins water remains in the mix. But you can buy dry granulated fish glue as well. It doesn't smell bad in my opinion but I have received some bad granulated hide glue batches that smelled like ammonia or formaldehyde. I used to add 5% - 10% urea by dry weight to my cooked hide glue when I needed more open time but now that I found fish glue I don't bother with it.

    In my experience it has more body and gap filling ability when cured than hide glue does. It's maybe a bit more difficult to take joints apart later but it cleans up fully with water after cure, unlike Aliphatic Resin which always leaves rubbery remains in the pores of the wood after curing.

    In some forums guys were complaining about fish glued joints coming apart in extremely humid conditions, but I think hide glue would probably behave the same way. Maybe they were using old spoiled glue, but the stuff is so cheap I don't see why you'd keep liquid glue for years. If you keep it in the fridge I think it does last for years though.

    You mentioned liquid hide glue - do you mean Franklin liquid hide glue? That will open up at random and creep under tension badly.

  12. #11

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    I have heard that Franklin liquid hide glue can fail but I have never had a problem with it. I use a well dated bottle to glue fiber binding to wood and have been doing so for about 11 years now without any problems. It seems to bond the fiber better than hhg does. For binding, creep is not a concern. The binding is well protected from moisture by the finish over the binding so failure is not likely and would be an easy fix if needed. I am a creature of habit and use hhg for most joints in my mandos and guitars but I may have to try the fish glue. I know that many builders do like it.

  13. #12

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    I feel that hide glue and fish glue are more or less interchangeable. The things about fish glue that are pros can also be seen as cons. The longer open time means a longer clamp time etc... Fish is well suited to closing the box and gluing cello and bass fingerboards where you need to cover a good deal of real estate quickly. All the glues we routinely use are stronger than the wood so working properties and the in-service properties are the things we choose but we all know that. That said I am gradually moving away from PVA's and AR's in my guitar work... I do think fish glue smells absolutely horrid, by the way.

  14. #13

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    I have always used Titebond and I realize the hide glue has its benefits, but cannot really see the difference over titebond. Maybe hide glue is easier to get the joint apart if needed. I personally like the extra time of titebond I actually have been know to push that to the limit when it comes to crack repairs. It always seems like I get the all clamps in place and do a dry run and then something happens that I did not plan.......................

  15. #14

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    I don't think it's a crime to use Tightbond for a joint that has a lot of surface area and one you're not likely to take apart. And if you've got wood that's already a bit contaminated with yellow glue like a dovetail neck joint that you're regluing, you might as well use it because hide glue won't stick to yellow glue. But one thing I really don't like to use it for is on crack repairs on spruce and for splits in the sides and back. Because cracks sometimes will open up later, you've got a rubbery vinyl adhesive soaked in to that thin wood cross section you're trying to edge glue again. Might as well use hide or fish glue for gluing the edge to edge crack itself, that way it's possible to wash out the glue and try it again if it fails down the road. Because it's subject to thermoplastic creep I don't like to use it for unreinforced peghead repairs either, but it seems to work fine for just about anything as long as the gluing surface is large enough and the glue doesn't get too warm.
    Last edited by vejesse; 09-26-2016 at 12:17 AM.

  16. #15

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    I don't build guitars, but I do a little woodwork. Thanks for the tip, it's a great bit of cross-pollination.

  17. #16

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    Hide glue is a good choice for joints that are visible on the finished guitar. A well fitted joint can almost go unnoticed if the glue line is thin enough. Hide glue shrinks when it cures helping to close the joint. The joined plates of the back and the top are the most noticeable, but there are others that can be seen like the neck extension or the various neck laminations. One of the joints that can be a little tricky is where the ribs meet at the tail.
    Attached Images Attached Images Closing the box with hot hide glue.-p1010053-jpg