Hey guys ...
While building subwoofers it is understood to hold the wood pieces tightly together.
But what if we uses excessive force with clamps ??
The glue will come out, leaving only a thin film inside.
I am talking about a 90degree joint between any two box walls.
Is it not better to apply just enough and moderate force so that the two wood pieces come close without any gaps, and still decent amount of glue remains inside ??
While building subwoofers it is understood to hold the wood pieces tightly together.
But what if we uses excessive force with clamps ??
The glue will come out, leaving only a thin film inside.
I am talking about a 90degree joint between any two box walls.
Is it not better to apply just enough and moderate force so that the two wood pieces come close without any gaps, and still decent amount of glue remains inside ??
I agree that a thin coating is better, however I use TiteBond2 and I've never been able to pry boards apart - the boards splinter or shatter before the glue ever gives up.
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There is an amount called 'hand-tight'. It is not the most you can do with your hands, it is only 'firm'. Yes, too much will squeeze out the glue, but tighten enough to bring the two surfaces together.
Yes, when used properly the glue is considered to be stronger than the wood.
Yes, when used properly the glue is considered to be stronger than the wood.
That's wrong. If you glue two boards together, apply pressure, it will break the wood and not the glue. Unless you've let the glue freeze (the ice crystals break the long molecules of a PVAC glue) or you 'stretch' it with water.
For anyone curious, just let a blob of glue dry and then test it for strength. Modern white and yellow glues will actually stretch quite easily. The strength of the joint comes from the glue penetrating the wood fibers. That is why when you think you have squeezed it out, it is actually going deeper into the fibers and providing a stronger joint.
Note the older hot hide glue is probably the weakest glue, but in good furniture has the advantage of ease of repair.
Next we can discuss the difference between yield strength and failure.
Note the older hot hide glue is probably the weakest glue, but in good furniture has the advantage of ease of repair.
Next we can discuss the difference between yield strength and failure.
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What's the type of furniture glue that eventually turns to powder? Quite a bit of my older furniture seems to have been put together with that glue, and most of the pieces basically fell apart after about a decade of use. It was used as both a glue and a filler, so I know it likely wasn't common wood glue.
I've done plenty of wooddorking and all glues have worked for me including using my daughter's old elmers. That said, I used PL glue for my Keystone sub with some bar clamps to line things up and fastened with 16ga nail gun and it is easily the strongest I ever built.
I could be wrong Brian but I think that is hide glue and can be reactivated with heat and moisture. There are some purists that believe in the stuff so it can be fixed later.
I could be wrong Brian but I think that is hide glue and can be reactivated with heat and moisture. There are some purists that believe in the stuff so it can be fixed later.
Sounds like hide glue that's been dried out from air conditioning or similar low humidity environment.
Bottom line is the glue is what's holding the wood together, not the wood. If it breaks somewhere other than the glue joint, the glue has not failed. If it breaks at the glue joint, not enough glue was applied. Or the glue was inferior, deliberate or not. Sometimes you want it to break at the joint to save the wood. But strong glues are far stronger than the wood being glued. Tite-Bond is a good example.
Indeed.
That's why I posted the Tite-Bond.
That stuff is the greatest!
Before that, I used to use Elmer's Carpenter Glue, I still have some around, and even THAT glue has never failed me.
I re-glued my wobbly dining room chairs with it 15 years ago, and through dinner parties and fat people 😱 sitting on those chairs, they're still tight and solid.
PVA flows and gets absorbed into the wood fibers, releases it's moisture as it cures. Too much clamp pressure can lead to a weak joint. You don't want to squeeze the glue out completely. Best is too apply enough glue to the joint, thin coating. I usually would coat both surfaces. Hardwoods want more clamp force than softwoods do. Manufactures recommend 150lb. softwood and 250lbs. for hardwoods.
Try to avoid applying more force to make a poor joint work. The joints should be tight within reason.
Try to avoid applying more force to make a poor joint work. The joints should be tight within reason.
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I like to add strength on the inside of corners with 1/2 inch or 3/4 inch square wood strips.
Glue, then either staple, tack nail, or screw into the inside of the joint.
Glue, then either staple, tack nail, or screw into the inside of the joint.
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That's true, though at the same time it doesn't necessarily say it's a bad glue, the leg got a lot of leverage and the leg can't be mounted very deep, it's just a few cm at most. Many chairs are not used on really even ground and moving on the chair or balancing on two of its legs can loosen the leg over time even with good glue. If you've got problems with the chairs, mount them with glue, a slit in the top of the leg and a small wedge in it. Very rugged, strong connection, the wood of the seat splits before the leg comes out. Drawback: Don't think about remodeling them. 😀 🙄 😉
That's caseine or maybe bone glue. PVA glue was invented in the 50s and the other glue types vanished mostly over the years, the new glue was better in almost all criteria (heat can be an issue, it becomes liquid again).
I can only agree on that. Another thing that should be avoided is adjusting the position of the parts of the joint half way through curing.
Another thing which heavily weakens the glue is frost. The ice crystals destroy the long molecule chains. That is for liquid glue, glue joints can withstand freezing cold easily because the water evaporated while curing or was absorbed by the wood. That means, do not store wood glue in the garage or basement if it can reach temperatures below ~4°C
Polyurethane glue is an alternative for problem joints like angle cuts which don't fit perfectly together or for furniture in moist rooms, not getting soft or washed out by heat or water. A life saver on projects like the Klipsch corner horn or similar complex speakers. Can also glue plastic and other materials.
Downside: It will always have a glue gap/seam, no 'zero gap' joints. And once cured you can only remove it mechanically (on clothes, fingers etc not a nice thing. Believe me, I know from experience. 🙄) Always needs clamps or straps, otherwise it pushes the parts apart as it expands. Short shelf time, you should use it up within 1-1,5 yrs.
To use edge wood strips is a nice way to glue the enclosure without clamps and to save waiting until the glue cures. Good tip. Depending on what you're doing with it later, it might be a good idea to get the screws out after curing. Your router bits and circle saw blade will thank you if you want to add bevels or rounding the edges. 😉 Tack nails are usually soft enough to not leave a mark on the router bit.
Screws and nails are just used to hold the pieces when there is no clamping surfaces... The glue should do all the work. The combination of a good solid wood joint and glue have been sufficient for longer than we have been around. That said, I've used screws and nails before, but always tried other methods before going to them. Sometimes tho, you just need to use mechanical fasteners without reinventing the wheel. Would never fault someone for that. Just know, hiding holes in some woods is an art all in itself. Even paint won't hide some fill jobs.