I tried doing a search for this, but found literally tens of thousands of threads that contain all the different keywords I tried.
I'm looking to build my first set of speakers (a transmission line using small Tang-Band full-rangers), and I've run into some confusion about what glues will and won't work with MDF. So, to cut to the chase, I already have a bottle of Gorilla Glue from other projects around the house. Will that work? Do I need to go buy something else?
Thank you for the help.
I'm looking to build my first set of speakers (a transmission line using small Tang-Band full-rangers), and I've run into some confusion about what glues will and won't work with MDF. So, to cut to the chase, I already have a bottle of Gorilla Glue from other projects around the house. Will that work? Do I need to go buy something else?
Thank you for the help.
You could just use regular yellow glue (such as titebond) . Gorilla glue (and PU glues in general) expand a bit when curing (useful for filling voids) but make sure the pieces are clamped well (to prevent them from slipping/shifting) .
Don't ask me how I know this 🙂
Don't ask me how I know this 🙂
Gorilla Glue
I prefer TiteBond and pretty much any professional wood glue to gorilla glue. Water cleanup and a beautiful bond without the expansion problems of polyurethane glue are my reasons. I have read tests on Gorilla vs Titebond and with Titebond, the wood will fail before the joint will and the opposite is true of the polyurethane.
I used Gorilla Glue on an outdoor project last summer and was not impressed. If you do use it, make sure NONE of it gets on your skin.
I prefer TiteBond and pretty much any professional wood glue to gorilla glue. Water cleanup and a beautiful bond without the expansion problems of polyurethane glue are my reasons. I have read tests on Gorilla vs Titebond and with Titebond, the wood will fail before the joint will and the opposite is true of the polyurethane.
I used Gorilla Glue on an outdoor project last summer and was not impressed. If you do use it, make sure NONE of it gets on your skin.
I was specifically told that water-based glues will not work on MDF because they won't soak into the material, and that a solvent-based glue is required. I have some Titebond laying around somewhere, too, and if you all think that works just fine, then that's more than good enough for me. 🙂
Titebond III
I like this as well as it offers the workability and cleanup of I and II but is also waterproof (if you need that).
I like this as well as it offers the workability and cleanup of I and II but is also waterproof (if you need that).
A: Titebond is NOT waterproof. Its darn good wood glue but its not waterproof. Try it on your deck once, you'll find out in the first rain strom.
B: Polyurethane glue is moisture activated. In other words you need to wet down both surfaces to get a maximum bond. By the way it is quite waterproof. I've used it on my redwood deck. Regardless, it is an absolutely fabulous bonding agent. Remember it foams and when hard it is almost impervious to anything. It does sand quite well though. It really is superb stuff. So, clean it up along the way (paint thinner).
Heck, the only thing that is actually waterproof are "some" epoxies. Even Gelcoats (fiberglass boats) are NOT waterPROOF. Actually almost nothing is.
The use you are speaking of is the biggest issue. If you are gluing joints, PVA glues are excellent. Elmers, Titebond and numerous others. Frankly, they're all quite similar. All are stronger than the wood itself.
If you're edge gluing anything I'd be inclined to use Urethane glues. It is just impervious to anything and everything. Especially if you're going to be machining it.
Regardless of your choice all of your joints should be physically clamped and nothing should be without countersunk screws. Even done perfectly (which really is very easy) all joints should be sealed with something on the interior of the enclosure. Hot glue is superb if your finger can handle it. So is silicone. That's just excellent. Actually Vulcom Urethane caulking is a pretty darn good choice as well. It NEVER deteriorates, never.
Fill all of your screw holes with water putty or something like that (plastic wood filler). Use a wide blade knife (maybe 6") to spread it consistently. Mix it thin and use two-three coats. Sand them flush and DON'T oversand. Use a machine sander that doesn't require much pressure, like a Bosche or hand sand the final. Don't go lower than 100 grit. All of your veneers, regardless of type depend on the validity of your surface preparation. Clean, clean, clean! Use something like denatured alcohal.
Good luck!
B: Polyurethane glue is moisture activated. In other words you need to wet down both surfaces to get a maximum bond. By the way it is quite waterproof. I've used it on my redwood deck. Regardless, it is an absolutely fabulous bonding agent. Remember it foams and when hard it is almost impervious to anything. It does sand quite well though. It really is superb stuff. So, clean it up along the way (paint thinner).
Heck, the only thing that is actually waterproof are "some" epoxies. Even Gelcoats (fiberglass boats) are NOT waterPROOF. Actually almost nothing is.
The use you are speaking of is the biggest issue. If you are gluing joints, PVA glues are excellent. Elmers, Titebond and numerous others. Frankly, they're all quite similar. All are stronger than the wood itself.
If you're edge gluing anything I'd be inclined to use Urethane glues. It is just impervious to anything and everything. Especially if you're going to be machining it.
Regardless of your choice all of your joints should be physically clamped and nothing should be without countersunk screws. Even done perfectly (which really is very easy) all joints should be sealed with something on the interior of the enclosure. Hot glue is superb if your finger can handle it. So is silicone. That's just excellent. Actually Vulcom Urethane caulking is a pretty darn good choice as well. It NEVER deteriorates, never.
Fill all of your screw holes with water putty or something like that (plastic wood filler). Use a wide blade knife (maybe 6") to spread it consistently. Mix it thin and use two-three coats. Sand them flush and DON'T oversand. Use a machine sander that doesn't require much pressure, like a Bosche or hand sand the final. Don't go lower than 100 grit. All of your veneers, regardless of type depend on the validity of your surface preparation. Clean, clean, clean! Use something like denatured alcohal.
Good luck!
I like the Titebond as well, but I'm a pretty lousy woodworker and don't do that many projects. Thus, whenever I buy a bottle of glue, I use a permanent marker and put the date on the bottom. I toss it at two years, regardless. I'd rather spend a few bucks extra on glue, than have a project come apart. Should probably do that with finishes as well, especially shellac!
Well, okay, I meant to say an organic solvent-based glue.
Either way, I know how I'm going to proceed from here.
Either way, I know how I'm going to proceed from here.
lose the screws
You can save the time and effort of putting in countersunk screws everywhere if you have a lot of clamps OR a nailgun. I have used an 18 gauge 2" long nailgun, which you can get pretty cheaply from harbor freight or other places like that, and the boxes go together real quick and tight. Just make sure your cuts are accurate. Or shoot a bead of caulk inside after the glue sets.
You can save the time and effort of putting in countersunk screws everywhere if you have a lot of clamps OR a nailgun. I have used an 18 gauge 2" long nailgun, which you can get pretty cheaply from harbor freight or other places like that, and the boxes go together real quick and tight. Just make sure your cuts are accurate. Or shoot a bead of caulk inside after the glue sets.
Caulking the inside is going to be a real trick, since the last panel to go on will not be caulkable. It's a long, skinny box with a small driver opening. As a result, I want to get as tight as I can, and "glue and screw" seems the easiest way to go about that using the tools I have.
EDIT: Scratch that. I've figured out a way to seal up the inside with this enclosure.
EDIT: Scratch that. I've figured out a way to seal up the inside with this enclosure.
When working with the MDF I get locally and the generic yellow carpenter`s wood glue (like Elmer`s white glue) I find I have to break the smooth surface on the MDF panel with a power sander and coarse grit sanding disc where the glue is to go otherwise it can break away clean from the panel once cured. This is a huge pain in the a$$ as a time waster and it messes up the smoothness of the wood next to the joints unless one keeps the abrasion `inside the lines` which I sometimes have to map with a straight edge in pencil. I always clamp my joints.
My MDF has a hard finish on each side like the smooth side of pressed masonite. Is this a material problem?
What am I doing wrong?
My MDF has a hard finish on each side like the smooth side of pressed masonite. Is this a material problem?
What am I doing wrong?
Butt joints are not that strong all by themselves, regardless of the material and the glue. That's why people either screw them or nail them or dowell them or rabet them or reinforce them with biscuits or metal braces, etc. I doubt it's a question of what glue you use or your technique, it's just a characteristic of this type of joint. You'll never see furniture makers use butt joints without some sort of mechanical reinforcement.
Get yourself a biscuit jointer and learn how to use it, and you will find it eliminates the need for screws, keeps your pieces in line as you assemble them, and you'll never have a joint fail on you again. See here (registration required) for much more info.
Get yourself a biscuit jointer and learn how to use it, and you will find it eliminates the need for screws, keeps your pieces in line as you assemble them, and you'll never have a joint fail on you again. See here (registration required) for much more info.
David94114 said:
David,
You misunderstand my problem. The edge of one of the joined pieces with dried glue showing a glass smooth surface, as though one tried to butt joint the edge of MDF sheet to a sheet of smooth teflon, just pulls away from the other sheet at the joint. The glue wets the smooth panel surface of the MDF but does not get a grip. Once I break the glaze before I glue and clamp the joint cannot be pulled apart, the wood will crumble apart first, elsewhere to where the glue is. It is an interface problem.
I do already employ dowels and woodscrews liberally as needed, as well as gussett blocks. Sometimes homemade biscuits.
In that case, I'd suggest trying a better grade of glue like Titebond instead of generic, and/or check that your glue is not too old.
Also, what is your technique for applying the glue? You want to be sure that you are applying some to both sides of the MDF before joining, and that you smooth it out with a finger or applicator before sticking the two pieces together. This kind of glue is not designed to span spaces, but to work with a thin, even film, with no gaps or voids, such as is generated when you clamp the pieces together and squeeze some out under pressure.
I realize that it works fine when you sand the glazed hard surface off the MDF. But every piece of MDF i've ever worked with has this type of surface, and I've always been able to glue it without difficulty. So perhaps when it is sanded off, it will bind without optimum glue or optimum gluing technique, but when the hard surface is intact, these sorts of things will make the joint fail.
FInally, and this is a long shot, but is the MDF fresh or perhaps you are using an old sheet that someone might have spilled something on or sprayed something on that interferes with glue adhesion?
Also, what is your technique for applying the glue? You want to be sure that you are applying some to both sides of the MDF before joining, and that you smooth it out with a finger or applicator before sticking the two pieces together. This kind of glue is not designed to span spaces, but to work with a thin, even film, with no gaps or voids, such as is generated when you clamp the pieces together and squeeze some out under pressure.
I realize that it works fine when you sand the glazed hard surface off the MDF. But every piece of MDF i've ever worked with has this type of surface, and I've always been able to glue it without difficulty. So perhaps when it is sanded off, it will bind without optimum glue or optimum gluing technique, but when the hard surface is intact, these sorts of things will make the joint fail.
FInally, and this is a long shot, but is the MDF fresh or perhaps you are using an old sheet that someone might have spilled something on or sprayed something on that interferes with glue adhesion?
To pile on at the last minute and add my $0.02, I use Titebond II pretty much exclusively when I am working with MDF. Elmers and the original Titebond seem not to stick for me either, just as described. The Titebond II seems to work much better for me, though I don't really know the reason.
As an aside, Titebond III is rated as waterproof. I would not trust it submerged, but I have seen it hold up on outdoor furniture very well. I absolutely hate gorilla glue, and Titebond III has been great for me for outdoor woodworking projects I have used it for.
David
As an aside, Titebond III is rated as waterproof. I would not trust it submerged, but I have seen it hold up on outdoor furniture very well. I absolutely hate gorilla glue, and Titebond III has been great for me for outdoor woodworking projects I have used it for.
David
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