What glue to use

[feverdog873]

Hey everybody. I'm just starting to work on making a set of loudspeakers, and I was wondering if you guys had any recommendations on the type of glue that I should use. My uncle suggested urea formaldehyde glue, but I was wondering if you guys had any other suggestions. Thanks.

[Saturnus]

Depends on what materials you want to glue together and the properties of the bond you want.

Generally speaking your local hardware store will most often give excellent advice on which glue is best suited for which purpose.

[Aengus]

My uncle suggested urea formaldehyde glue

Wow - maybe he makes plywood for a living? For speaker building, I strongly recommend avoiding urea formaldehyde. It's a nuisance to use and it's bad for you.

To glue most woods, plywoods, particle board, and so on, you can use PVA (polyvinyl acetate) glue, normally sold as white glue or yellow glue. Titebond II or III are good, though somewhat expensive. Titebond III is waterproof, not something that many speakers require.

I've had good luck with the Lee Valley brand PVA glue as well. PVA glues clean up with water (before they dry).

To glue metals to plastics to wood in some combination, you'll need an epoxy or something like Gorilla glue - both are messy and a bit expensive, and need acetone (for epoxy - can't remember for Gorilla) to clean up; acetone is not nice stuff, so use lots of ventilation if you go this route.

Feverdog873 (I'd never have guessed there were that many) is right in suggesting that the place you buy your materials should be able to give you good advice as well.

If you want more information, ask a more specific question (explain just what you want to glue, for example).

Regards.

Aengus

[HK26147]

I use urethane based glues. Sometimes gorilla glue and sometimes PL urethane construction adhesive.

Syd

[Ron E]

PVA for normal duty, Polyurethane if you need a longer open time for complex builds.

[Drew Eckhardt]

Originally posted by feverdog873
Hey everybody. I'm just starting to work on making a set of loudspeakers, and I was wondering if you guys had any recommendations on the type of glue that I should use. My uncle suggested urea formaldehyde glue, but I was wondering if you guys had any other suggestions. Thanks.

It depends on how you're planning on building your speakers, how accurate your joinery is, and maybe how many clamps you own if you don't plan on screwing and gluing (which then requires filling the holes).

For simple butt joints in plywood and MDF, yellow wood glue (Poly Vinyl Acetate, like Titebond or Titebond Extend if you want a little more working time) is inexpensive, cures quickly (you can have the clamps off in an hour), yields "invisible" glue lines, and cleans up easy with water. It needs 150-250 psi of clamping pressure to form the strongest joint.

If you're going to glue up panels or use miter joints, you want to use something with a much longer open time than Titebond Extend (discovered this the hard way, although it saved me from finishing something in birch with a veneer too thin to sand). I've been using T-88 epoxy (about 45 minutes of pot time and hours of open time). It doesn't require any clamping pressure. It'll fill gaps where there are errors in miter joints. Plastic resin (Urea Formaldehyde) should be similar but I haven't used it.

[Drew Eckhardt]

Originally posted by Aengus
To glue metals to plastics to wood in some combination, you'll need an epoxy or something like Gorilla glue - both are messy and a bit expensive, and need acetone (for epoxy - can't remember for Gorilla) to clean up; acetone is not nice stuff, so use lots of ventilation if you go this route.

White vinegar cleans up uncured epoxy from tools and people.

Alcohol works too.

Acetone is a bad idea, especially for people since it will carry the epoxy through your skin into your blood stream.

You do need to wear gloves. Every one is allergic to epoxy and enough exposure will sensitize you so you can't use it in future projects. It's too useful so you don't want that.

Measuring accuracy is important. For small quantities you pretty much need to use a digital scale.

[Drew Eckhardt]

Originally posted by Ron E
PVA for normal duty, Polyurethane if you need a longer open time for complex builds.

It's on the order of 20 minutes which isn't appreciably better than Titebond Extend. Epoxy can get you 45 minutes of pot life and hours in the assembly (in a thin film the heat from curing isn't as concentrated).

[Saturnus]

This is why I suggested asking your local hardware store for the best advice with the material you're going to use.

Things to consider is:

Curring time - if it's a large complex structure of many different parts you might require even very long curring times

Clamping pressure - some glues require high pressure to bond correctly, others require almost no pressure.

Expansion - some glues expands to fill tiny gaps if the bonding surface isn't perfectly smooth

Chemical alignment - some types of wood like plywood and MDF contains glue of their own, these don't always work with other types of glue

Flexibility - some glues make very hard but brittle bonds that doesn't handle vibration very well others are very flexible but doesn't bond as well and would need additional fixation like screws or dowels.

And if you're laminating different pieces of wood or other materials you might want to consider vibration absorbing "glues" like tarmac tar or silicone based glues.

[AMV8]

Hi Feverdog873

Your final choice of a glue will depend upon the material used for the cabinet and probably also the use of the cabinet.

Some glues set very rigid. Such glues may crack if use for a subwoofer cabinet.

I normally use a traditional wood/ply glue for a large cabinet such as a subwoofer. For a smaller mid/treble cabinet a PV glue is probably ok and is easier to use.

Don