Recommended glue for glueing plywood to MDF?

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Hi, am building my first diy loudspeakers.

Iv'e built the cabinets out of MDF, am using stained 3.6mm plywood instead of veneer. Can anyone recommend a glue to use? I was thinking a quick drying contact adhesive and maybe drying the glue in vacuum bags.

Any advice will be much appreciated, thanks.
 
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Gee, I'll beg to differ on using contact cement and either raw natural or paper backed veneer - particularly if planning to use any solvent based finishing materials - ask Scott about a recent experience

There are new specially formulated single and 2 part adhesives for veneers, hide glue has been around for a while, and I've been ironing on with the same yellow PVA wood glue as for cabinet assembly for well over 10yrs with no issues (other than occasional careless layout or starving glue resulting in bubbles - but those are my fault, not the process)

Andrew, I'm not sure I got your point - all assemblies with MDF will have some end "grain" joints, whether simple butt joints, mitres, dadoes, what have you.

I use plywood myself almost exclusively, but on the few occasions where asked to build with MDF and veneer, I'll give the entire surface a thorough sanding with 80G to break through the tempered surface skin and permit better penetration of the glue for the veneering process.
 
Well that's probably more important really for "veneering" i.e. thin raw or backed veneers, than for the described application of finished plywood skins ( I assume no thicker than 1/4"). For adhering such skins with glue rather than contact cement, you'll need to be sure you've got evenly distributed pressure to ensure full adhesion, either by vacuum bagging or cold pressing with platens of scrap material larger than the face panels and weights. It might not take tons of weight to equal the pressure of 14.7 lb psi., but it's the uniform distribution of that pressure while the glue is drying that counts.
 
Thanks Andrew, do you think I should apply glue on the end grain of the MDF let it dry, sand it, then apply the plywood?

I wouldn't do that, it's simply not necessary to seal MDF end grain on a simple butt jointed box. In fact you will probably make it weaker as PVA doesn't stick very well to itself.

I also wouldn't bother sanding the good faces down either. Just make sure they are clean and free of dust and fingerprints and oils etc. PVA will soak in no problem.
 
richie - if not clear my comment re sanding the MDF was in the context of veneering.

I've found it gives much better adhesion when using the iron-on method and yellow PVA glue, and since you'll want to sand all exposed joints anyway to clean up squeeze out and telegraphing of less than perfect seams, it doesn't really take all that much longer with a RO sander.
 
when applying titebond, I like to use a squeegee (the edge of a credit card works well) and I like to apply it to both surfaces. A brush or roller applies way too much glue. Also, make sure to get 100% coverage of the surfaces with glue.
 
There's a lot of movement in the first 30 minutes after applying the weight, yet had no problems so far.

Iv'e done the back panel of the cabinet first and its had weight on for 15 hours, should I leave it for 24 hours before removing the weight and trim the edges? Thanks again.
 
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