Masonite for Speakerboxes

I'm attempting to bend some 1/4" MDF in my current build.

I tried a dry run yesterday to bend two 1/4" panels around the braces using some clamping jigs i made. I had planned on wetting the panels before the process but wanted to see how much resistance the dry boards put up... Bad idea. Didn't seem like they were putting up too much resistance, but when i took a closer look i noticed they split before i torqued the clamps all the way down.

I imagine things will go better if i wet the boards. But that raises another question. What is the effect of wetting the boards on the glue that i use to laminate them together and to glue them to the rest of the cabinet? Glue cleans up nice with a wet rag. Will a wet panel screw up my glue's ability to set? I think white and yellow glues dry by evaporation? In that case i imagine things would be fine when the boards eventually dried? Anyone?

In any case, i'm going to try to find some 1/8" MDF but don't expect success. I think masonite is easier to find. It comes thin and bends easy. I did some searches but only found one thread talking about using it in speaker builds - and the poster was going to glue it to hardwood, which raises it's own set of problems.

Has anyone used masonite directly for the walls of a curved cabinet? I would be veneering over it.

Thanks,
Joe

Thanks for the comments guys. I'm going to give the MDF bending another shot this weekend. If it doesn't work out i'll have to decide on either plywood or masonite.

I have wet down MDF before for several reason... i've bent MDF before, but previously i kerf'ed it first (see my curved sig build links). A moderate amount of water on the surface (i didn't soak it in a tub or anything) helps it bend without cracking and doesn't destroy it. I also do most of my veneer work with hide glue and a veneer hammer. That technique involves a good amount of water too. Masonite will definitely get ruined by water over time (my buddy had an out door ramp with Masonite top-layer), but i'm not sure if a quick wet-down will kill it. I doubt i would need any help to bend that stuff though.

Now particle board on the other hand - if that stuff so much as sees a drop of water it swells up and turns into a mess. Haven't used that stuff since the good old high school car audio days though

I've never built a speakerbox from plywood. I was under the impression that it was an absolutely terrible idea. Since joinging this forum, I have seen a lot of good builds that use it so my opinion has been swayed. However, recently i saw a build that exactly demonstrated what i worry about. I meant to save a link to the thread because it was such a good example but i never did. I can't even rememeber any of the details so i doubt i will be able to find it.

The guy ended up having to do a good deal of patch-work to fill in voids. And there is always the risk that there is an internal void that you can't see that will vibrate. These are my main gripes about plywood.

If you have access to high quality plywood i suppose this is less of a worry. But MDF is as consistent as you can get, and that's what i like about it. The mess it makes is And the wear on tools is But it cuts clean and routes smooth, so i think i'll probably continue to work with it.

Good to hear some opinions though.

I wet down my MDF this morning and clamped it in place. We'll see tonight how it comes out.

Working with MDF absolutely requires a mask/respirator without question.

You never have problems with voids? I hear baltic birch is the plywood of choice but is expensive and hard to find. Is that what you use? Where do you pick it up?

Thanks for the material recommendations Bill. I might rebuild my Zaph 5.3 cabinets... After a year the screws i used are starting to telegraph through the super thin paper backed veneer Maybe i'll try plywood. For a small tower like that, you think 1/2"?

Voids that vibrate because the panel is unbraced is one concern. Another i've seen people complain about is hitting a void when drill mounting holes for the drivers. Hurricane nuts and sealant can fix the problems - just a few issues that don't crop up with MDF...

Obviously, other issues do appear - like denting the edge of an MDF panel if you drop it from more than 2". Or horrible splitting if you use screws and don't predrill. On top of the dust and weight issue.

Beast, is this the build you're talking about ?

Looks like you did a lot of sealing on that sucker.

That's not the thread i'm thinking of though... pretty sure it was a sub build, but can't remember who/what/when.

ah, yes, i found where you mention air leaks through voids.

I think i might be mixing up two different ply-wood disaster builds in my head... your comment about the air leaks was something i remember. But i also remember a specific series of pics (i guess from another thread?) where somebody had to do a ton of bondo work because the edges had big voids in them or something.

Beautiful theatre, by the way nice dog too

Thanks Jay1... your Budget Surround Build was indeed the exact thread i was thinking of. Glad you chimed in because it was driving me crazy not being able to find it.

I thought it was a sub build, but like i said, i think i combined Beast's build and your build into one mental note - the gist of which was to never ever use cheap plywood

Thanks Noah. Definitely more expensive than MDF, but maybe i'll give it a shot on my next small-ish build. Does the 1/4" bend ok or do you have to go down to the 1/8"?



DonoMan - i switched up my build technique shortly after that Zaph build and no longer use screws... just glue and clamps. For that Zaph build i countersunk the screws and filled them (can't remember if i used bondo or something else). The problem is that i didn't do a great job sanding down the filler. I have tiny bumps where the screws were. My wife was nice enough to say she can't even see them - but i can. Just depends on the lighting.

I was using coarse thread drywall screws. They hold OK in MDF, but you definitely don't want to over-tighten them or they won't hold. And you have to predrill or you get a mess.

Good info in this thread. Thanks guys