Screwing ends of ply/General cabinet help

[lost eden]

I'm planning a new boombox build over the summer, pretty finalised on the design & already bough most of the parts. However I've never actually built a proper speaker enclosure before so I need some guidance & tips on it.

I was planning to use 12mm birch ply, because that's what the original Boominator used & it seems a fairly sensible choice. The only power tools I have at home are an old 350W drill & a Dremel, so I was planning to find a CNC company or similar who could machine the wood for me, or at least do the large work (cutting to size/shape) & the complicated work (routing the flange for the mid/bass) leaving me just to drill the pilot holes for the screws. This is where I hit a problem. Beneath is the design as it stands atm;



In hindsight I've gone completely overboard with the number of screw holes & I could probably make do with less than half that number, but the real problem is screwing into the 'sides' or 'ends' of the ply, such as for the screws that hold the front piece to the sides, top & bottom.

The pieces will of course be glued & probably sealed inside with silicon, but I'm going to need to screw them as well. So, am I going to stand a chance at all of being able to screw into the ends? Will I have to drill pilot holes & if so how do I drill into a perpendicular piece of layered wood without splitting it? I'll have to buy clamps from somewhere I guess.

Also, what sort of screws should I use? At the moment I just made all of the holes 6mm diameter & 36mm deep, but it will ultimately depend on what type of screw is best to use.

Would I be better off using MDF or hardboard, as I presume you can screw that in any direction without different concerns?

Finally, what is the best way to treat/finish/paint/seal it? Can I just spray it whatever colour I want & then put layers of clear varnish on top to prevent moisture from seeping in & warping it?

Sorry for all the beginner's questions, it's been a long time since I did any proper woodwork...

[badman]

Usually you'd use cleats at the edges/corners. Blocks of solid wood that you can screw into. Quality ply is preferred over MDF. Sometimes you can find something decent at home depot/lowes, but local lumber suppliers probably have proper baltic birch ply in 60" sheets.

With glue, you DEFINITELY don't need that many screws, I'd use much fewer and only use them for holding things together while the glue cures. After that you can remove and fill them, or just leave them and fill over top.

Buglehead screws are preferred- the ones with the conical heads.

[lost eden]

Sorry if this sounds really dumb, but by 'solid wood' for the cleats, what sort are we talking about? I presume it's real wood, as opposed to ply/particle/MDF/chip? Sort of like 1" square lengths the DIY store probably has?

With birch ply will I need to countersink the pilot holes using bugleheads, or will brute force on a good ratchet screwdriver be enough?

[badman]

Originally Posted by lost eden

Sorry if this sounds really dumb, but by 'solid wood' for the cleats, what sort are we talking about? I presume it's real wood, as opposed to ply/particle/MDF/chip? Sort of like 1" square lengths the DIY store probably has?

With birch ply will I need to countersink the pilot holes using bugleheads, or will brute force on a good ratchet screwdriver be enough?

yes, "real wood", 1" square lengths would be fine if you can make your pilot holes precise enough.

Countersinking isn't strictly necessary though you'd want to use the drill to drive them, by hand, they won't sink in as well without a countersink. If you're going to leave screwheads exposed, countersink and screw by hand, if you're going to fill and paint/veneer over, just use the drill to set them in to the right depth- be careful not to overdo it and damage the material, natch.

[kevinahcc20]

I have screwed into the "end-grain" of quality 3/4" ply with no problems whatsoever using #8 screws with properly sized pilot holes including countersink for the screw head. If you are using cheaper ply (not recommended) you may have some screws that end up in a void in the plies and have no wood to thread into. It works best and fastest if you buy a drill with countersink built in and the drills with tapered bits are preferred. At 1/2" ply like you are planning I would downsize to a #6 screw and it will be more critical to make sure the pilot hole is centered in the plywood and straight to avoid problems. A quality plywood (many thin plies & free of voids) will work better than MDF or hardboard as these materials tend to split when screwed into on edge. If you must go MDF I would not go thinner than 3/4" and I would use conformat type screws that are specifically designed for MDF. These screws can usually be bought with a mating drill bit for best results.

[mymindinside]

If you're going to glue them up anyway, why not use nails? alternatively clamp them in place while the glue sets....

cheers,
mymindinside

[lost eden]

Originally Posted by mymindinside

If you're going to glue them up anyway, why not use nails? alternatively clamp them in place while the glue sets....

cheers,
mymindinside

Why didn't I think of nails...

So am I right in thinking that as long as the cabinet is designed properly, braced properly & glued properly, the screws don't actually serve any purpose except holding the pieces together as the glue sets? If so it might be better investing in some clamps & completely forgetting about screws/nails/cleats/etc.

[Andersonix]

Nails (preferably from a nail gun) or screws help keep things in place while clamping, as clamping glued joints makes the pieces want to slide around....

[richie00boy]

Have you got a router? If so then cut rebates so that your panels don't slide around. Then you won't need any screws and not have to fill them and can also do nice rounovers to make your cabinet edges safer and more robust

[nigelwright7557]

I have found the best way with ply is to use 2by2inch bracing and screw into that.
You will end up with a really solid box.