I think i've heard someware that you dont wanna leave any panel much more that 10" without bracing?? Meaning the most unbraced area you would want is 10" i guess. I've found a few pictures heres the links
Thomas W's Aerial stryke subwoofer (lots of bracing) Link Removed
Here's a method I've used for many years (actually since I got into this hobby). It works well even without additional bracing, though since my latest box was about 9.7 cubic feet and had some rather large flat panels, I went ahead and braced it. What I like is that I only need a couple C-clamps to put the box together, but I expect it's probably a much slower building method than the usual box made with a heap of bar clamps.
That subwoofer is truly a work of art. It's a shame all that beautiful interior work goes unseen, but the ouside is even better. Tell me, did you use a CNC machine to cut all the holes in the braces, or was that done by hand with a router? That's a lot of hole cutting! I probably would have used a fly cutter on my drill press, er well probably not in MDF, but ply or particle, sure. You could probably sell that thing for several thousand dollars if it was at a high end retail store.
Thanks for the compliments. I cut the holes with an adjustable carbide hole cutter on my drill press. I then routed the cut outs for a nice smooth finish. I put quite a bit of work into that sub and it served me well. I ended up selling it locally for a mere $400, just enough to get some of my money back. Hard to sell a used sub for any money. It was a wonderful sub and I miss it but I moved up.
Adjustable carbide hole cutter? I like the sound of that. Where does one get such a contraption in these parts?
I agree on selling used DIY speakers, it's hard to do and break even, much less make money. Of course the option is to sell at a loss, or not sell (netting $0) and end up with a house/garage full of speakers you don't use. The best you can hope is that if you do part with your own speakers, they go to a new owner who can really appreciate them.
I've got a fly cutter very similar to that, except mine has two blades (one on each side), and I got it at Harbor Freight. It doesn't seem to work nearly as well as the one my Dad has though, which is a single blade. Maybe it's just a low quality cutter, wouldn't surprise me. I thought Darren was speaking of a different kind, but could be just a fly cutter with a carbide blade. Mine only goes to 5" though, which is a major drag when mounting a 6.5" woofer.
I like it! Have thought of using dowels in the past, never got around to it though, probably because I'm even too cheap for that. I can't remember how much a 8' length of 1.5" dowel is, but I seem to recall it's quite a bit more than an 8' 2 x 2. Of course the dowel has the advantage in that you can inset it into the panels perfectly with just your spade bit, which should make a much stronger joint than just a butt joint type brace.
What do you mean just along the inner edges? Do you mean just around the perimeter of the panels? If so, well that all depends on the thickness, stiffness, and size of the panels. I think the recommendation of keeping the widest open span on any panel 10" or less is a good one, though in some cases it will be overkill. And in fact, when you think about it, that means you can't use larger than a 10" woofer. My box' top, bottom, and sides all have an open span of 15", but it's plenty stiff.
Oops, I forgot you had actually said how large the box was going to be, 1.6 cubic feet. That is relatively small, say no larger than 16" x 16" x 16" internal, allowing some room for the driver/amp/bracing/port. Assuming you are using 2 x 2's for the bracing on all edges, that leaves a maximum open span of only 13", assuming it's a cubical box. Given a 1.5" baffle and 3/4 thick everywhere else, I don't think you'd need any bracing, personally. Now if it's rectangular and some panels are considerably larger, you could think about bracing those.
All that said, I just built a box that's internally 26" x 15" x 11.25". The large panels (which are not the baffle) are 29" x 18" and are 5/16" (!!!!) plywood. I planned to brace it, but thought I would try it without bracing first. I am amazed at how little flex/vibration there is, so much so that I now don't plan to add any bracing at all. All the other sides are 1.5" thick though, made out of 2 x 12 lumber - I don't recommend that, but wanted to try it once just for fun and it came out well enough.