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Stereo Integrity 18" D2 Curved build!

88K views 201 replies 35 participants last post by  jreb14 
#1 · (Edited)
Well, I suppose I will finally start posting my build that I've been working on for a while. I was planning to hold out until it is completed but the HTS site has started to give me "words of encouragement" at the top of the page every time I log on.
I had originally set out to build two sealed curved cabinets similar to the Funky Waves boxes but eventually decided that with the radius I had desired, the overall width of the boxes would be too big for my (shared) home theater space. So, I decided to turn the curves the other way; from up to down instead of side to side. Here's where I started in January when the woofers finally arrived!

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#2 ·
re: Stereo Integrity 18" D2 Curved build!

After letting the boxes collect dust for a couple of months, I was finally able to buy wood. I went through several design ideas scratched down in a notebook and then several more using the excellent free Cutlist program to utilize and plan out what I was going to do.
For Christmas in 2012, I got a Bosch 1617EVSPK plunge and fixed base router kit. It's my first router and since then it has become my most favorite tool!
What I am going for with these subs should be a little different than my current Polk PSW505! :hsd:

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First step: Finding a radius that I liked.
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#3 ·
re: Stereo Integrity 18" D2 Curved build!

It was during this process that I soon realized the front to back curved boxes I had originally imagined would not work in my current available sub location(s) since they would end up nearly 26 inches wide!
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Then I started thinking about doing the curved sides from top to bottom which I thought could be unique while also minimizing the overall width of the enclosures. After changing gears, I came up with this:
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You can see the shape of what will become the first inner baffle drawn out in pencil on the board.
 
#4 ·
re: Stereo Integrity 18" D2 Curved build!

I then had to figure out a way to set up a circle jig, or a half circle in this case, to accurately cut out the curve from the line I had drawn. Once the first curve was cut out, I had my first bigger challenge of figuring out how to do the exact same thing for the other edge. Through some experimentation, I found a way to set up the jig and get it cut. Once the first "master" inner baffle board was perfectly cut out, I used it as the template with a top bearing flush cut router bit to cut out the inner baffle board for the other sub as well as all 4 vertical braces and the two backs of the boxes.

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Next, I started thinking about my bracing design and how to cut the top and bottom board left and right edges of the boxes so that they mimic the angles of the curved sides. I have lots of great tools but my 20 year old Craftsman circular saw is not one of them. Even though I had made a decent straight edge guide for it for all of my big cuts, it was not easy getting it to cut and a very specific bevel angle.
Back section vertical brace design:

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#5 ·
re: Stereo Integrity 18" D2 Curved build!

Final back section vertical brace design:

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All four vertical braces:

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Skip ahead through all of the duplicating of the main parts for both boxes and I was finally starting the first gluing steps. Gluing the top and bottom to the back of the first box:

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I forgot to mention that the other new favorite tool that I got around Christmas was a brad nailer, again, my first one. This makes assembly infinitely easier!
 
#6 ·
re: Stereo Integrity 18" D2 Curved build!

This pic kind of shows how I set up a system to aid in replicating the first baffle boards to all of the vertical braces and backs. I would place my uncut square on top of the double stack of inner baffles, clamp it all down and then use a jig saw to trim off the excess. Next I would use a bottom bearing flush cutting router bit to copy the curve. It was reliable and fairly easy to set up and repeat.

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At this point, I am realizing that gluing the top and bottom to one of the backs weeks ago will prove to be a double edged sword. While it created a way to hold all of the bracing pieces in place while I designed and created them, it is going to make it difficult to glue in those brace assemblies during the final assembly phase. You'll see how this works as I go on. For the entire time during this build, I've had the glued top, bottom and back for one box setting face (baffle side) down onto one of the "master" inner baffles so that it would simulate the actual boundaries that I had to work with for the bracing design. It was great to be able to set in and constantly "dry fit" the pieces as I was perfecting them. Now I wish that I could take one wall off so that I can glue the whole bracing assemblies in there.
Here is where I started piecing together ideas for the bracing. You can see the two vertical braces, which are in a horizontal orientation because of how I have the box sitting as described, and also the first pieces of the x-braces that would eventually be placed going up and down and side to side in the back section of the box.
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As I said before, I had never used a router before in my life and the concept of routing out two pieces so that they "scissor" together was kind of intimidating. I created a simple jig so that I could accurately cut out the notch on each x-brace board.
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Which helped create these:

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Here is how things were starting to look with the woofer sitting in there to model it's eventual location. At this point, I was still pondering ideas for how I wanted the center X-Y braces to be around the magnet assembly.
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#7 ·
re: Stereo Integrity 18" D2 Curved build!

I don't have any photos of it by itself but what I ended up doing is creating a piece that mimics the profile of the driver's motor assembly and copying the angle of the basket where it meets the motor.

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Slowly coming together one dry fit at a time.

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I decided that I definitely wanted an X-Y around the motor so I copied the profile of the "full width" part that I made into two split pieces that would butt up against it.

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This week, I started to actually glue bracing pieces together and here is how two of the three level stack looks after some 1/4" radius round over bit action where applicable!

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#8 ·
re: Stereo Integrity 18" D2 Curved build!

I figured out how I wanted the final set of braces to look that will surround the driver and be mounted between the inner baffle and the first vertical brace. Like so:

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The neat part is that these four "posts" actually butt up to edges of the X-Y braces that protrude the hole in the center of that vertical brace. Kind of hard to describe but you can see it in one of these photos.

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Right now, I have glued these four posts to the middle bracing section and I'm getting ready to glue this assembly to the rear bracing assembly. After that, I'll be gluing the entire thing into the top-bottom-back assembly. Once those are done, I can attach the inner baffle. I am using 1/4" "tempered hardboard" (the dark brown stuff) for the curved sides. I'll be using four layers on each side equaling 1" thick sides (hopefully). Once the sides are on, I have two more 3/4" layers of MDF to attach as mid and outer baffles which I will route out so that the driver sits nice and flush while leaving lots of material to mount to. The eventual plan will be to veneer both boxes with cherry. Let me know what you think! I would not have come this far without all of you teaching me and inspiring me along the way! More updates to come.......:T
 
#14 ·
That is a very well thought out build :T and well executed. Nice work. I'm looking forward to seeing how you glue up the laminates, that is going to give you quite the beefy sidewalls! Though same as above ^^^ the pics aren't showing of your last update!
 
#15 ·
Thanks for the compliments! I think that I fixed the photos in the last post. For some reason, they didn't link properly when I posted them from my ipad last night.

I'm starting to get nervous about the sides. I really don't want to spend the time to make a bunch of curved cauls to use as a form on the outsides during glue-up but it many come to that. Where is that [free] Curvomatic when I need one?
 
#16 ·
From the limited number of curved side builds I've seen, one way to do it is with ratcheting tie-downs. I will have to search around and see if I can find a link to the build, but it was similar to what you are planning; the dark 1/4" panels and he glued them up one at a time.
 
#17 ·
That's my plan. I have 8 heavy duty ratcheting straps. I think I'll try using several 2x2's next to each other spanning the width of the curve and set on the outside of the hardboard for the straps to squeeze down on, if that makes sense.
 
#20 ·
I completed the bracing and got it glued into the 3 walled box yesterday. It was a pain to ensure I had a nice tight bond on what will be the top and bottom of the box where it meets the bracing because I was basically sliding my whole bracing assembly into a 3 sided u-shaped form. This meant that I had to slightly pull the top away from the bracing and squeeze glue in and then do the same thing for the bottom. I used a combination of Titebond II for all of the normal and easy to glue parts and PL Premium for these points where the bracing meets the top and bottom. I knew going into this that the fact I had to slip an assembly into a 3 sided U shape was going to be difficult but for this first box, having the top, bottom and back together really helped while I was designing and trying things. The second box should go together much easier because I'll install the bracing while the top, bottom and back are going together.
Final dry fit:

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I had to work quickly getting the bracing assembly all glued in and getting the glue drips cleaned up and seams smoothed out so I didn't take any photos of that process. Here is the inner baffle glue up to the rest of the box:

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#21 ·
I decided that since the inner baffle is going to have to "carry" a lot of weight and that since this is not a traditional square box that leaves 4 edges for the baffle to attach to, I would add some additional reinforcement after the glue-up. You can see I put two screws into the ends of each of the 4 small braces that go around the driver connecting the bracing assembly to the inner baffle.

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Slowly getting there!
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#23 ·
That's pretty much where I'm at since last night. I started to experiment with how the curved sides will go by using ratchet straps. Bending and attaching single 1/4" layers at a time should go fairly smoothly. I am thinking that I could even go two at a time but we'll see. I am going to come up with a system of 2x2's that are strung together and will lay over each curved panel for the straps to squeeze on; similar to the Curvomatic.
 
#24 ·
Looks good! I especially like the note reminding you where to put the driver. Once you get those sides on those screws will be essentially redundant, but hey belt and suspenders is the best way to go!

I'm sure you'll figure out what works best with gluing the sides, but it may not be advisable to do more than one at a time. If you do double up, I would double up on tie-downs (actually I would use every single one I could find!)

Nice router work btw, the bracing and everything looks really good :T
 
#27 ·
Thank you for the compliment! I didn't route the woofer hole yet because there will be two more layers of 3/4" MDF added to the baffle after the sides are installed. These layers will serve to cover the exposed edges of the side panels on the baffle side of the box and also give me some beefy material to flush mount into.
I don't think the photos show it clearly, but I've already drilled the pilot hole in the exact center on the inner baffle board. This will let me go ahead and route with a circle jig accurately once the sides are on.
In the meantime, I've started gluing up the bracing pieces for the second box which, like I mentioned before, should be much easier the second time around. :T
 
#26 ·
dtsdig, that looks awesome. Great original take on the (all too rare) curved cabinet design, and very nice work on the bracing. I like how you custom created each piece to follow the driver's motor. And I'm still a sucker for OCD things like rounding over the internal edges. Well done.
 
#28 ·
Owen, thanks for the compliments! I am somewhat OCD about those kinds of things as well and truth be told, I realized that I never rounded over the first vertical brace, the one with the single large hole routed in it, before I had already glued other bracing pieces to it! On the second box, this will be rounded over as well.
 
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