Originally Posted by mhutchins (2)
I used brads and Titebond II for most seams. I usually unclamped once the brads were in place so I could move on to the next panel. Unclamping before the glue sets or dries may be heresy to a real woodwooker, but I don't know any better. Wipe the excess glue off with a damp rag before it begins to dry. Make as few precision cuts as possible. A precision cut means the cut surfaces will determine the distance between two panels or must match the distance between two panels (a 1/16" error will result in misalignment or a gap); avoid them when you can. Plan the build so that you can use a flush trim bit in a router to square up the edges (the photo shows a joint after trimming with a flush trim bit and then cut with a round-over bit).(3 & 4)
I placed almost all of my braces with both sides and the base in position with only the top panel removed. I placed two of the top braces in position to help stabilize the sides before I placed the rest of the bracing in place. I always do things the hard way, so I'm probably the wrong guy to ask about making a build process more efficient. (1)
1. Glue* sides to bottom panel (for this discussion, the slot is on the bottom) use a large carpenter's square ot two to hold the panels perpendicular. The side panels sit atop the bottom panel (LTD's later design may differ hear, but this is how I did it).
2. Precision cut the slot panel for a good fit between the side panels. Cut the slot panel length to the desired port length. Perform whatever end treatment you desire for the internal port aperture.
3. Precision cut the slot braces to length, and height if needed. These should extend from the very front edge of the bottom panel to within 13/16" of the rear edge of the bottom panel.
4. Glue slot braces to bottom panel aligning the slot brace end with the bottom panel's forward edge (back end of slot braces shown, roundovers are optional. They braces were accidently cut shorter than desired...)
Now for the bracing: Decide what you want to use for braces. Windowed panels require precision cuts for all 4 edges. For that reason, I chose to avoid them. The 1x4 lumber at HD was all crooked, warped and full of knots, so I chose 1x12 white pine, which was higher quality, and ripped the boards lengthwise to make my own 1x4 boards. You could use MDF, but that would be heavier, and I believe it would not be as rigid. Plywood would work well, and offers excellent strength to weight, but is more expensive than the pine. I reasoned that I could make strong, light braces with simple pine boards. I decided to use simple lap joints for their good bond strength and I could avoid making any precision cuts for the bracing, which I felt would reduce errors and frustration.
Vertical braces went from the top of the slot panel to almost the top of the enclosure. Horizontal(cross) braces went across the top and the slot panel, but were just short of the sides. The braces overlapped in the corners and were glued and held in place with clamps and brads, then unclamped. For the top horizontal braces, I placed a straight edge across the top of the enclosure, then held the brace against the straightedge and secured the brace to the two mating vertical braces. This prevented the top braces from sitting too high or too low when it came time to attach the top panel. The lengthwise braces do require a precision cut to length, but a slight error here will not effect the outward appearance of the enclosure and will not impair the function of the brace. Only the sides and top require lengthwise braces.
5. Dry fit the slot panel in position (optional) and cut the cross braces to length. Mark their position on the top of the slot panel. This spacing will determine the spacing for all of the other braces, so choose wisely!
6. Remove the slot panel and glue the cross braces to the slot panel.
7. Mask and paint slot braces, slot panel and bottom panel after slot brace/bottom panel assembly glue has dried. Use the same paint you intend to use for the exterior (unless you want a contrasting color for the port) for at least the first foot or two into the slot. The masking is to keep the paint off of the glue bond surfaces of the slot braces and the corresponding position on the slot panel and sides. Once the enclosure is assembled, you will be hard pressed to paint the interior of the slot.
8. Glue slot braces (with the previously attached bottom panel) to the slot panel (with previously attached cross braces). Use PL along the slot panel edges if there are gaps between the side panels and the slot panel, same with the cross braces.
9. Cut the rear panel to size. Remember that the rear panel will be recessed 1/16" from the ends of the abutting 4 panels (top, bottom , left, right) so you can flush trim the edges to make a nice corner later. However, this means that the end panel requires precision cuts to match all 4 panels. For this reason, I used PL and brads for the edge seams and glue and brads for the bonds with the cross braces. If you are using Handy Panels, the height will be fine, and all you need to do is trim the width of the panel to fit between the two side panels.
10. Cut the hole or holes for the speaker connectors you plan to use before gluing in the rear panel. Consider the bracing pattern and how this will impact alignment of these holes. You don't want them right over a brace!
11. Now you need to make the braces for the rear of the enclosure. A simple cross arrangement can be used or more elaborate multiple braces can be assembled. Remember to allow for a slight recess of the rear panel.
12. Add the rest of the lengthwise braces to the sides and top if you have not done so already. These will need to be staggered so you can drive the brads through each end.
13. Cut the front panels to size. I recommend plywood for both if you plan to flush mount or recess the driver, because the panel with the recess will be very thin (5/16") underneath the recess and the MDF will distort easily. If not recessed, then the front speaker baffle can be MDF and the rear speaker baffle can be plywood. I believe plywood gives better purchase for the screws and is less likely to strip than MDF alone. Some people apply a third internal layer for additional screw purchase, but this does not seem necessary if you use plywood. Using a router, create the recess groove if you plan to recess the speaker, then cut through the panel for the speaker cut out. You will need a circle cutting jig to do this if you plan to recess the driver. If you front mount or rear mount the driver, the speaker cutout can be made with a jig saw, but a router and circle jig will result in a more professional appearance. A plunge router is desirable, but a plain router can be used with a little creativity. Some people use T-Nuts or Hurricane Nuts or some other form of threaded insert for securing the driver to the speaker baffle. There are pros and cons and you need to decide for yourself.
14. The front lengthwise braces determine the recess of the front baffle and support the baffle in addition to bracing the front of the enclosure. If your vertical and horizontal braces are square to the front edges, then these front braces will just be two lengths. One length that abuts to the vertical braces and one length that abuts against the horizontal braces. You could probably save some time and headaches by making these 1/16" short and using PL where they affix to the other braces, but that is your call. By cutting them short, you have a bit of leeway to adjust the baffle end of the brace to ensure that the baffle panel makes good contact with all of the front braces and none of them are too high or too low. Alternatively, you could use PL between the front baffle and the front braces. Be sure these braces do not extend beyond the speaker cutout or they may interfere with the woofer and prevent installation later.
15. Glue the front panels to each other and allow the glue to set at least 30 min.
16. Add PL to all of the front supports and the 3 sides which will bond to the front baffle assembly, clamp in position and secure with brads.
17. If you are going to paint the interior, now is the time to do that. If you decide to paint the inside of the top panel as well, be sure to mask off all of the bond areas for the braces before you paint.
18. Now is a good time to add any acoustic damping materials to the inside before you close out the enclosure. Although I added memory foam to most of the internal surfaces, this may have been unnecessary and may in fact decrease the functional internal volume somewhat. I plan to add a pillow or three to the inside of the enclosure to damp some of the internal reflections and port resonance. A few staples to the internal braces would secure the pillows in position and keep them from blocking the port or rubbing against the subwoofer.
19. Add PL to all of the upper braces, sides and both ends of the enclosure. With an assistant, lower the top panel into position. Adjust the top panel so all of its edges overhang slightly and secure with brads. Use weights, claps or both to compress the PL before shooting the brads in place.
20. Take a well deserved break!!
21. Add standoffs for the speaker grille if you intend to use a grille.
22. Flush trim all of the edges and begin the desired finishing process.
* Whenever I say glue, I mean Titebond II
and Brads. Whenever I say PL, I mean Loctite ProLine 3X Premium Polyurethane Construction Adhesive
and brads. Although the squeeze-out from Titebond should be cleaned up with a damp rag before it hardens, the squeeze-out from PL 3x should not be touched until it has dried for 6-12 hours. Then, use a sharp chisel or utility knife and cut the hard, but not fully cured, squeeze-out away from the joint. These steps will give you nice clean glue joints with a good appearance. All braces and panels receive glue or PL along all bonding surfaces as well as brads.
Edit 10-27-13: Links added for Titebond II and PL 3X, additional sequence added, photos added.