general building advice?

[spmachina77]

k, i've got a few car sub boxes, and a large home theater box under my belt, but and now doing the rs tmww towers and wmtw center channel.
Most of what i know about woodworking i have taught myself so my experience is fairly limited, but I have a few random questions before I start this project.


1) when clueing my box together, i've usually used screws to hold the box in place while it dries. I've also used thin nails (from a nail gun), which i find easier.
But I just got some clamps which I think will help me out. As long as I tighten the clamps on the box while it dries, would i be fine to skip the screws?(i've always been told its the glue that holds the box together, the screws are to hold it in place while the glue dries.

2) I have never used damping material inside a box, so am a little confused on what is ideal to use, and where it is to be placed. Should I just use eggcrate foam, or is fiberglass better? And do I pretty much want a layer about 1.5-2 inches around the inside of my box (top, bottom, sides and back)?
Can this go over the crossover, or should I just cut around it?

3) on crossover placement, how do you guys mount them. I'm assuming that they would need to be removable incase you needed to modify the crossover. So are they just screwed down or what??

4) and since the mid is seperated from the woofers, would you normally, just drill a hole through it for the wire to run through, and then seal it up with silicone?

[dynamowhum]

I'll address 1,3 and 4. As to #1 you are a lot better off just using clamps. I have now built 7 boxes and used nothing but clamps. The biggest was 16X24X30. So you can see you don't need screws at all. But you do need clamps. #3 There are plenty of pictures in the master thread that show crossover placement. You can find them if you do a search there. #4 That is what I did, I left some extra wire in that section in case I needed to later cut off the ends for some reason. Hope this helps, I built the CC version and the master thread can be very confusing so you might want to read it a couple of times. Cheers

[spmachina77]

3) let me restate this, I understand the actual placement, but am just unsure how it is actually mounted (held in place) so that it doesn't acutally move around.

[chasw98]

3) let me restate this, I understand the actual placement, but am just unsure how it is actually mounted (held in place) so that it doesn't acutally move around.

If you look at the pictures of my XO in the thread I went overboard. I used 2 strips of aluminum that I drilled and tapped to hold a 6-32 insert so to speak. The crossover would then screw to the insert. I then took #8 screws and screwed the aluminum "plates" down to the wood inside the cabinet. That way if I ever needed to remove them (and I did) I could easily unscrew and remount if needed and not worry about messing up the MDF inside and have loose screw holes. I think most people just screw right down to the MDF and call it good after testing. If really concerned put a dab of epoxy on the screw threads.

Chuck

[wkhanna]

Has anyone tried using velcro?
I was considering gluing some on the back of the XO board and the other sheet on the interior cabinet wall.

[dynamowhum]

Wkhanna some people do use velcro. SP I am sorry I misunderstood your your posting on that. I used these studs that where threaded for wood on one end and machine screw threaded on the other. I then drilled holes and double nutted the studs to use a nut driver and drove them into the box. Then taking the top nut off I placed my boards on top and secured them with the nut on top. Kind of like how computer boards are mounted. Chasw98 is a clean way of installing as well. You can learn a lot by reading his posts for sure. Cheers.

[ThomasW]

I use the 'marine' grade or the 'industrial' grade Velco. Then augment the Velcro's glue with hot glue.

[spmachina77]

velcro seems like the easiest way, and would work great, cause you could easily remove them if needed.

[Rolex]

I just finished building some floor standing cabinets. While clamps and glue alone will work, I find that screws and glue is faster, as you don't have to wait for setup time. THen I filled the screw heads with auto body filler and it gives a nice smooth finish. Because body filler set up time will vary depending on the amount of hardener you use, that process doesn't take long either. I will be using only clamps on the front baffle though, because I will be shaping the front edge and don't want screw heads in the way.

[BobEllis]

Give the body filler at least a few days to fully cure before final sanding - I've had it shink a bit after sanding too soon. Knock it down close if you have it really thick but leave a bit for final smoothing after full cure.

[morbo]

If you want to clamp buy LOTS of clamps. Doing a large box with 4 clamps will not work well... it will seem ok for the first few joints, but when it comes time to glue baffles/backs on, you'll wish you had more. Also, if your joinery is less than perfect, consider using a polyurethane glue, it expands to fill gaps.

For damping use fiberglass, I'm pretty sure eggcrate foam does very little, especially at lower frequncies.

I like to mount the XO externally in its own box, velcroed to the back. Makes for easy tweaking down the line, and supposedly isolates the components from cabinet vibration/driver backwave.

[wildfire99]

I always have frustrations with pieces sliding around with only clamps. I prefer brads. However, I did pick up a bunch of cheap corner clamps, and I now love those things. No worries, especially with larger boxes. Pick up a set of 8 for less than $30 (but treat them nicely, the cheapies break easily).

As much as I hate filling brad holes and going through one with roundover bits sometimes, I can't imagine the effort required to pre-drill, countersink, and fill screw holes.

I totally agree with morbo... the last time I bought clamps (many years ago) I just gave Harbor Freight a $100 bill and got enough to do everything I ever wanted. And I keep a bottle of Gorilla Glue around just in case... and it does get used from time to time.

Still the easiest thing is to just cut everything you can oversized, glue and tack it down, and just go over it with e flush-trim bit as soon as it's dry. No muss, no fuss, no precision alignments.

As for x-overs, I usually glue them down if they don't have their own cubbyhole... but I definately am going the velcro route next time. That sounds like a great idea.

[PMazz]

I always have frustrations with pieces sliding around with only clamps.

An old trick to prevent movement while clamping is to buy some 1/8" dowel and while you glue up, hold the pieces where you want them, drill an 1/8" hole, tap a piece of dowel into it and break it off. Repeat as necessary.

Pete

[technimac]

I agree that glued and clamped panels often want to "skate". The problem i have with screws, brads, dowels and nails is that they often cause MDF to split or have to be removed when rounding-over the edge or when finishing. In addition, before using fasteners (except brads), pilot holes need to be drilled and these don't always prevent the MDF from splitting.

I find that keeping panels in place is much easier when the inside edges of one panel to be joined are rabbetted. Using my BT3100 saw with a feather-board to make accurate rabbets is easy. Even a 1/8" deep rabbet is enough to keep a clamped panel locked-in-place. Fasteners aren't needed because the panel is clamped into the inside corner of the rabbet, so this saves on time later because there are no holes to fill and finish. Finally, rabbets make it easier to keep the dimensions of the glued-up cabinets very accurate.

I cut rabbets slightly larger than the thickness of the panel, so the side with the rabbet overhangs the other by about 1/32" after glue-up. Then a flush-trim router bit is used to clean up any glue squeeze-out (and the slight overhang), leaving a clean and true corner that's ready to finish or be rounded-over.

This photo shows all the components for a Modula MT ready to be glued and clamped.



Hope this helps,
Cheers, Bruce