[bprochford]

Hi,
I'm thinking of building a pair of N3s and an SW-12 sub. When building these cabinets, are there benefits in using dado joints for the internal bracing, and rabbet joints for the outer cabinet construction?  Or are butt and edge joints sufficient in the build? Obviously, panel and brace dimensions would need to be adjusted to account for dados and rabbets, but aside from that, are there any other things to look out for?
There are so many talented builders in this circle, I'm hoping someone can help me out.
Thanks,Brad

[NeilT]

Hi Brad,
The simple butt and edge joints are more than strong enough for this application.
I have not seen anyone on AC that goes beyond this type of joinery in speaker building.
Have fun and please post pics of your build.
Keep asking questions. There are several talented builders who are more than willing to help out.
Ron has built several N3's and is a great "go to" guy

Neil

[Danny Richie]

I have busted up old cabinets and typically the glued butt joint is stronger than any other part of the cabinet.

[bprochford]

Neil and Danny,
Thanks so much for responding so quickly.  Glad to know that a more basic building technique will be more than sufficient.  Once I get the parts and build going, I'll be sure to post photos throughout the process.
Best,Brad

[Peter J]

Hi,
I'm thinking of building a pair of N3s and an SW-12 sub. When building these cabinets, are there benefits in using dado joints for the internal bracing, and rabbet joints for the outer cabinet construction?  Or are butt and edge joints sufficient in the build? Obviously, panel and brace dimensions would need to be adjusted to account for dados and rabbets, but aside from that, are there any other things to look out for?
There are so many talented builders in this circle, I'm hoping someone can help me out.
Thanks,Brad

If you are following my thead on sub cabinet design, you might notice that I used dados and rabbets on the "core" box...primarlily for ease of alignment. It does theoretically add strength, but I think we'd be splitting hairs in this instance.

In retrospect, I'd use butt joints and biscuits if I did it again. I will tell you that  I often follow the train of thought that if it's worth building, it's worth overbuilding. The belt and suspenders method and maybe a little more.

Making the simple complex is often my way on my own projects...for better or worse.

[Ron]

I agree with Neil and Danny that simple butt joints are plenty strong. I have been building speaker cabinets for years using butt joints and never had any problems with them.

[django11]

Especially with mdf.  I'm not sure how a dado or rabbet would give any extra strength, mdf is just dust and glue anyway.  Solid wood is totally different because you are gluing face grain to end grain which is due to fail and would require mechanical fasteners or fancy joinery.  Plywood would be halfway in between because you are gluing face grain to a mix of grains (the plies are face and end grain)...

[aharami]

Im am going to start building cabinets for a pair of N3, and an N3S soon.  What is the best way to go about assembling the cabinet once all the pieces are cut out and rounded over as needed?  Lay one side down, start gluing and clamping the braces first, followed by the opposite side, then back, top, and bottom?  Is there a preferred method that makes things easier?

Also what glue is recommended for MDF?  Titebond ok?
Does reinforcing the butt joints by nailing with a compressed air finish nailer add any benefits?  Or do cabinet makers predrill and screw as an added reinforcement?

[django11]

White or yellow woodworking glue is good.  Personally, I would't think adding brads will add much strength however a few brads can make assembly easier.  Just to hold things together a bit for clamping.   18 gauge is good, I have a 23 gauge pin nailer I use for this.  I assemble in this order: top/bottom and sides first (the contour), then the  back and then braces.   YMMV

[Jazzman53]

I've built a quite a few speaker cabinets with butt joined MDF and yellow glue and never had a joint fail.  Biscuits would help align the pieces and keep them from skating, as they are wont to do when you glue and clamp them, but a glued butt joint in MDF is plenty strong without biscuits.  Another trick to prevent the pieces from skating is to drill and pin them together with wooden toothpicks--if you can find a drill bit that small (I keep a box of toothpicks around just for that purpose).  What you DON'T want to do is drive a screw into the edge of MDF, as that will split it every time.   

[Peter J]

Im am going to start building cabinets for a pair of N3, and an N3S soon.  What is the best way to go about assembling the cabinet once all the pieces are cut out and rounded over as needed?  Lay one side down, start gluing and clamping the braces first, followed by the opposite side, then back, top, and bottom?  Is there a preferred method that makes things easier?

Also what glue is recommended for MDF?  Titebond ok?
Does reinforcing the butt joints by nailing with a compressed air finish nailer add any benefits?  Or do cabinet makers predrill and screw as an added reinforcement?

FWIW, I'd wait till I had the cabinets built to do any router work, easier to clamp the boxes that way. Get the sides flushed after glue-up and then rout. As another poster pointed out, brads or pins may aid in alignment while gluing up, but ultimately don't add any appreciable strength in this application. It's also nice not to have to worry about running your router into some steel staples. I've seen people use countersunk screws, but can't see a good reason to do it in most cases.

As far as order of assembly, a logical plan is your best bet. If you're going to assemble the entire cabinet in one go, test fit everything, develop a game plan, and have what you need clamp wise close at hand. Glue waits for no man, although there are slow setting glues that may buy some assembly time  This is where having some way to hold things where you want them while assembling the remainder of the cabinet is nice. Biscuits, dowels, splines, pins...use what you've got.

Parts that fit well dry will make for a solid cabinet when glued up. Glue has little strength by itself, Best to avoid ill fitting joints that depend on glue to fill gaps and voids. Plain old Titebond red label will be plenty good, anything beyond it a waste.

[jdbrian]

Hi I built OB 7's earlier this year. You can see the build here.http://www.audiocircle.com/index.php?topic=78738.0

  I used butt joints and used biscuits and dowels to help align things. I used several glues. Weldbond is good if you are able to clamp quickly as it sets in a few minutes. I used a glue from Lee Valley that has some gap filling ability- GF 2000 I think it is called. Screws can be used to align panels and apply clamping pressure. This works well IME but you need to be careful to prevent splitting the MDF. You can use #6 screws (no larger) and you must pre drill pilot holes and not over tighten them. It is a lot of extra work but can work very well. Use lots of glue as MDF end grain will soak up a fair bit of glue.

Brian

[aharami]

Thanks everyone for the comments and ideas.  Im really excited to get started on my first build.  I've built only 1 subwoofer box before for my car a few years back and that was quite fun.  Now I have more experience and better tools, so hopefully this build will be a little easier

[Voncarlos]

Especially with mdf.  I'm not sure how a dado or rabbet would give any extra strength, mdf is just dust and glue anyway.  Solid wood is totally different because you are gluing face grain to end grain which is due to fail and would require mechanical fasteners or fancy joinery.  Plywood would be halfway in between because you are gluing face grain to a mix of grains (the plies are face and end grain)...

I think "django" is spot-on here, as well as several other posters.
You didn't say what material you were going to use for this construction.  Assuming MDF and a simple rectangular shape, glue and clamps are all that's needed. If you do use a fastener or biscuits, be careful that they don't telegraph through to your finish.
Here is a section of my build-thread on glue joints:

"Before answering your questions I should first tell you my thoughts and understandings about glue and glue bonds with regards to wood built items, sans the home construction industry. Other folks may have different opinions.

First off, one needs to understand that glue bonds on a molecular level, that is to say that the molecules of glue link to the molecules of wood. Thus, anything that gets between the surface molecules to be bonded, like dirt or oils from you fingers will hinder the bond. You often hear, "roughen up the surface first before gluing" with many people thinking that the glue will make little hooks into the roughened surface and bond better. This is false, glue alone has very little strength. What roughening up the surface does is expose a clean surface. So, the best glue bond one can make will be one that is perfectly mated together (I generally test my joints with a 1 to 2/1000th inch feeler gage), is absolutely clean (I wipe with denatured alcohol or acetone depending on the wood species) and is not starved for glue. So with that in mind, a strong build will be one that has proper glue bonds."

All the best with your build, it's a very rewarding experience to build something yourself.
Carlos

[NeilT]

Im am going to start building cabinets for a pair of N3, and an N3S soon.  What is the best way to go about assembling the cabinet once all the pieces are cut out and rounded over as needed?  Lay one side down, start gluing and clamping the braces first, followed by the opposite side, then back, top, and bottom?  Is there a preferred method that makes things easier?

Also what glue is recommended for MDF?  Titebond ok?
Does reinforcing the butt joints by nailing with a compressed air finish nailer add any benefits?  Or do cabinet makers predrill and screw as an added reinforcement?

Glue is very slippery, I used a 'pocket hole system', to hold some things in place while I clamped.
It helps, but is not necessary.

Here is a link to my build.
http://www.audiocircle.com/index.php?topic=82801.0

Good luck and have fun
Neil

[aharami]

Since this is my first build, I've been trying to read up on build procedures as much as possible.  I've been seeing people recommend applying the veneer before routing out the woofer/tweeter holes.  How essential is it to apply the veneer first?  The reason I ask is because I havent ordered the veneer yet and I'd like to start cutting the holes since it is getting cold out here in NJ.  How hard will it be to apply the veneer after the holes have already been cut out?  I'm not too worried about the woofers since the driver flange (?) will cover any mistakes I make flushing out the veneer with the holes.  But the recessed tweeter is some cause for concern because the veneer edge will be visible.  I'm planning on using paper backed veneer.

jdbrian, I noticed you used magnet cups on the rear of the baffle to hold the speaker grill in place.  What type of magnets did you use?  And if this question doesn't show my lack of knowledge, I don't know what will - will using magnets cause any sort of interference with the woofers?

[Danny Richie]

I veneer after the holes are cut. No problems.

[jdbrian]

jdbrian, I noticed you used magnet cups on the rear of the baffle to hold the speaker grill in place.  What type of magnets did you use?  And if this question doesn't show my lack of knowledge, I don't know what will - will using magnets cause any sort of interference with the woofers?

  I used magnets and cups from Lee Valley Tools, check their website. They sell sets of 4 where you get the matching magnet, cup and washer. You drill a hole in the baffle the size of the cup and deep enough to have it below the surface. Screw the cup into the baffle, pop in the magnet and then fill over it so you have a flat surface that will not telegraph through the veneer. Remember to make a diagram of the magnet posistions on the baffle. You then attach the washer on the grill and in my case I used the pads that Lee Valley also supplies to keep the washers from scratching the finish. I used the 1/2 in. size magnets. The grill stays in place well and is easy to remove. I installed them in the back of the baffle as well for rear grills but I have never gotten a chance to finish them. The magnets are not going to interfere with the woofers. They are too small and too far away from the voice coil to have any effects.

Good luck on your build!
Brian