Butt joints and brad nails for glue-up question

[sebna]

I am looking to build sealed subwoofer cabinets out of 18 or 22mm Plywood using butt joints.

What would be optimal brad nails length for glueing up purposes?

For all 18mm ply build? - 1) face to edge connection and 2) double skin face (baffle) to single skin edge connection 3) just double skin baffle.

And same questions if it would be all 22mm ply build.

When doing face to edge for butt joints - should I shoot nails at small angle to go across layers of edge of ply or can I go at 90' angle without worrying about splitting edge of 18 / 22mm ply wood?

Thanks

 

[onocoffee]

I haven't used 18ga brads but I think you can see the heads. You might consider a 23ga pin nailer. These can be had in lengths up to 1 3/8" and the pin nails don't have heads and are pretty much invisible because of the lack of a head and the thinness of the fastener.

And the guns can range from the very affordable $28 Banks from Harbor Freight to models like the Grex 635 or Senco.

 

[Packard]

When I want to add trim and not leave any holes to fill, I drive short (3/4”) wire brads to the unassembled joint using a brad pusher. I then trim the heads off the brads leaving about 1/4” of brad proud of the surface.

I then apply the glue and position the boards. The brads keep things from sliding around. They don’t hold them in position. A bar clamp does the work of driving the joint closed and holding it while the glue dries.

Brad pushers are very old technology, cheap and still available. It is ideal for this application and probably costs less than $10.00. I’ll take a look.

Addendum: Still around $10.00. All mine have been the magnetic variety. Apparently both magnetic and non-magnetic are available. Buy ready made brads. The YouTube videos show cutting apart brad gun nails. Those nails are too soft and will bend too easily. But ready made in the size you need. They will also drive easier because they have a real nail point.

I am going to visit my niece for a few days later this morning. If this post is not clear, I will try to illustrate it with some photos when I get home.

More info: https://www.google.com/search?q=great neck tools brad pusher&ie=utf-8&oe=utf-8&client=firefox-b-1-m

 

[jeffinsgf]

Without a mechanical joint (rabbet shoulder or added bracing), I wouldn't rely on either 18 or 23 gauge fasteners.

 

[Sparktrician]

I'd also suggest that you look at using lock miter joints all around, like a Whiteside 3362 - https://www.amazon.com/Whiteside-Router-Bits-3362-45-Degree/dp/B000K2G56Q. Yes, they're a bit of a pain to get set up just right in your router table, but when you dial it in just right, the joint is strong and stable using only a good glue, like Titebond 3.

 

[Vondawg]

Lots of vibration with a subwoofer inclosure

 

[Packard]

Miter joints on 3/4” plywood will be stronger—with 1/2” to 1/2” face grain glue area. Add a 3/4” x 3/4” gusset along the joints and you have a very substantial joint that is ready for finish.

No edge banding required.

 

[tjbnwi]

I'd also suggest that you look at using lock miter joints all around, like a Whiteside 3362 - https://www.amazon.com/Whiteside-Router-Bits-3362-45-Degree/dp/B000K2G56Q. Yes, they're a bit of a pain to get set up just right in your router table, but when you dial it in just right, the joint is strong and stable using only a good glue, like Titebond 3.

You can purchase the Infinity set that comes with magnetic set up jigs, makes quick work of setting the bits up.

Infinity Tools 1/2" Shank 4-Pc. Master Lock-Miter Bit & Setup Jig Pack

4-Pc. Master Lock-Miter Bit & Setup Jig Package #html-body [data-pb-style=YD2S1U7]{justify-content:flex-start;display:flex;flex-direction:column;background-position:left top;background-size:cover;background-repeat:no-repeat;background-attachment:scroll}Cr

infinitytools.com

75%+ of our builds have a lock miter in it somewhere. We use a Freeborn head on the shaper.

Tom

 

[Packard]

I have a lock miter router bit set. Set up was arduous. I only used it that one time.

I cut regi;ar miters on the table saw, tape the pieces to be joined, glue and fold. It is quick, easy and offers decent glue area for plywood. I learned that B.I. (before Internet) from Fine Woodworking magazine.

 

[onocoffee]

Miter joints on 3/4” plywood will be stronger—with 1/2” to 1/2” face grain glue area. Add a 3/4” x 3/4” gusset along the joints and you have a very substantial joint that is ready for finish.

No edge banding required.

Would you consider these miter joints stronger than using Dominos to connect the panels?

 

[Packard]

Would you consider these miter joints stronger than using Dominos to connect the panels?

Probably not, I am in a parallel world of dowel construction and I use dowels for cabinet boxes. However with a glued in gusset, the mitered joint on plywood is really quite strong.

I knew a custom speaker builder in the late 1960s and he used MDF and glue only. The speakers were covered with a fabric instead of a finish. So, I suspect mitered joints, glued and folded are up to the task of speaker construction. It certainly simplifies finishing the edges.

In any case, mitered would certainly be stronger than butted joints that were pinned and glued. I’ve had plywood where the top lamination delaminated. So a butted joint like that is only as strong as the top lamination.

I made a rolling coffee table about 25 years ago using this technique and it is still solid. It gets more physical usage than a speaker.

I would note that the speakers builder said that MDF was a superior material for speaker building—something to do with the sound quality of the MDF.

 

[Packard]

Confirming that MDF is preferred for speaker boxes: https://www.google.com/search?q=mdf...er box&ie=utf-8&oe=utf-8&client=firefox-b-1-m