Glue only joints

[scstill]

I have been making some speaker cabinets some with just glue
Is this asking for trouble?
Watching some youtube videos I find that some cabinet guys say glue is enough
My joints have been tight mitered with a inside cleat like the picture.
Full Titebond orig glue coverage
I suppose I could add some brads to the inside cleat for reinforcement.
Same for the baffle cleat, only glue.

The pics are in pine with 3 BLO finish

[mresistor]

I would say no..  good quality wood glue is stronger than the wood. The joints have to be closely fitted together and a butt joint needs additional support.  It appears you have reinforced with glued in blocks in the corner which adds additional strength to the joint.  I usually add hardwood dowels to the joint if there is going to be appreciable weight to the cabinet and it's contents and is going to be lifted, such as a combo amplifier that is going to be transported.

[shooter]

agreed, a good glue joint will not break, that said, speaker cabs are subjected to some pretty large "forces" depending on open/closed back, since you have open back the pressures can escape rather than being dissipated in the wood/joints.


been using TiteBond for years, I like the TiteBond 3 better than original but mostly for moisture reasons, not strength

[scstill]

good timing I need to buy more glue will try TB3

[mresistor]

The front baffle and back will add additional strength to the cabinet.

[scstill]

all my backs are open because to me it sounds fuller in my room.
on stage (which is rare for me) there is more volume but I still like it.
Some of my open backs are full panel with cutouts

[mresistor]

I made a 2x12 speaker cab many many moons ago, like 15-20 years ago, out of 3/4" plywood with reinforced butt joints and it's still thumping along just fine. It's open back but has two upper and lower panels on the back like a 60's Fender amp and it's covered in black tolex with Peavey black grill cloth.  There is no glued-in blocking in the inside corners so I'm pretty sure I used birch dowels for the reinforcement. This was back when plywood was higher quality.

[acheld]

Well I'm going to disagree a bit.

Glued butt joints should stand up well if you are not traveling.  No problem.   

The minute you take stuff out for a gig, the stress on the joints will go up exponentially.   I'm not sayin' they will fail immediately, but the odds are that they will fail over the long run.   These amps are heavy and all it takes is a little slip, and there you go. 

It's fairly easy to strengthen any joint with dowels, or even pocket screws.    Mitered joints -- such as the OP's -- can be beautifully strengthened with splines.

I agree that box and dovetail joints are way overkill.

Glued joint boxes are often used for drawers, usually strengthened by brad nails, and they work well in that application.  But I don't recall the last time I took a drawer to a gig, or just to a friend's house to play.

[scstill]

I love splines on mitered joints, especially if they contrast.

Was going to use on the joint in the picture but had already BLO'd it and thought that I might affect the finish.
I'm going to make a spline jig and build some splined mitered boxes...

I still could spline the Popl 210 and Popl 408 cause they are not yet finished
Maybe walnut spline in the popular cab

Have you seen the "Skeleton Spline" very impressive

[mountainhick]

Splines, biscuits, dowels, plugged screws, rabbet joint, fillets glued inside the corners, all can help

Epoxy with fillets also can be quite strong, but fillets may interfere with inside corner clearances

Oh, didn't notice the corner details (just woke up from medical procedure). The miter with all the additional glue surface from the corner block is quite sturdy.

[mresistor]

Pardon my ignorance but what is BLO'd?

[scstill]

Boiled Linseed Oil
I got the BLO term from others in this forum
was afraid that if I added splines then needed to sand might not get back to a uniform color

[G._Hoffman]

I have been making some speaker cabinets some with just glue
Is this asking for trouble?
Watching some youtube videos I find that some cabinet guys say glue is enough
My joints have been tight mitered with a inside cleat like the picture.
Full Titebond orig glue coverage
I suppose I could add some brads to the inside cleat for reinforcement.
Same for the baffle cleat, only glue.

The pics are in pine with 3 BLO finish

As long as you are doing a good job gluing in those cleats, it will hold.  They are in kinda a tough spot to clamp sufficiently, though.  What's your clamping strategy?
That said, some kind of proper joint would be stronger.

[G._Hoffman]

good quality wood glue is stronger than the wood.

This idea is really grossly misunderstood.  That is an extremely conditional statement which is all too often spread around as some kind of gospel truth.  I wouldn't advise trusting that idea without doing some pretty extensive reading on glue joints. 

[shooter]

In H.S. wood shop one of the 1st lessons was "proper glue joints"
everyone in class made a "test joint", the instructor would clamp it in a vise then hit it with a 8LB sledge hammer!
if it broke along the glue joint it was back to the drawing board til we all "passed" the "hammer test" 


 

[mresistor]

G Hoffman   the statement was meant considering the OPs wood is pine, a rather soft wood.

[scstill]

I didn't get a picture of the corner cleat clamp but I had at least one in each dimension
tight enough to get a uniform squeeze out
 Below an example.
Clamping. alignment and wiping squeeze is a royal pain
but the end result is satisfying

[G._Hoffman]

In H.S. wood shop one of the 1st lessons was "proper glue joints"
everyone in class made a "test joint", the instructor would clamp it in a vise then hit it with a 8LB sledge hammer!
if it broke along the glue joint it was back to the drawing board til we all "passed" the "hammer test" 

That is still only force from one direction, and only under fairly good conditions.  And yes, a good glue joint is great, but you really need to understand with more depth if you want to be designing woodworking projects so you can use the right joints for the right situations. 

[G._Hoffman]

G Hoffman   the statement was meant considering the OPs wood is pine, a rather soft wood.

Sure, but a good set of dovetails or finger joints aren't going to make the pine any stronger.

[scstill]

I've recently seen some videos to strengthen butt joints
    A chip out flap is chiseled open
    A counter sunk screw is inserted
    The Flap is glued down and sanded - invisible
Seems clever butt I just don't like the look of butt joints
unless tolexed butt then no need to hide

[rake]

You could build a routing jig and rout thru the corners with a 1/4" straight bit and then a dovetail bit.
You are routing at a 45 deg angle to the sides and basically creating a "locking joint!
Use a contrasting hardwood like walnut to make the dovetail splines that fit the routed grooves.
Use plenty of blue and drive them in. Let dry, trim & sand. They'll look sharp and really hold it all together!

[scstill]

You could build a routing jig and rout thru the corners with a 1/4" straight bit and then a dovetail bit.

Like the dovetail spline idea...

Why straight first? Couldn't you just go dovetail?

Also this would require a router table (which I don't yet have)
Could this be done with a palm router (Bosch Colt)

[acheld]

You could build a routing jig and rout thru the corners with a 1/4" straight bit and then a dovetail bit.

Like the dovetail spline idea...

Why straight first? Couldn't you just go dovetail?

Also this would require a router table (which I don't yet have)
Could this be done with a palm router (Bosch Colt)

I'm thinking this is what is meant:    Straight bit first to remove (or "hog out") the majority of the wood.   Don't do this in one pass as a general rule.   When you then use the dovetail bit there is less chance of chipping and burn out.

Router table not needed.   I think you could do it with a Colt if you took your time and were careful.   

To achieve a straight rout, you'd use a straight edge as a guide for your router.  I personally would use a track for a track saw.

I don't think this joint is suitable for building a box (ie, on the ends of the boards) -- it is best on the interior -- unless you just want to show off a dovetail.  Speaking from experience, do not try to make this type of joint real tight. Let the glue do its job. 

[scstill]

To achieve a straight rout, you'd use a straight edge as a guide for your router.  I personally would use a track for a track saw.

But this dove spline is being cut on a mitered corner,
Here is a clever DIY corner jig for a router (no router table needed) - might give it a try
Just use a dovetail bit (maybe with a pre hog out straight)

[mresistor]

Cool vid  but why is he using such wide splines?  A few carefully spaced narrower splines might be better.  Speaking of splines here is a interesting vid and splines start at 7:12 into it. The whole vid is interesting though.


 

eature=shared

For amp cabinets I also built a finger joint sled jig for the table saw and it worked amazing well.


Here's a vid about strength of various joints and hopefully it's not too controversial.

eature=shared

[scstill]

...why is he using such wide splines?

agree narrow splines at the kerf of the table saw would suffice, and be easiest
but the idea by Rake in #20 was to add a cool factor with dovetails (remember this idea is not a dovetail joint, rather a dovetail spline on a mitered joint)
the only way to do unusual splines is with a router jig like in the video. (or on a router table with 45deg jig)
I'm just starting out and could not envision a jig until I found that video.
In order to get the spline closer to the end I think the jig will need extensions.

Thanks for the strength video. Surprising.
Good to know that miter is very strong+ and splined miter is very strong++

[Willabe]

With solid wood, it's the long grain verses short/end grain that's the weak link in gluing up wood. You want to glue the long grain, not the end grain for strength.

And box joints, dovetail joints, give the joint much more glue surface and it's mostly long grain. This works for good plywood too, more surface area and you are getting some long grain, about 1/2 the area being glued.

Edit; More like 3/4's long grain.

The old Fender cabs had like 1/8" finger joints. So they had lots of surface area to glue. And Fender used hide glue, modern yellow wood glue would be stronger and you can get water proof yellow wood glue, better yet. 

[scstill]

Watch the strength video from mresistor #24 and let us know your opinion.
Seems to go against common joint thinking.

[acheld]

Here's a vid about strength of various joints and hopefully it's not too controversial.

Great video.   I am a believer in splines myself.

My only (minor) criticism of the video is his testing protocol, which is great for drawers, but does not replicate the failure mode of amplifier cabinets which is falling at an angle.

That said, there is really good information there. 

I was surprised by the strength of the miter joint.   I may try that, with spline reinforcements.

One point to make is that he used plain dowels for his dowel reinforcements -- and it appears that they were all glue starved in the post failure pics.   If you're going to cover your cabinet with Tolex or Alcantara, you'd use the ribbed dowels made for gluing.  Same failure for some of his splines -- they were glue starved.    Maybe the answer is a much looser fit to allow better glue coverage (OK for covered work, less so for finished wood).   

Bottom line is there is no one right answer.  You best joint is the one you know how to make and have the tools for.   

[scstill]

Does anyone have a great method for clamping miters?
I have been using strap claps with plastic corner alignment  "clips" that the strap runs through
Not the easiest to get perfect.

Strap shown clamping a box (finger) joint. Been using same technique on miter

[shooter]

I used to use "corner clamps"  about the same PITA factor as straps

[scstill]

There are some good corner clamps out there
But wouldn't you need 8 of these? two on each corner end for correct alignment

[shooter]

 
yep


I gave up on "fine carpentry" and went with "good enough for me"!


all my "box work" in now just glue n screw butt joints  If I want aesthetics, (seldom), I countersink the screw-holes and use dowels pins to hide the screws

[Willabe]

Watch the strength video from mresistor #24 and let us know your opinion.
Seems to go against common joint thinking.

I don't think I believe it.

With pine, if the glue joint is done correctly, the wood should tear before the glue joint lets go.

So, all the joints were the glue let go were not done correctly, glue starved, not clamped correctly, etc.

You have to watch what wood your using too. Pine is so soft that when you put the glue on, it absorbs the water from the glue and the pine swells. Now the joint that you cut and dry fitted that seemed just right is now too tight. So when you put the 2 together they push out the glue. The joint is now glue starved.        

[Willabe]

Gluing up box cabs rattles my nerves! 

Trying to get the glue brushed onto all the pieces fast enough before the glue starts to tack up then you can't get the pieces to go together AND get the clamps on and square up the cab!              

The last cab making I did I was using the long open time Tight Bond glue, III, 20 minutes? Still wasn't open long enough for me.     

[scstill]

Gluing up box cabs rattles my nerves!
Trying to get the glue brushed onto all the pieces fast enough before the glue starts to tack up then you can't get the pieces to go together AND get the clamps on and square up the cab!   

That's me too...
trying to get everything right before the glue sets
then I'll find one is off just a little usually in the square
with tolex or grill cloth the gaps get filled, but if wood those off gaps haunt me...
my latest required a small shim on the cleat to square it up

[shooter]

 
i just use a hand held belt sander with 40 grit, squares up those pesky "edges" just fine 

[Willabe]

i just use a hand held belt sander with 40 grit, squares up those pesky "edges" just fine 

   

[jjasilli]

I agree with acheld.  Posts are not specifying what videos they watched: carpentry; cabinetry; guitar speaker cabs??? Furniture cabinets or speaker cabs that just sit around the house  may do fine.  But guitar speaker cabs may be subject to the physical stress of transport, and possible temperature extremes -- which can wreak havoc with glue joints.  Not to mention that mitered cuts are partially end grain -to- end grain contact. 

[Willabe]

Not to mention that mitered cuts are partially end grain -to- end grain contact.

With solid wood, it's the long grain verses short/end grain that's the weak link in gluing up wood. You want to glue the long grain, not the end grain for strength.

And box joints, dovetail joints, give the joint much more glue surface and it's mostly long grain. This works for good plywood too, more surface area and you are getting some long grain, about 1/2 the area being glued.

Edit; more like 3/4 long grain.

The old Fender cabs had like 1/8" finger joints. So they had lots of surface area to glue. And Fender used hide glue, modern yellow wood glue would be stronger and you can get water proof yellow wood glue, better yet.

[TIMBO]

Hey guys, I really don't think there is a right or wrong way the make a box.
For me it's more about what tools I have available to construct it.
For me the good old BUTT joint has never let me down.
The reason I use the BUTT joint is I don't have the luxury of room to have fancy machinery, so I do everything with a 8" power saw.
This limits me to the butt joint being the best joint I can achieve, as well as it is quick and simple.
As for strength it's not that great, but can be reinforced with internal cleats, dowels and nails.
As a apprentice carpenter over 40 years ago I made a truck load of ply boxes for various storage items.
The choice of joint was the lap joint (rebate joint)as instructed by the 100 year old tradesman (hey I was only 16 he looked old) I was working with.
As part of my carpentry apprenticeship I did cabinetmaking which has been a great contributor to be able to construct the amps.
The lap joint is easily done on a table saw (which I don't have) and I believe this IS the best joint to use.
This is only my opinion

[shooter]

as instructed by the 100 year old tradesman (hey I was only 16 he looked old)

and now we are the 100 year old's, passing on tidbits to the 12 year old's


 

[G._Hoffman]

The lap joint is easily done on a table saw (which I don't have) and I believe this IS the best joint to use.
This is only my opinion

Depends a lot on the material.  Lap joints are very good for plywood and great for MDF, but are pretty pour for solid woods.  Finger joints are very good for plywood or solid wood, but awful for MDF.  Dovetails are great for solid wood, pretty good for plywood, and an absolute disaster for MDF.  I wouldn't want to go with butt joints unless I was reinforcing them with blocking, brackets, or maybe splines.  Or you could add biscuits with just a router and the right bit, which would make a huge difference.