# Joint help.



## Sea Chief (29 Jun 2022)

Hi folks on here. This is my first thread so looking forward to any help, & thanks for any replies.

I've got a connundrum with jointing pine, an annoying facet plaguing me. I use a fingerjoint jig to rout say 9x 1/2" wide joints. Call it a 19"x 17"x 10" box. I then glue ( hand 'painting-on' each 3 inside rout faces of each finger) & clamp for a day. Router-trim off all 1/16th joint excesses. Sand. Shape edges with a 1/2" roundover bit. Final sand. All fairly standard. Then I brush on a contact glue to surface, also onto on the backing (like a fine cotton mesh) of a vinyl covering. Cure both until gone off, timed as as per instructions. Press on. 

What I have now is a nicely finished, smooth edged, covered box. Sometimes though, after a week or so, the 4 jointed edges.. become uneven. The joints show through. Maybe a 2mm H difference, in-out-in etc. So something has happened. But I just don't know what. It's 21mm pine, & the solidity remains ( no compromise here) just this annoying edge 'shift' of some kind.

Can anyone help? Thanks, Sea Chief.


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## Phill05 (29 Jun 2022)

Might help to do a test joint without the vinyl to see what is happening, sounds like the board is shrinking?


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## profchris (29 Jun 2022)

Simply, the water in the glue is swelling the wood a little. Over time, it shrinks back and changes shape.

If you shape the edges too early, then the wood will carry on moving afterwards, producing the effect you describe.

The solution is to wait longer before the final shaping - how long is hard to say, because each piece of wood reacts differently. Maybe make up a few test pieces and shape them at different intervals.

My guess would be that 48 hours should be enough, but no promises!


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## Sea Chief (29 Jun 2022)

Phill05 said:


> Might help to do a test joint without the vinyl to see what is happening, sounds like the board is shrinking?


Hi Phil,

well this, funnily enough, is what I had only just this morning ( after long protracted consideration) thought seems most plausible.

You see I only get a photo, sent from a customer, whose had the 'box' for a while. So I can't inspect. But only today looking at his photo, I counted the joints (knowing where my first 'IN' one was made)... & came to conclusion, that perhaps the side had -shrunk- as opposed to the top having "enlarged". I'm fairly sure now it's one of the two surfaces -diminishing- slightly.

Ok this is a step on. Gratefully, SC


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## Sea Chief (29 Jun 2022)

profchris said:


> Simply, the water in the glue is swelling the wood a little. Over time, it shrinks back and changes shape.
> 
> If you shape the edges too early, then the wood will carry on moving afterwards, producing the effect you describe.
> 
> ...



Hi profChris, well this is the alternative theory as to what is actually happening: & until today what I was thinking.

But if it seems like there is shrinking going on, as opposed to swelling, then it seems you'd be spot on.

Evidence shows - it seems to me- a shrinking of the side though, causing this offset. Which points away from looking at the glue as an added factor.

Yes tests.. are my next step. But tricky, as some I make do this, others don't. It's infuriating tbh: as I send each off in perfect shape ( of course).

Any other thoughts, ideas, anything at all.. really welcome folks.

Chris- many thanks, SC


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## Sea Chief (29 Jun 2022)

Here are my joints after glueing. Trim off excess with router ( I use the bottom edge of a 3/8" straight bit, with template, to "skim" along & trim along this excess), & roundover to do.

And an eg of a good 'box'. No issue. This one ( mine ) is the same pine as pic 1, same glues, no wait period after jointing or immediate edging, to covering. Quickest I've made as it was my own.

So you see there's this inconsistency... which is infuriating as I can't glean clear answers.


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## Sea Chief (29 Jun 2022)

And a typical eg of a troublesome one: from this photo sent to me, I counted joints along establishing the top seems to remain as is.. _& its the side that drops down._

But I cannot factor out of course, that it's not the -whole- top's thickness, that's moved 'upward' instead. IE 21mm to 23mm.

It is making me go insane, let alone the customer. Thanks, SC


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## Phill05 (29 Jun 2022)

If there is inconsistency a few question's to ask is something being stored in the box that could affect the wood? is the box finished inside?


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## Sea Chief (29 Jun 2022)

Phill05 said:


> If there is inconsistency a few question's to ask is something being stored in the box that could affect the wood? is the box finished inside?


Hi Phil, no.. nothing inside. Its an amp cabinet, but mostly empty in fact. It's definitely some way the wood is behaving irrespective of anything inside. For eg, the bottom of the wine coloured box Im told is the same as the top, & the amp (& speaker) is yet to be housed into it anyway.

Thanks, SC


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## Inspector (29 Jun 2022)

If the wood is at equilibrium in your environment (dry in your shop/home) it will change in your customers home if they have a different humidity than yours. Wood will always try to move as the moisture changes. If the boxes stay in your place there will be no movement unless you move. Your customer is in a dryer place than you have and the wood has lost moisture making the fingers show. You are down to putting a finish inside the speaker box or changing the material to something else, plywood/MDF, or change the joint you use so movement won't show. I would change the joint to splines or biscuits (keeping them to the inside corner because you are rounding them) and shellac/lacquer/varnish the inside and see if that's better.

Pete


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## Sea Chief (29 Jun 2022)

Hi 


Inspector said:


> If the wood is at equilibrium in your environment (dry in your shop/home) it will change in your customers home if they have a different humidity than yours. Wood will always try to move as the moisture changes. If the boxes stay in your place there will be no movement unless you move. Your customer is in a dryer place than you have and the wood has lost moisture making the fingers show. You are down to putting a finish inside the speaker box or changing the material to something else, plywood/MDF, or change the joint you use so movement won't show. I would change the joint to splines or biscuits (keeping them to the inside corner because you are rounding them) and shellac/lacquer/varnish the inside and see if that's better.
> 
> Pete


Hi Inspector Pete.

Understood, but for one thing- I have had one which remained here without anything fitted inside it, & showed an identical unevenness after a while.

One thing I've been thinking, is whether the pine choice is a factor. It seems possibly ( annoyingly inconclusive), that jointing glue laminate pine, results in a box less prone to this issue.

Another thing is whether using 1/4" joints instead might help. But alot of expense on jigs & router bases to try this idea, just to end up in the same boat.

Or could I apply something to the finished edge prior to covering, that'll "fix" the wood in place preventing it move-?


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## Fitzroy (29 Jun 2022)

I made a coffee table with box joints last year. At the time and for several months afterwards they were completely flush, after the first winter some of the joints now are proud of the surface sufficiently that I can catch them with a nail, say approx 0.1mm. If I were to sand them flush then I would fine them below the surface at somepoint as the wood moves with the seasons. Wood moves more in one grain direction than the other. Your 1mm movement does seem excessive for what looks like a 20mm thick board, mine is c.30+mm.

However as Inspector said with such a joint you will always get seasonal movement that will threaten to crack or disrupt the covering you have on your enclosure. Moving to MDF and/or a different joint should eliminate the problem. A lock mitre router approach may work and would be easier than the box joints.


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## Fitzroy (29 Jun 2022)

Sea Chief said:


> Or could I apply something to the finished edge prior to covering, that'll "fix" the wood in place preventing it move-?


No. If wood wants to move it will move. Furniture design needs to work with this movement rather than constrain it.


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## Inspector (29 Jun 2022)

You need to read up on wood movement more. You will find that it never stops moving. When I lived on the west coast my furniture moved a little seasonally. Moved here to a much dryer climate and it shrunk and the joints all loosened up and it still moves seasonally a little.

Trying a different wood may help, some having less than others. Here is a shrinkage calculator you can play with to see how much different species move. The Shrinkulator – WoodBin

Going to smaller finger joints are not going to change the wood movement only the spacing of the bumps. 

You can't fight the wood and prevent the movement. No amount of extra glue or different glue is going to hold it.

Pete


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## Phill05 (29 Jun 2022)

Yes I would agree you can't stop wood moving a change of timber looks like could be the best move, If the timber is not seen could it be replaced with ply more stable and you could still make the same joints.


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## TheUnicorn (29 Jun 2022)

as others have said, it seems like this is an innevitable trait of wood. if you are not keen on mdf or ply, which I can see would complicate the roundover, I wonder if you could use a covering with a bit more bounce (like adding underlay to carpet) that would compensate for (hide) the movement


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## Sea Chief (29 Jun 2022)

Inspector said:


> You need to read up on wood movement more. You will find that it never stops moving. When I lived on the west coast my furniture moved a little seasonally. Moved here to a much dryer climate and it shrunk and the joints all loosened up and it still moves seasonally a little.
> 
> Trying a different wood may help, some having less than others. Here is a shrinkage calculator you can play with to see how much different species move. The Shrinkulator – WoodBin
> 
> ...


Hi again Pete. Thing is, some cabinets buck the trend & are stable. I can't try a different wood because it's a requirement that these are made in pine, also fingerjointing & shaping edges of even 18mm ply is a nightmare re chipout. And the cost.. birch ply it would have to be, is massively costly. No alternative to the pine guage I use, hardwood?.. ridiculously costly.

So I'm really left still wondering why some do this, & some don't. Once they do this irritating trait, they then don't shift again too. So I can't see any evidence of them changing at all, say after a month from made.

The only glimmer of hop, it seems, is the glue laminate pine boards. These -seem- to have a much lesser habit of doing this shift. Now the reason thoug? It can only be the addition of glue, acting like 'support struts' say 5x across a 10" board. I'm only throwing ideas out here tho. But based upon logic nevertheless.

Thanks, SC


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## Sea Chief (29 Jun 2022)

Phill05 said:


> Yes I would agree you can't stop wood moving a change of timber looks like could be the best move, If the timber is not seen could it be replaced with ply more stable and you could still make the same joints.



Hi Phil, thanks but unfortunately I can't change woods.


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## Sea Chief (29 Jun 2022)

TheUnicorn said:


> as others have said, it seems like this is an innevitable trait of wood. if you are not keen on mdf or ply, which I can see would complicate the roundover, I wonder if you could use a covering with a bit more bounce (like adding underlay to carpet) that would compensate for (hide) the movement


I agree it's a trait of wood, but disagree it's innevitable: from most of the cabinets I've made & those bought even decades old, they just do not & have not changed. Even changing hands many times over decades. All fingerjointed pine, all the same thickness, all covered by a very similar cotton-backed vinyl. Oldies used hyde glue for the covering but I don't think this covering-glue is the cause, whichever it may have been.. or -all- my cabinets would show this trait.

So there is a way to do this, with 21mm pine, or say 3/4", for a stable box.. it's just knowing how. But I guess I'm on my own to figure it out. SC


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## TheUnicorn (29 Jun 2022)

Sea Chief said:


> I agree it's a trait of wood, but disagree it's innevitable: from most of the cabinets I've made & those bought even decades old, they just do not & have not changed. Even changing hands many times over decades. All fingerjointed pine, all the same thickness, all covered by a very similar cotton-backed vinyl. Oldies used hyde glue for the covering but I don't think this covering-glue is the cause, whichever it may have been.. or -all- my cabinets would show this trait.
> 
> So there is a way to do this, with 21mm pine, or say 3/4", for a stable box.. it's just knowing how. But I guess I'm on my own to figure it out. SC


maybe you need to have a look at the wood you are using then, in terms of how it is stored, sourced, seasoned, run a moisture meter over etc. Also maybe a sealing coat on the inside of the cabinet might help to minimise movement. I'd do a whole bunch of test pieces and see what makes things better worse


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## Scruples (30 Jun 2022)

Phill05 said:


> Yes I would agree you can't stop wood moving a change of timber looks like could be the best move, If the timber is not seen could it be replaced with ply more stable and you could still make the same joints.


A hard wood would move less?


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## sawtooth-9 (30 Jun 2022)

Pine will always have a movement problem - it's a soft porous wood that can absorb and release moisture. This is particularly so because of the open pore structure and pine oils are not compatible with water.
I have done several very fine finger joints ( 4 mm ) in relatively soft woods ( well seasoned ).
I always cut the finger at least 2 mm deeper than the base wood - and ONLY use epoxy glue. Why ? - NO moisture introduced into the join and the joint strength is much greater.
Once the epoxy is cured, just sand off the excess.
Particularly with soft woods, the stability of the final product will depend on sealing out moisture - either by varnish, oils, or waxing


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## MorrisWoodman12 (30 Jun 2022)

Sea Chief said:


> And a typical eg of a troublesome one: from this photo sent to me, I counted joints along establishing the top seems to remain as is.. _& its the side that drops down._
> 
> But I cannot factor out of course, that it's not the -whole- top's thickness, that's moved 'upward' instead. IE 21mm to 23mm.
> 
> It is making me go insane, let alone the customer. Thanks, SC


Just an observation but in your last photo it looks like the side piece has shrunk BUT the top piece hasn't, well at l can't see corresponding shrinkage marks on the side - bit difficult to be sure though. If that is the case and it is wood sourced and cut at the same time is there a clue there or is it just another bit of inconsistency? I assume btw that the very definite line along the joint and across the box is between two pieces of vinyl.


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## Sea Chief (30 Jun 2022)

TheUnicorn said:


> maybe you need to have a look at the wood you are using then, in terms of how it is stored, sourced, seasoned, run a moisture meter over etc. Also maybe a sealing coat on the inside of the cabinet might help to minimise movement. I'd do a whole bunch of test pieces and see what makes things better worse


Hi Unicorn,

good points. I agree this is sort of my avenue of thought, exhausting other avenues really. I might be inadvertently aiding the shrinking, somehow, sometimes. Its a costly timber now @£12 a metre so not gonna be a cheap set of tests.

Appreciate all the replies chaps, anymore thoughts on the glue laminate pine ( this is 5x 2" widths of 3/4" thickness pine, strongly glue together making a "10 x 1 " board.. the glue seems stronger than the wood so the structural box is ticked ok).

Thanks y'all, SC


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## Sea Chief (30 Jun 2022)

sawtooth-9 said:


> Pine will always have a movement problem - it's a soft porous wood that can absorb and release moisture. This is particularly so because of the open pore structure and pine oils are not compatible with water.
> I have done several very fine finger joints ( 4 mm ) in relatively soft woods ( well seasoned ).
> I always cut the finger at least 2 mm deeper than the base wood - and ONLY use epoxy glue. Why ? - NO moisture introduced into the join and the joint strength is much greater.
> Once the epoxy is cured, just sand off the excess.
> Particularly with soft woods, the stability of the final product will depend on sealing out moisture - either by varnish, oils, or waxing



I might try changing my glue to Titebond, from the reviews (I use a basic everbuild 501 currently ) but epoxy I think isn't that conjusive to doing so many 1/2" joints (25-30) on each box. 

And using less of it maybe too.. I do scrape off a lot of excess as a habit, just being super sure I've covered my bases, & as it's not costly stuff.

Stillthe fact remains -some- boxes, just don't do this trait ( bucng the notion that all softwoods simply WILL do this: it has to be concluded therefore that shifting is -not- a certainty after all you see). If only I could establish why this is.. I'd have my answer.

Thanks, SC


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## Sgian Dubh (30 Jun 2022)

You're dealing with an intractable facet of wood's behaviour in that it is always adjusting its size in response to changes in relative humidity (RH), i.e., it shrinks as it loses moisture in response to lower RH, and swells when RH rises. RH changes hourly, daily, weekly, etc, all the way up to there being generally repetitive annual patterns. Those box lock joints are always going to shrink and expand over the seasons and they will always eventually telegraph through that leatherette(?) covering - is it leatherette? I've seen many examples of exactly this phenomenon, e.g., the through dovetails at the corner of cabinet carcases telegraphing through the overlaid veneer.

Your only option to essentially prevent this telegraphing is to redesign the construction to eliminate through joints, which basically means don't use your chosen box lock joints, and to incorporate some sort of joinery that ends at the outer corner of each the two parts as a mitre. There are various ways of doing this, all the way from the relatively complex hand made secret mitred dovetail joint to the simple mitring of each piece, plus additional internal and therefore hidden reinforcement, e.g., splines, dominoes, biscuits, and so on.

An additional element that will help is to make sure you use wood that is at an appropriate MC to start with, probably about 10 - 12% MC at the time you build, assuming these items are for indoor use, and not wood that is at a higher MC, e.g., 18 - 20% MC. Slainte.


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## peter-harrison (30 Jun 2022)

I agree with TheUnicorn- it's most likely that your timber isn't dry enough when you get it. If you can afford to, it would be a good idea to get a moisture meter and check a new bit of timber against one that's been in your workshop for a while.


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## Jacob (30 Jun 2022)

Wrong joint for the job?
I would have tongue and grooved it, with glue blocks on the inside. Would leave just one line visible and OK even if showing through.
Also a lot easier - those DTs are over the top really.
P.S. Wrong material for the job too. Ply or MDF?


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## deema (30 Jun 2022)

Slainte is spot on, wood expands and contracts at different rates longitudinal and laterally. The joint you have chosen is wrong for the application. You need a joint with no end grain showing.
For exemplary joinery you should look at hidden mitred dovetails. However, although not difficult to execute it’s all hand work and time consuming.
You need a mitred joint, so something that’s locked for instance with biscuits is quick and easy, however for shall or production runs a locked mitre joint is very effective. You can get a cutter for both spindle moulders as well as routers. That would be my choice.


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## Jacob (30 Jun 2022)

You don't need a fancy joint at all, as it's covered and out of sight.
Here's a pic of a T&G box joint. I've made hundreds of boxes like this, over the top of a TS.






A rebate would be even simpler to machine but harder to join as it would need careful clamping or pinning.
Either way rubbed glued blocks would add strength and very easy to do.
You flood each side with PVA glue, press and rub it into position and let go after a few seconds. That's enough to hold them in place as the glue goes off. They are sometimes shown drilled and screwed but this isn't necessary.
They are widely used in boxes like yours, or under stair treads and all sorts of cabinets.


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## Doug71 (30 Jun 2022)

If they have to be made from softwood and you want to finger joint the corners you could try Accoya which is treated Radiata Pine, it won't shrink but is expensive and a bit brittle in use.

Think I'd be mitring them.


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## Sea Chief (30 Jun 2022)

Scruples said:


> A hard wood would move less?


I'm adamant it would, but I cannot sell my boxes if hardwood, as the expense to make them is prohibitive, the customer doesn't want hardwood, & I cannot source hardwood out here anyway.. without travelling huge distances that is. It'd add msybe £25 to each box. I make no profit as it is on the pine one.


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## Sea Chief (30 Jun 2022)

peter-harrison said:


> I agree with TheUnicorn- it's most likely that your timber isn't dry enough when you get it. If you can afford to, it would be a good idea to get a moisture meter and check a new bit of timber against one that's been in your workshop for a while.


Understood thanks. Thing is out here, it's not only wild, but very moisture heavy too.

I can't keep a stock of timber in, as it cups if cut into manageable sizes.

I can only persue my idea, even if it has no followers, thst the laminated pine 'struts' of glue might be acting as a countermeasure to the shrinking. I can only hope really, along this avenue.


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## Jacob (30 Jun 2022)

Sea Chief said:


> I'm adamant it would, but I cannot sell my boxes if hardwood, as the expense to make them is prohibitive, the customer doesn't want hardwood, & I cannot source hardwood out here anyway.. without travelling huge distances that is. It'd add msybe £25 to each box. I make no profit as it is on the pine one.


If they are covered in vinyl you can make them of any old rubbish as long as it does the job. I strongly recommend the simple T&G joint plus rubbed glue blocks I've described above.


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## Sea Chief (30 Jun 2022)

Jacob said:


> Wrong joint for the job?
> I would have tongue and grooved it, with glue blocks on the inside. Would leave just one line visible and OK even if showing through.
> Also a lot easier - those DTs are over the top really.
> P.S. Wrong material for the job too. Ply or MDF?


Unfortunately an amp cabinet, needs to be both super-strong in the join type, & have no internal extra wood, as amp hardware goes up to the very inside edges. And 'fingerjointed' is just expected as it follows amp cabinet custom going back to late 1940's too. Pine is also inherrant to the sonic signature. And light enough. And affordable - just, still-. No other alternative alas.


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## Sea Chief (30 Jun 2022)

Jacob said:


> If they are covered in vinyl you can make them of any old rubbish as long as it does the job. I strongly recommend the simple T&G joint plus rubbed glue blocks I've described above.



The inside is seen Jacob, mostly empty really, but thanks for your thoughts.


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## Jacob (30 Jun 2022)

Sea Chief said:


> Unfortunately an amp cabinet, needs to be both super-strong in the join type, & have no internal extra wood, as amp hardware goes up to the very inside edges. And 'fingerjointed' is just expected as it follows amp cabinet custom going back to late 1940's too. Pine is also inherrant to the sonic signature. And light enough. And affordable - just, still-. No other alternative alas.


The wood is going to make no difference to an amp. Maybe it would for a speaker.
More research!


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## Sea Chief (30 Jun 2022)

Doug71 said:


> If they have to be made from softwood and you want to finger joint the corners you could try Accoya which is treated Radiata Pine, it won't shrink but is expensive and a bit brittle in use.
> 
> Think I'd be mitring them.



Hi Doug71. I just don't have this exotic option, here though. I'd have to travel 100m to cardiff or something.

No the problem is only with the pine I can get here, & fingerjointing it.

Thanks, SC


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## Sea Chief (30 Jun 2022)

Jacob said:


> The wood is going to make no difference to an amp. Maybe it would for a speaker.
> More research!



The amp has a speaker in it.princeton for eg.


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## Sea Chief (30 Jun 2022)

Jacob said:


> You don't need a fancy joint at all, as it's covered and out of sight.
> Here's a pic of a T&G box joint. I've made hundreds of boxes like this, over the top of a TS.
> 
> View attachment 138687
> ...



Hi again Jacob,

the rebating idea is interesting, but I just couldn't add the internal brace. This needs to be clear, hence f-joints chosen really.

Thanks, SC


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## Sea Chief (30 Jun 2022)

Im wondering now if I'm clamping too hard. As it seems this trait happens on the top & btm more than the sides, & I only use a diy set of clamps ( two bits of timber with 2 threaded rods linking them.. one each L and R side, I screw 2 nuts on the tops of them to put even pressure across & to clamp the timbers together vertically).

I then rubber mallet tap hard all over to close the joints, but no clamps per se sideways.. if you get my gist.

Maybe Im both putting too much pressure vertically, & maybe forcing too much glue out too. And possibly flooding the joints with too much glue too- I tend to remove a good lot inside corner & outside edges too.

Hmm.. sorry to plough my own furrow/ thoughts here chaps, but first time I've questioned my gluing & clamping technique.

Thanks for reading, SC


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## Inspector (30 Jun 2022)

Sea Chief. The glued up pine (I assume like ours for shelves made from shorts finger jointed end to end and then glued together to make a width, then shrink wrapped in plastic) is a little more stable because it was kiln dried before sizing and gluing together. Especially if the pine you are buying is construction wood, not pine meant for furniture. _The glue in the joints of the "laminated" boards adds nothing to the strength or stability of the board. 

_For wood to be affected by the clamping you would have to crush the fibres and that takes considerable force. You need to be a dimwitted graunch artist not to notice when doing it. We don't believe you are.

As I gave you my opinion of the joint to use I won't repeat myself and will bow out of the discussion as I have nothing more to add. Hope you get it figured out.

Be nice if you would post a few pictures of the completed boxes. We're interested in looking at them.

Pete


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## Sea Chief (30 Jun 2022)

Inspector said:


> Sea Chief. The glued up pine (I assume like ours for shelves made from shorts finger jointed end to end and then glued together to make a width, then shrink wrapped in plastic) is a little more stable because it was kiln dried before sizing and gluing together. Especially if the pine you are buying is construction wood, not pine meant for furniture. _The glue in the joints of the "laminated" boards adds nothing to the strength or stability of the board. _
> 
> For wood to be affected by the clamping you would have to crush the fibres and that takes considerable force. You need to be a dimwitted graunch artist not to notice when doing it. We don't believe you are.
> 
> ...


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## morqthana (30 Jun 2022)

Isn't the range of ambient conditions going to be even wider than one would normally expect for furniture?

Valve amps are going to produce a lot of internal heating and thus drying. If anybody ever takes one "on the road" then sooner or later it could be in the unheated rear of an uninsulated van in cold weather, and then humped into a venue with stage lighting and hundreds of sweaty, breathing, bodies.

OOI - if you go and buy an amp from Fender/Marshall/Mesa-Boogie/Orange/etc, how is the cab made?


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## Sea Chief (30 Jun 2022)

Im only keeping the pix up for a bit, like one of those yoofs 'app' newfangled things where you do a snap of yr junk, send it to your new gf & it vanish after a bit. or something.


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## Freddyjersey2016 (31 Jul 2022)

Rather late in the day - if I understood this box is being used as an Amp cabinet - is this purely for storage, or it is powered on while in the box - if it is powered on I would assume the box would get hotter than typical ambient - so then there are the possibilities - the box is changing size due to thermal expansion / contraction cycling; and the thickness of timber is changing due to lower moisture content due to higher temperature? Over time this would be apparent on the vinyl covering.


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