Edge glued boards for outdoor storage box lid gone wrong.

[MaxHill]

Hi,

So I've attempted my first edge glue-up. Boards are oak 90mm wide x 1800mm long. I used domino for alignment, titebond III as glue and 3 clamps.

Anyway , I tried gluing 3 boards and I got tiny gaps between my seams when I hold the panel against the light and inspect very closely. I only have 3 sash clamps which is probably way too little for 1800mm board. I need more clamps before attempting the next. How many do I need for 1800mm long boards? 1 per 300mm?

Also, can I fix the current gaps? Its supposed to be a weather proof lid, so they aren't useful with hairline gaps. Can I get glue in there somehow and reclamp or is this a lost cause and I should rip the boards apart again and re-glue?


Thanks

 

[Beau]

If you can make them slightly concave along the length one clamp can be enough. I must admit to rarely doing this but it can be done. I would probably be looking at five for 1.8m. Doubt you can re-glue but I would use epoxy resin to fill if you felt the joint was otherwise sound. Did you clamp them in the hot weather? Maybe the glue was going off before you got them fully together. Not used Dominoes but read on here a few times that they can be tight. Might be that they have made it hard to clamp up.

 

[pulleyt]

I'm no expert but my guess is that you need to clamp, temporarily at least, where you have used a domino to make sure that the domino is properly seated. Once seated you can move the clamp to the next domino if you don't have enough clamps for each domino.

Trevor

 

[MaxHill]

Doubt you can re-glue but I would use epoxy resin to fill if you felt the joint was otherwise sound. Did you clamp them in the hot weather? Maybe the glue was going off before you got them fully together. Not used Dominoes but read on here a few times that they can be tight. Might be that they have made it hard to clamp up.

So realistically, how do you get filler in such small gaps? We're talking hairline. Usually its so thick. Do you thin it?

I used the longer 50mm x 8mm dominos and they were a bit tight. Had to use mallet to get them in. I also was too stingy with the glue on the edge I think. Not a lot and consistent squeeze out.

I've ordered 5 clamps to add to my 3. But in the meantime I've just done a new test with shorter off cuts of the oak. I used shorter 8mm dominos and they were looser. Used more glue as well.

 

[doctor Bob]

1800mm, I'd do 5 below and 5 over the top to keep it flat, thick packers as well to spread the pressure.

 

[mbartlett99]

Like what Bob said - 3 isn't slightly close to enough.

 

[AJB Temple]

If you really want this to be watertight, forget filler. In fact forget edge jointing without t&g for outdoor use ion a box lid. Rip them down the joints and do a half lap on each edge with a router or table saw. Get more clamps as Dr Bob says.

 

[Beau]

So realistically, how do you get filler in such small gaps? We're talking hairline. Usually its so thick. Do you thin it?

West system is very thin without thickener and will run into very thin cracks. Presuming Titebond is not gap filling so more glue would not have added much more strength just would have filled the cracks. West system is nothing like Araldite epoxy.

 

[MaxHill]

If you really want this to be watertight, forget filler. In fact forget edge jointing without t&g for outdoor use ion a box lid. Rip them down the joints and do a half lap on each edge with a router or table saw. Get more clamps as Dr Bob says.

Actually it makes total sense, thinking about it. Much more contact area for glue, less chance of an opening developing for water ingress, etc.

I'm gonna rip the boards and get a t&g or halflap bit for my router table.

Ordered 5 clamps as well.

 

[Beau]

Best option really but glue is not there to fill the gaps. The joints need to be good with no hairline cracks in the dry glue up.

 

[custard]

How many sash cramps do you need?

Imagine the pressure from the sash cramps fanning out at 45 degrees like this,

The entire glue joint needs to be covered within those imaginary fan shapes. A wider glue up needs fewer cramps, and a narrower glue up needs more cramps. So 3x90mm boards equals a 270mm wide glue-up. Along an 1800mm length you'd want at least six sash cramps.

With a sprung joint (ie, you've planed a minute hollow in the centre) you theoretically need fewer cramps. That's sometimes true for very light duty applications, but for anything subject to outside weather or heavy loadings it's too much of a risk to use fewer sash cramps.

People often say they use dominos just for alignment, I suspect the real reason is they're not confident in their edge jointing ability. That's a mistake, because ripping down through the faulty glue lines will expose the dominos, and make it almost impossible to now plane the edges true. Also, Dominos are made of Beech, so they'll rot if used outside, you need "Sipo" Dominos for outside use.

Repeating this job with half lapped edge joints will make the glue-up a bit trickier, half lap boards tend to roll up under cramp pressure. If you're really unsure about your edge jointing ability then you'd be better off making tongue and groove edge joints or use a loose spline, plus use a truly waterproof and gap filling glue like Cascamite.

But best of all is to invest the time and learn to edge joint properly. If you've bought a Domino machine I guess you're taking woodworking seriously, the truth is there are real limits as to how far you can progress as a woodworker without being able to edge joint accurately and consistently.

how-to-edge-joint-t112936.html

 

[Jacob]

'Oak', 'Edge glued' and 'outdoor' are contradictions in terms.
It won't work unless heavily painted, or jointed like a boat with copper nails, or covered in roofing felt, or shiplap, shingles ......... etc. etc.
Back to the drawing board?

 

[MaxHill]

'Oak', 'Edge glued' and 'outdoor' are contradictions in terms.
It won't work unless heavily painted, or jointed like a boat with copper nails, or covered in roofing felt, or shiplap, shingles ......... etc. etc.
Back to the drawing board?

Plan B is exterior grade plywood lid and paint it like the box itself.

I chose oak because it was listed as outdoor resistant , looks good and I thought surely people made weather resistant solid wood outdoor boxes before exterior grade sheet wood.

Are you saying I'd be wasting my time edge gluing even with T&G?

 

[Jacob]

..
Are you saying I'd be wasting my time edge gluing even with T&G?

Yes.
Especially T&G - the whole idea is to allow a bit of movement. If you glue it it could self destruct.
Plan B sounds good!

 

[MaxHill]

...

But best of all is to invest the time and learn to edge joint properly. If you've bought a Domino machine I guess you're taking woodworking seriously, the truth is there are real limits as to how far you can progress as a woodworker without being able to edge joint accurately and consistently.

...
how-to-edge-joint-t112936.html

Thanks for all that useful info. The reasoning for domino for me in this joint is that the stock is not 100% uniform because I buy it online. Some boards might have a slight cup or warp. I haven't got the tools to machine my stock. With the dominos every 30cm or so, it gives you a way of correcting this , if that makes sense.

It is giving me some pause. This was supposed to be an easy project to learn to use the tools and clear some space in my workshop. I'm happy with my first box:

I fear I bit off a bit more than I can chew with the lid I had planned. It's quite big with 180cm for a first edge jointing glue up. Don't think I have the experience / skills / tools to make it happen. Maybe I should save the oak for smaller scale project and go for exterior ply and paint.

 

[Jacob]

If it's staying outside I'd put it under a bit of a roof, like a bus shelter or a lych gate. Perhaps add walls. A tent?

 

[MaxHill]

..
Are you saying I'd be wasting my time edge gluing even with T&G?

Yes.
Especially T&G - the whole idea is to allow a bit of movement. If you glue it it could self destruct.
Plan B sounds good!

OK , looks like I'm saving the oak for something else

 

[MaxHill]

If it's staying outside I'd put it under a bit of a roof, like a bus shelter or a lych gate. Perhaps add walls. A tent?

Maybe I buy a bigger plastic box from homebase and put this one in it?

 

[Deadeye]

Well, for what it's worth, the box looks great!

 

[pulleyt]

I'm no expert but my guess is that you need to clamp, temporarily at least, where you have used a domino to make sure that the domino is properly seated. Once seated you can move the clamp to the next domino if you don't have enough clamps for each domino.

Sorry, I wrote the reply in a bit of hurry and reading back it doesn't make much sense.

I've learnt the hard way that any time I use a domino to joint boards in carcass work, rather than edge jointing but the principle is the same, I get best results when applying the clamping pressure directly in line with each domino to ensure that the joint is fully closed *at the domino*. Where I only clamped between two dominos, the domino sometimes holds the faces apart a fraction leaving a tiny gap in measurement but a virtual canyon to my eyes

I agree that perhaps this wasn't the time to use Domino's but I do love them in other circumstances and I wouldn't want you to think they are troublesome

It's a fine looking box and I'm sure you'll find a use for it even if it isn't for the original purpose.

Trevor