Domino glue up problem

TheLastTool

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Joined
Nov 6, 2023
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6
Hi,

I'm a new Domino XL owner, in fact its my first Festool tool but certainly not my first tool! I'm having some issues with my first glue up and hope someone can offer some solutions.

I'm making a table top from 6 oak boards that are 1900mm long, 29mm thick and widths ranging from 125mm to 230mm. I've planed all the joints on a planer (and I checked that the fence is at 90 degrees) and when dry fitting them without dominos the joints are pretty much perfect. I'm using 12mm x 80mm dominos which I've cut from the Festool 750mm lengths and bevelled the edges as someone on this forum suggested. I cut 40mm mortices with the Domino about every 185mm to give me 9 dominos along the length of the board. The mortice at one end was cut tight with all the others cut on the loose setting. I brush glue on the face of each domino and a light coating in the mortices.

The two problems I'm experiencing are:

1. Even though I'm using 7 Bessey REVO KRE clamps it's a major struggle to bring the two boards together and it requires some major force with the clamps wound up as tight as I can get them.

2. The finished joint isn't as good as the dry fit, i.e. you can see the joint because the two faces don't mate perfectly.

Many thanks in advance.

Graham

 

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Firstly what exact size are you cutting the dominos to, as they are all a little undersize the stated dimension to allow for glue.

The 80mm dominos from memory are actually around 75-76mm long. So it could simply be that there isn't enough space for the glue squeeze out to bring the edges closed, as the glue is building up and creating pressure at the ends of the dominos.

Also, what glue are you using and how long is it taking to apply the glue to all surfaces and start the clamping? Some glues have a low work time, and actually start setting up when the surfaces mate. For this reason I apply a reasonably liberal amount of glue to all surfaces keeping them apart till all are coated, and then I quickly assemble and clamp to get a good squeeze out.
 
Thanks. I made the dominos exactly 80mm because the mortices are 41 - 42mm deep. I'm using Titebond 3. I glue the mortices into the first board then apply glue to the joint faces then quickly to the half of the dominos protruding from the first board and the mortice in the second half board.

I'll certainly try shortening the dominos to 76mm as you suggest.

Thanks,

Graham
 
Just shortening the tenons might do the trick but I’d also suggest using less glue in the mortises. Strictly speaking you don’t really need any to keep those boards together once the edge glue has dried. I usually just use the Dominos for registration so I can get the assembly clamped as quickly as possible.
 
Thanks. I didn't put much glue on the domino before bringing the joints together and I also did it pretty quickly (2 mins) but perhaps it was enough to swell the dominos slightly and cause the clamping difficulties. Am I using the correct length and number of dominos?
 
If you do what luvmytoolz said you should be fine.

I think the number of Dominos is good.

You could drop down to 10mm Dominos and they don’t need to be as long.

You workbench looks nice! And welcome to the FOG.
 
Michael Kellough said:
snip.

You could drop down to 10mm Dominos
Snip
Amen. Just follow the 1/3 stock thickness guideline. I'd use 10mm x 50mm dominoes.

The edge joint by itself is strong enough without dominoes, so I'd use fewer dominoes IF the boards were all flat. If not, the no. you used (for alignment on the registration faces) seems to be right.
 
What Chuck said, sometimes when I’m using dominos in this application, I don’t even glue the dominos in. They are there for alignment only.
 
I would second the possibility that the tenons are too long. The tenons primarily, for panels, are for alignment and not to hold the boards together.

I have done many large panels. I never try to glue up more than one joint at a time. I start with glueing up  boards by twos. Then add another section until they are all together.
 
Birdhunter said:
I would second the possibility that the tenons are too long. The tenons primarily, for panels, are for alignment and not to hold the boards together.

I have done many large panels. I never try to glue up more than one joint at a time. I start with glueing up  boards by twos. Then add another section until they are all together.

Thanks. I'll try shorter dominos. I'm also only glueing one joint at a time - there's no way I'm fast enough with glue and clamps to do anything else anyway!
 
Michael Kellough said:
If you do what luvmytoolz said you should be fine.

I think the number of Dominos is good.

You could drop down to 10mm Dominos and they don’t need to be as long.

You workbench looks nice! And welcome to the FOG.

Thanks. The workbench is the biggest thing I've ever built but well worth the time and effort. I can highly recommend the parts for the quick release leg vice. I got it shipped over from the US fromhttps://hovartercustomvise.com/
 
Late to the comments, but I would agree with the above. Shorten the tenons a couple of mm and don't bother with gluing them. The strength of the glue bond on edge grain is superior to the wood itself.
Where glue on the tenon matters is places like face frames and frame/panel doors. It's a smaller contact area in the first place, plus half of it is end grain.
 
what crazy race guy said, except shortening the tenons. Me thinks your putting to much glue in the mortise and when you tighten the clamps your not allowing the glues to squeeze out of the mortises.
 
In looking at the picture I see a rabbit on the bottom edge of one of the pieces. I am wondering if this is causing the joint to bow upward and open.  Are the dominoes install during the dry fit up? If so and the dry fit up is ok then the problem is in the clamping or as others have said to much glue.
 
I suspect
Most of us who glue the dominoes do the same as you described: glueing them in one board first, then applying glue to the other board’s mortises and the joining surfaces, and then sweating them together. One issue I have experienced is, even after doing a dry fit that is perfect I inadvertently fail to seat one domino to proper depth in the first board, it gets set up and won’t budge when it bottoms out in the second board. If I’m lucky, I can get them apart, saw that one down to proper length, clean stuff up and recover. I’ve taken to doing a Quick Look to make sure they are set properly now.
 
chris s said:
In looking at the picture I see a rabbit on the bottom edge of one of the pieces. I am wondering if this is causing the joint to bow upward and open.  Are the dominoes install during the dry fit up? If so and the dry fit up is ok then the problem is in the clamping or as others have said to much glue.

Agreed, at least partly. The contact with the long edge of the rabbet would create a bow downward, but that should be negated by the clamp bars. Ultimately though, there was no mention of a bow, just not closing.
Tite-bond 3 is a fairly slow setting glue, as far as typical wood glues go, but it will still cause swelling/tightening of the tenons.
Nine Dominos may be too many, especially if your boards were nice and straight, in the first place. This increases the difficulty of pressing this all together.
As an aside,
unless there is some specific reason that you can't do it later, I wouldn't cut the rabbet first. You risk denting the edge because of the lack of surface area on that edge.
Also, your clamping pressure would be far more even if you clamp from both sides. All of yours are on the bottom, a few from the top, could straighten things enough to close up better.

This was all 2 months ago. Did you finish this project? Better results?
 
A few other late suggestions:

When you wrote "I've planed all the joints on a planer (and I checked that the fence is at 90 degrees)", I assume you mean joiner.  I suggest you using the "inside/outside" jointing approach when you join the edges, that assures perfect alignment even if your fence or technique is a little out.

I also suggest alternating the clamps (under and over) when you do the glue ups.    That also helps keeping the correct alignment.

I am also curious how it worked out.

Bob
 
greg mann said:
Snip. One issue I have experienced is, even after doing a dry fit that is perfect I inadvertently fail to seat one domino to proper depth in the first board, it gets set up and won’t budge when it bottoms out in the second board.Snip.

After applying glue to the mortises and dominoes, I always hammer all the dominoes home on the first piece with either one of these (on the hard face, white or black) before working on the mating board:
[attachimg=1]

or

[attachimg=2]

I tend to use the Lixie on the largest dominoes (8mm & 10mm).

 

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ChuckS said:
greg mann said:
Snip. One issue I have experienced is, even after doing a dry fit that is perfect I inadvertently fail to seat one domino to proper depth in the first board, it gets set up and won’t budge when it bottoms out in the second board.Snip.

After applying glue to the mortises and dominoes, I always hammer all the dominoes home on the first piece with either one of these (on the hard face, white or black) before working on the mating board:

I do the same, but you still have to be careful about hydraulic lock. Over forcing with a mallet can push excess glue outward. Where "outward" may be is anybody's guess. The design intent of the Dominos is for it to come back out through the hole, but that doesn't always happen. That pressure can split solid wood, MDF and plywood. Particleboard usually fairs better, since the lower density will allow the glue to fill in the spaces.
 
Crazyraceguy said:
Snip.Over forcing with a mallet can push excess glue outward.
Snip.ll allow the glue to fill in the spaces.

I know excess glue happens to some people, but it is not how I do things in my shop. I prevent excess glue squeeze-outs by applying the right amount of glue. Experience definitely helps here.
 
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