Would you trust a Domino...

[ricgstevens]

Folks,

Would you trust a Domino to make joints on a timber door?

What I have in mind is a solid Vic timber and glass pane door for my kitchen back door. The door is standard sized - about 2050 x 870 and will be built using ex 150 x 50mm timber for the door stiles and rails. The glass will be single pane, possibly 6mm laminated. It won't be a light weight door which makes me wonder if joints with multiple Dominos will be up to the tortional stress that doors exert on joints.

For the joints, I figured I would use multiple 50mm x 10mm dominos (the largest size) - even as many as 6 per joint, stack 3 side by side and double rows.

I've used my Domino for sheet work and other light duty applications and I am keen to really put it to the test. Besides, building a door using dominos will be the quickest one I've ever built!!

Thought, comments...?

Thanks

Richard

[bsrlee]

I don't know - only a thousand years of ship builders in the Mediteranean area used loose tennons to make ships of all sizes - up to the limits of shell first construction, around 1,000 tonnes displacement. Just like a DOmino, but they put pins in both sides - still holding together the hulls of boats they are finding on the bottom today.

So: if you are worried about it pullng apart, just put a dowel pin into the end of each Domino, you should have a thousand years or so before some archeologist pulls it apart.

[Lignum]

Still dont understand why Domi owners are so preoccupied with the standard 22 x 10 x 50 shop bought Dominos. We all know it will cut a max 32 x 10 x 56 so it makes perfect sence when constructing large items like the doors to use that setting and make your own larger tennon to fit.


On that 150 x 50 rail i would set the scale "not the sliding stop" to 15mm and use the index pins for 2 consecutive cuts, then drop the scale to 35mm (need to remove the plastic dovetail strips) and repeat the cuts.

That would be perfect spacing in depth for the stile/rail and leave plenty of room in the width for glass panel rebates and as strong as any standard mortice and tennon

[ricgstevens]

Lignum,

I did consider taking advantage of the maximum capacity of the domino and producing custom sized loose tenons however I want to avoid having to produce them. Furthermore, factory dominos have multiple splines which offer better adhesion.

I want to come back to my original question "would you trust large sized dominos to make a door"

Richard

[Lignum]

I did consider taking advantage of the maximum capacity of the domino and producing custom sized loose tenons however I want to avoid having to produce them.

Producing your own is so much quicker and cheaper than buying them. I havnt bought a box since Xmass and doubt i will ever buy them again. How many off cut strips do you rip that normaly go in the bin or the pot belly. 20 minutes with off cut strips through the thicknesser and gang dock them on the TS sled will = a few hundres bucks of shop bought Domies.

Furthermore, factory dominos have multiple splines which offer better adhesion.

This could be a whole new thread in its self but the Festool/Domi members have stopped posting for some unknown reason? Having said that only on the sides of the domies (just like dowels) are ribbed and the front surface is just Festool stamped. Think about a traditional tennon? They are considered perfect and now one scores them for better adhesion.

And as i said i make mine and the larger surface area is heaps better than the factory Domis and they fit like a thumb in a bum. And the $$$$ you save is the bonus

[eddie the eagle]

Hi Richard,

I'd make the tenons a bit deeper (through or about 2/3 of thickness) as the door has a lot of racking forces. They might hold, but I wouldn't do it personally.

However, if it's a door in your house and you don't mind repairing it later, as well as wanting to give it a go, I'd say do it.

My gut feeling is about a 30% chance of it still holding in five years. Maybe a bit higher if you use epoxy as the glue.

If you do use epoxy, you need 1/2mm minimum or more (a mm) gap between mating surfaces to allow the glue to develop maximum strength.

Cheers,

eddie

[Rocker]

Eddie,

Is your statement that you need a 1/2-1 mm gap to allow epoxy to develop maximum strength based on any scientific testing? I would be interested to know where you learnt that.

Rocker

[eddie the eagle]

HI Rocker,

It's my first degree (materials engineering)

I'll google around for five minutes and see what I can dig up.

In case I can't find anything, the shear strength of epoxy is developed from thickness of the glue (it's a thermosetting polymer, like bakelite), and is maximum at about (?) 1/2 -1mm, but definitely not at zero thickness, as epoxy is not a penetrating glue [see final edit].

Cheers,

eddie
To get it to stick at maximum adhesion, you need a well keyed surface as well

edit; the google links

(before I do them, I've epoxied broken plane totes and squeezed most of the epoxy out to try and improve appearance, just broke again on the glue line. With a thicker glue line, they've held well.)


http://www.defelsko.com/technotes/ad...s/adhesive.htm (2mil = 0.05mm, 4mil = 0.1mm)
http://multimedia.mmm.com/mws/mediaw...666yz&COrrrrQ-
http://www.scielo.br/scielo.php?scri...92003000200014
http://www.nuplexcomposites.co.nz/ht...volume%202.pdf
http://www.sciencedirect.com/science...3007e26d209f65
http://www.westsystem.com/webpages/userinfo/manual/ (see fig 11 and text -> inferred)
http://www.auf.asn.au/scratchbuilder/joints.html#joints (refers to maximum thickness of 1mm, preferably less)

Data appears to refer to an optimum glue line thickness of 0.1 - 0.15mm, with exception of west epoxy who are in keeping with training. I'd stick with mfg recommendation against training. The 1/2mm was the number I recalled specifically as we all used it often and still do so occasionally.

In any case, epoxy requires a minimum glue line thickness to develop bond strength as epoxy derives its strength from development of a cross-linked network. Joints need to be loose to allow this to develop as it's a different bonding mechanism to PVA.

[final edit] there has to be some penetration of epoxy resin into the wood to improve strength, or else it would fall apart on tension. What I referred to here was that the viscous epoxy has significantly less penetration into each workpiece than the PVA glue.

[Rocker]

Eddie,

Many thanks for your comprehensive reply. I will now abstain from hijacking this thread any further.

Rocker

[eddie the eagle]

No dramas, Rocker.

Just worthwhile pointing out as a summary reply that the manufacturers' recommended glue line thickness for epoxy is in the vicinity of approx 0.1-0.2mm, ie: a visible glue line.

Now, back to door making . . .

Cheers,

eddie

[scooter]

Thanks also for the detailed & informative post, eddie.

Learn something new every day.


Cheers................Sean

[zuma]

My gut feeling tells me the weight of the door and glas panel and the stress of opening and closing the maximum domino size won't do it in a simple door with 5 styles (2 windows or 1 window and a panel or two panels). I think the maximum domino size is wide enough but certainly not long enough to give that extra supporting capability that's needed in doors.

However if you do a door with 1 upper style and lets say five lower styles stacked above eachother you'll get a door with enough supporting capability. The stacked styles replace the need of a panel.

[dirtydeeds]

i made a framed ledged and braced gate using 10mm dominos

its been in position for 8 months or so with rain and snow and gales

no problems

[Lignum]

I think some are getting all to technical. If a 28 x 10mm tennon is a "pefect" fit in a mortice, glued with quality glue, then at the end ot the day how much weaker would that be compared to a 70mm tennon?

If their were 4 @ 28 (56) x 10mm Domis joining a stile/rail it would more than sufficient.

But it comes back to how you use your Domino. It appears (from the majority of Domi threads) that everyone is so stuck on the mortice sizes of the standard Domino
The Domi is the perfect reference for perfect mortices. So if you do have concerns then why not do this as i previously posted

Just use the Dominos accuracy to start with and just pair down the perfect parallel sides another 50 or so mil by hand.

[eddie the eagle]

You must be referring to me, Lig. We all have our own opinions, but it's how you put them across that matters.

Apologies, as I was asked why epoxy needs glue line thickness and to provide some references/additional info if possible.

What you say will work (use the Domino as a starter/mortising gauge and then chop the mortice by hand.)

I've had to make a fair few doors before.

As I said, I'd give the domino about a 30% chance of long-term success, slightly more if the glue was epoxy. THis, of course, is a gut feel and subjective.

The depth of the mortise is to give resistance to racking forces, and if it's too shallow, either the stile will split at the end of the mortise or the racking forces will win and rip the tenon out of the mortice. This is more likely to happen if an exterior grade PVA is used as PVA is subject to creep.

You'll need a loose fitting tenon (but not too loose) if you use epoxy.

CHeers,

eddie