table top glue

[dennford]

I have been conned into making a large dining table for a nieghbour who is fool enough to think that I can do the job.

The table is fairly straight forward 4ft x 8ft 42mm thick tas oak top. 90mm x90mm tas oak legs fastened inside a tas oak skirt, the top will be fastened with those steel top clips that go into a slot.

Now this is how much I know - what sort of glue to use for jointing the top, I can't decide between pva, timbecons pvr or titebond 2. I reckon that any of them would do but I thought I may sound you all first.

Denn

[Hobbyhorse]

Denn,
I would use an epoxy however not everyone would agree with that.

Rhys

[Justin]

I'm a big fan of Titebond 3, it doesn't seem to creep at all.


Justin.

[dennford]

Denn,
I would use an epoxy however not everyone would agree with that.

Rhys

When you say epoxy, do you mean a two pack - similar to araldite? that'sthe only epoxy that I know of.

Denn

[dennford]

I'm a big fan of Titebond 3, it doesn't seem to creep at all.


Justin.

Is there any other differences between titebond 2 and 3?

Denn

[orraloon]

Denn,
As you said any of them will do. I have used pva and titebond 2 in the risers of archery bows and they are under a lot more stress than a table top. The success of a joint is in how well it fits and that it is clean before glue up. I clean the surfaces with spirit or acetone just before I glue them.

Regards
John

[Justin]

Is there any other differences between titebond 2 and 3?

Denn

Hi Denn,

I don't know mate, I went from Triton woodworking glue to Titebond 3, so I've never used 2.


Cheers,


Justin.

[scooter]

I wouldn't use a standard PVA, not because of strength but because the joint can creep, ie the joined components can move fractionally out of alignment. This can happen some time after glue up, leaving you with misaligned joints that had been sanded flush. On a tabletop this shows up as a very slight "step" between boards.

I'd go with an aliphatic resin type PVA (aka crosslinked PVA or "yellow glue") , these are resistant to creep.

Could also consider using a polyurethane glue such as Vise or Selleys Durabond.

Yellow glue - easy cleanup, economical, good shelf life.


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

[dennford]

That has given me more info' than I had - but it also means more to think about. Anyhow I shall let you know which way I go and also any problems or advantages that I encounter whilst gluing up the top.

Thanks for your input
Denn

[Hobbyhorse]

Denn,
I have used a lot of epoxy in laminating work in boats and have just about finished a wooden clock movement in which I made my own plywood out of oak and glued the laminations with epoxy with which I have made the cogs. The glue I am using at the moment is a CRC product which is two pot with equal parts as a ratio. I bought it from the local builders supply here in NZ and it is referred to as builders epoxy. Epoxy does not creep, sands well and gives a good strong joint. It also is good at gap filling where necessary.

Rhys

[jefferson]

Denn,

I've glued up stacks of bench and table tops out of Vic Ash, mostly using PVA or the "improved" Triton stuff.

You will have no worries using either - they say you can "guarantee" a stronger joint line than the timber itself.

If you use biscuits or dominos, you won't have any problems with creep either, just make sure your boards are jointed true and are fresh so that the glue sinks in.

One thing I did note from your original message was about using metal clips to secure the top.

I wouldn't. Without checking the expansion tables, a top over 4ft wide probably will expand +- half an inch at least over a season. That puts a lot of stress on those fasteners, even with KD timber.

I suggest wooden buttons instead, suitably "greased" with wax. Some of the metal fasteners I've used have been tested to the max - or rather, the whiteboard they've been attached to has protested. Accept the timber movement and allow for it - at your peril if you don't!

Jeff

[dennford]

It seems that strength is not going to be much of a problem - most of these glues will give a joint stronger than the wood itself providing I have prepared the edges properly. The main thing seems to be ease of use.

Jeff your comments on expansion are of interest - do you know where I can find expansion table? or should I say one that I (average intelligence - I hope) could understand.

Denn

[jeffhigh]

I would go with titebond 1 (original)
PVA glue creep is not just a problem with joints becoming misaligned, over time the pva glue can expand and show the lines. I have a tabletop I did 28 years ago with this problem .
PVA is also move difficult when sanding, softening and smearing, amd loading up the paper.

[BlackAdder]

Denn,

I suggest wooden buttons instead, suitably "greased" with wax ..... Accept the timber movement and allow for it - at your peril if you don't!

Jeff

G'Day Jeff,

The movement is also of interest for me, but not the expansion tables, rather your suggested method of "buttons". Could you explain more please? How do you use these "buttons", what do they look like, how do you prepare both mating surfaces?


BlackAdder

[jefferson]

Gents,

I just ducked out to the shed and found some basic info for you.

The "Furniture Design Guide" - which looks at Vic Ash, messmate and redgum - states:

"... a 100mm wide backsawn board of River Redgum will expand by .31mm for each 1% increase in moisture content. If the moisture content were to rise from 10% to 12% then the board would expand by 0.62mm..."

Vic Ash, according to the guide, will shrink or expand at a slightly higher rate - 0.35% for backsawn boards, 0.22% for quartersawn.

So if your table is say 1200mm wide, it can expand significantly - .70mm for a 2% increase in MC ie. 8.4mm. Double that if there is a 4% change in MC.

All this assumes you don't seal the table top (sealing slows the gain or loss of moisture very well).

Wood buttons have been around a long time and there's probably a thread or two on the topic somewhere.

All you need to do is cut a groove on the inside face of the rails, say 3/4 inch from the top. The wooden L-shaped buttons slot into the grooves and are fixed to the underside of the table.

You leave a gap between the rail and the button to allow for expansion, with spacing around 6-8 inches apart, maybe more.

Hope this helps.

Jeff