Thread: Red gum

Did you joint the edges or just pull boards up tight with clamps?

Macca,

Potentially its the glue. I know that AV203 is often used for redgum. Check out the following site:

http://www.avsyntec.com.au/Adh/case3.htm

Also, this is a quote from it:

"Edge to edge glued components (eg tabletop or benchtop) where the glueline creep is likely to result in ‘visual’ problems (uneven surface) the AV203 modified urea formaldehyde is recommended."

Hope this helps.

Regards,
Mike.

Thanks guys. I used a festool domino joiner with a 30mm domino approx every 30cm

I glue a lot of redgum and the AV203 is the way to go and you need a freshly machined surface as well. If the timber was laying around for a few days after being edge jointed, the glue does not bond as good

Hi Macka,

I've made several tables in redgum, Jarrah and Blackwood, all using the Domino, with no problems. What length and depth are the boards that you used? For anything over a metre and depth of 25mm+, I would use either 6x40 or 8x40 at the same intervals you are using. Its possible there is too much stress on the joints. A little deeper mortise may be all you need. If you really want to hit it with a sledge hammer, use a 10x50mm:eek:

Regards,

Rob

Sounds like I need to use bigger dominos as each table was over 2 meters.. Also does any know what website I can purchase AV203 from?

Try this mob for the AV203. It is listed on Sentry's site as a distributer

<TABLE cellSpacing=1 cellPadding=3 width="100&#37;" border=1><TBODY><TR><TD vAlign=top width=88>Mildura</TD><TD vAlign=top width=128>Key & J Koch</TD><TD vAlign=top width=105>59 The Crescent</TD><TD vAlign=top width=119>Ph:03 5021 3940
Fax:03 5021 3942</TD></TR></TBODY></TABLE>

I did see that list earlier today and called them and they have changed owners and no longer supply it.

macka
can you please respond to the question regarding whether the edge joints were fresh or a day or more old or not jointed at all

if either of the later two, larger domino biscuits or a change in glue is unlikley to prevent your problems recuring


ian
you

the edges were jointed and they were a day old.. Can you tell me why it would make a difference please?

Macka

Posters above have commented that with Red Gum the age of the jointed surface affects how well the glue bonds. Other timbers, one is teak, exhibit the same property. It's something to do with oils/resins in the timber. Also some timbers need to be wiped down with acetone immediately before glue-up.

Likewise some of the polyurathane (?) glues need the joint to be wiped with a wet cloth immediately before glue up.

as to the biscuits, essentially they are there to aid alignment, plus add bending strength to the joint. bending strength is very important with case work but not really an issue with a tabletop. The problem you described sounds as though the glue hasn't bonded to both sides of the joint. With modern glues and long grain to long grain joints, if the timber srinks away from the joint enough to open up the joint, the timber should fail not the glue.

ian

Another question: Are the tops screwed down to a frame/stand, or are they still free-standing & still coming apart.

If they are screwed down, the problem could well still be expansion/contraction - just unscrew the top and elongate the outer screw holes a bit more - say add about the total ammount of the splits in each hole. You may want to rout an elongated recesses for the screw heads & use pan head screws with washers so they can skid about without digging in also.

Interesting. I too am in the Mildura area and I too am working with river red gum. In fact, I start in the new year on our new kitchen benchtops based on some air dried 100x50 that'll be remachined and laminated. So this issue of seperation is of relevance to me.

I'm no glue guru (or joinery expert either) but it sounds like a mixture of factors but technique is playing a part. I've always used PVA or that yellow PVB (?) for long grain laminating and never had any dramas with the results. I avoid biscuits where possible prefering dowels if required - but if I can I'll use neither. Liberal glue, no air in the joint and lots of pressure. Thus far this technique has served me well.

Hopefully it'll do the trick for my benchtops. But I was going to seek advice as to the preferred glue for this sort of operation....perhaps now I don't have to.

The problem may also be that your KD timber hasn't properly stabilised to the environment it was standing in prior to working of it....

Macka,
You state that the timber is kiln dried to around 10-11&#37;, have you personally confirmed this or is this what you were told?