What glue to use ?

[Big Fat Pig]

Dear All,

I am now embarked upon my most ambitious project to date in terms of getting it right. I`m building 2 oak bookcase/cupboard units for the lounge to sit in the alcoves adjacent to the fireplace.So, as it is going to be very much on show, it`s got to look as proffesional as it can.
I am, after taking some much appreciated advice from this forum, building carcasses from MDF which will be faced with oak veneered ply. I have glued up 1 side today using contact adhesive, but judging by the amount it took i will have to buy shares in Evostick to finish the thing. So my question is this :-
What is the best adhesive to use? or what alternatives could i use and still get a good useable result ?

I do have another couple of questions actually which i hope the panel will allow.They are concerning cupping.
The shelves are being made from inch thick oak boards, 210mm wide, and i am wondering if this dimension board would be prone to cupping or not. My initial thoughts are that over time the answer will be yes and so i am planning to rip them in half and edge jointing them with biscuits.Any comments ?
Secondly, which way do boards cup ? If you look end on at the growth rings so they curve up at the edges like a smile will the board cup up at the edges to make a bigger smile or will it cup down at the edges to frown ?

I may well come back and ask some more questions about this project so will take the opportunity to thank you in advance.
And when it`s all finished i might even take some pics and try to post them on here.


Piggy

 

[jasonB]

First question has to be why glue veneered ply to MDF rather than using veneered MDF?

The problem with contact adhesive is that you can get a bit of creap and it is also hard to get all the air out on large panels. A PVA would work better or titebond II, either way watch out for warping if only gluing ply to one side.

Depending on how well dried the boards are they may or may not cup, if you rip them in two then flip one half over before re-gluing.

The board will cup towards the center, in other words the smile will get bigger

JAson

 

[Paul Chapman]

Like Jason, I'm puzzled as to why you are using veneered ply on top of MDF rather than oak veneered MDF :? Seems a lot of work for no benefit.

I'm not a fan of contact adhesives for woodworking. I've had problems in the past (admitedly with Formica glued to chipboard, but the principal is the same) with the adhesive drying out completely after a few years and the glued on panel separating from the substrate. I would use PVA adhesive. But when you cramp it up use plenty of cauls and G cramps to even out the pressure.

Cheers :wink:

Paul

 

[Big Fat Pig]

Thanks for your replies chaps.

I wanted to use veneered MDF/Ply but it was a question of finding anyone who would supply the small quantity i needed, at short notice and without a hefty delivery charge. As it is,SWMBO`s father has a trade account with an obliging builders merchant and ive got all the MDF, Ply and Oak boards at trade prices. Believe me, i would much rather have gone the ready veneered route as gluing the stuff up is going to be a right pain in the bum. Mind you, i`ll be able to make full use of all my clamps.


Piggy

 

[Digit]

Personally I would advise ply shelves and lip the front edges.
Having said that I have used Oak for some shelves recently in those widths without problems, it all depends which way the grain runs.

Roy.

 

[HandyTim]

Surely any cupping would result in a frown?

 

[Mr T]

Hi

I thought the smelly evostick stuff was an impact adhesive, thats what it says on the tube in front of me! Is there a difference between impact and contact adhesive?

Anyway I would use a pva of some sort.

When timber dries it cups in the opposite direction to the annual rings and vice verse.

Chris

 

[Joe]

The longer growth rings tend to shrink more than the shorter ones, so the "outside" of the board (the surface that was nearest the outside of the tree) is likely to become convex if cupping occurs.

Joel

edit - sorry, the above sentence should read CONCAVE!!!

 

[TheTiddles]

Like others say it's an odd choice to veneer ply to MDF, that aside, I would apply PVA glue with a roller which is excellent for a flat even application of glue, then vacuum bag the two together. Contact adhesive a bit unnecessary and really expensive

Aidan

 

[Big Fat Pig]

Thanks for the replies. As i have mentioned, the decision to glue veneered ply on to MDF rather than buy ready veneered stuff was made out of necessity rather than pure choice, and given different circumstances i would have bought ready veneered panels. However, i couldn`t, i didn`t and i`m stuck with what i have for better or worse.
As for the cupping, i will be ripping the solid oak boards down to approx 100 mm wide and then joining them with biscuits, alternating the direction of the growth rings of course.
I have glued the 2nd panel up using PVA and it has gone OK, so thanks to you all for that advice.

Piggy

 

[Chris Knight]

I wouldn't rip wide boards myself unless it were really necessary - seems a waste of something that gets ever harder to get hold of. If they cup, you can always rip them later if using removable shelves. If they are fixed to the uprights in housings then this would help resist cupping in any case.