Thread: How do they make the substrate?

I reckon you're on the right path with your first option.

You can buy a... ummm... "flexi-MDF" which is basically just thinnish sheets which have saw kerfs cut partially through the back every few mm. It's flexible enough to bend through fairly tight radii. (I know what I mean, even if I haven't explained myself clearly. )

I think I'd make a torsion box type of affair, basically a drum from two MDF disks with this flexible stuff around the outside. The advantage would be that it'd only give you one joint in the substrate, where the two ends meet.

To get the curved sides you could stack "rings" of substrate with a solid top and bottom, they dont have to be full rings they can be cut in segments to minimise wastage.(think segmented bowl)

I'd say the base is blockboard ( like http://www.design-technology.org/Blockboard.htm ). Its a bit pricey, but very much favoured for this type of work. It also has very little expansion/contraction - in fact so little it is usually not considered in the design. Its surprisingly light, too.

If the veneer is professionally applied, then torsion boxes are out of the question. I rang every veneer outfit in Sydney and none would agree to apply veneer to a torsion box. They all use presses (with or without heat) and the fight with the customer when the torsion box bends and sags makes it not worth it.

Id probably cut the blockboard to size (acutally a little undersize), fix solid wood to the edges (like you have suggested, lots of segments), trim to oval shape, send off to professional veneer specialist for fixing of veneer to top and bottom, trim off veneer. Easy.

Arron

Thanks guys.

Three replies, three opinions. I love this forum ! !

Aron, I hadn't thought about the pressure. I've been playing around with applying veneer with an iron rather than a press, and am pretty pleased with the results. Should be less pressure than clamps. That said, if I go with a hollow design I'll need to make sure there's enough stiffeners inside to take the pressure of the iron.

It would probably also depend on what kind of base I use. Probably not a good idea to be attaching legs to a hollow spot...

Great food for thought.

Tex

As I've said on this forum before, if you are veneering something you are serious about, take it to the professionals and get it done. Someone like Specialty Wood veneer Panels at Smithfied (I have no connection - just use them a bit) will apply the veneer economically and worry free. Applying veneers with hot irons etc might look good for a few years but its not the way to build an heirloom.

Arron

Originally Posted by Arron

If the veneer is professionally applied, then torsion boxes are out of the question. I rang every veneer outfit in Sydney and none would agree to apply veneer to a torsion box. They all use presses (with or without heat) and the fight with the customer when the torsion box bends and sags makes it not worth it.

I’ll never fly on a jumbo jet again. Torsion boxes if made correctly are the lowest weight and strongest substrate for veneering by a mile.

Originally Posted by Tex B

Does anyone know? Any examples or WIP photos?
Tex

http://www.woodworkforums.ubeaut.com...ad.php?t=25852

Originally Posted by Lignum

I’ll never fly on a jumbo jet again. Torsion boxes if made correctly are the lowest weight and strongest substrate for veneering by a mile.
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Lignum, I suspect you misunderstood what I was saying. Torsion boxes may very well be light and strong but my point was that if you want to get a professional veneering outfit to attach the veneer then they wont do it to a torsion box. I know that because I rang every one listed in the Sydney yellow pages and they all refused point blank. Whether their objection is real or merely based on excessive caution is irrelevant in this context - they would not even discuss the matter or allow me to explain how I proposed to make the torsion box.

Tex, by all means make your own torsion box and apply the veneer yourself - but a piece of the size illustrated is really a bit big for a home job. Yes, you could make a caul press big enough to do it, or maybe buy a big vacuum bag outfit, but with a job like this costing approximately $40 when done by a pro then it seems a strange way to apply your time and money. I guess it depends upon how much of those two resources you have.

You can also iron on. The problem I have here is that most people who champion this method seem to have just finished the job, or maybe within the last few years. Not much of a test really, as I wonder how well it will be holding together in 30 or 40 years. Will we find the edges and corners starting to lift ?? (I'm excluding hide glue jobs here - I realise hot hide glue and hammer was the traditional method, and assume you are talking about modern contact cements and a clothes iron). No doubt if someone has some jobs done that long ago we will hear from them - and if the results are good then I'll change my mind as I would very much like to use that method myself.

cheers and merry christmas
Arron

Thanks Lignum. Now that you've refreshed my memory, I remember reading your torsion box post before. Expect I'll need to read it a few times before it fits in my head.

Aron, thanks for the input. I'd like to try and do it myself, as I'm thinking of a design on the top rather than a plain veneer, and would like to play around with it. The process is what I enjoy most, even if the results are not quite professional. I figure if I make enough garbage, eventually I will make something that's worth being proud of.

Would be interesting to see if anyone has had problems with ironed veneer over time. I don't really understand why glue pressed with an iron would be fundamentally different to glue pressed with a hammer or a vacuum, but like many things, I could be wrong about that.

Regards,

Tex

For what it is worth, I would never bother with iron on veneer (unless it is for edging on a cheap job). I can speak very highly of vacuum bagging veneer, which has resulted in a 100% success rate over a couple of hundred veneering jobs. Obviously, not all the exercises came out as I had planned but the botched efforts were the result of errors in planning or design on my part, not the application process. Good luck.

Tex stay away from iron-on veneer, its rubbish. If you dont have access to a vac bag or arnt interested in cauls (i hate them) use paper backed veneer and contact adhesive. If applied with care, you will end up with a top result and it will last years.

Dont forget to do a WIP

Iron on veneer is rubbish, as lignum says.
Listen to Aaron's experience. You can't go wrong.

Originally Posted by Lignum

Tex stay away from iron-on veneer, its rubbish.

Thanks, Lignum. Actually, I don't even know where to buy iron on veneer.

Have been playing around with applying 'normal' veneer (just thin slices of timber) using the hot iron method. AlexS and jerryc suggested it in an earlier thread, and here is the FWW article on it (may require subscription).

So far, it has been fairly easy to apply and the results look good. But, as Arron suggests, don't know how it behaves over time. Still, in theory if the glue is set and the veneer is flat on the substrate, don't see why it wouldn't last as long as veneer applied with a caul or vacuum bag.

But willing to learn if anyone has different experience.

Tex

Originally Posted by Tex B

Still, in theory if the glue is set and the veneer is flat on the substrate, don't see why it wouldn't last as long as veneer applied with a caul or vacuum bag.
Tex

I think the reason could be pressure. Would you glue timber without using clamps ?

I'm just speculating here as I have no real experience with iron on veneer. I have noticed with getting stuff done by Specialty Wood Panels that the presses they have must use tremendous pressure - when I have left faults in the substrate they have been pressed out of existence. Also, the veneer has that squashed flat look that I have achieved at home by tigthening up caul presses to the very max. This is despite the fact that the presses apply heat as well and the glue they use is heat setting.

Arron