Tannoy Monitor Gold 12" build.

[Kno]

 One down, nearly.  How many more?

[awkwardbydesign]

Base and back veneered on first cabinet.  I've fitted the threaded inserts to the base, so I can add some feet when I stand it up, to avoid marking the surface.
The curved sides are going to be fun to veneer, using contact adhesive.  As soon as the veneer touches it will stick, so no margin for error. Times four!

[Tomcat1969]

Looking good Richard.

[regaplanet]

Base and back veneered on first cabinet.  I've fitted the threaded inserts to the base, so I can add some feet when I stand it up, to avoid marking the surface.
The curved sides are going to be fun to veneer, using contact adhesive.  As soon as the veneer touches it will stick, so no margin for error. Times four!

Well, this shoud be very, very interesting! I like them very much!

[Firebottle]

So am I!  As I'm making most of it up as I go. 

Isn't that the best way?
Looking fabulous!

[awkwardbydesign]

One curved side successfully veneered.  I coated both surfaces with contact adhesive, and when it had dried enough I laid 3 strips of wood on the cabinet, lined up the veneer and pressed the front edge down.  Then I removed the first strip of wood, pressed down a few more inches of veneer, removed the next strip, repeated and worked my way to the back edge.  Seems OK, so I'll give it a coat of base coat tomorrow, and iron down any bubbles that appear.
Just another 3 to go!

[Robert Young]

Gorgeous. Truly superb work Richard. I can't wait to read your report on how awesome they (surely will) sound...

[awkwardbydesign]

Second side veneered, but strangely a small split appeared near the top edge.  After a few hours it has lengthened to about 15"!  It hasn't been moved from a damp to dry environment (still in the same place), so not drying out.  Maybe I stretched it as I applied it?  I can fill it, but I need to know why it happened, and continued to lengthen over several hours, as i have another two sides to do.  Odd, never seen this before.

[wenig watt]

Every time you give wood a new shape, the stresses in the material change. the low tensile strength perpendicular to the grain then means sudden cracks.

Great work!

Best regards

Arndt

[ian]

Absolutely magnificent work!

[awkwardbydesign]

Every time you give wood a new shape, the stresses in the material change. the low tensile strength perpendicular to the grain then means sudden cracks.

But I have never experienced this with other curved panels.  I'm trying to understand what is different this time.
EDIT.  Unlike solid wood, it hasn't tried to return to a flat shape and cracked, it has pulled apart, torn in fact.  So the forces are acting along the curve, not lifting from it.  At least it appears to have stabilised now, and I just bought some beech wood stopper, so hopefully I can match the colour.

[Robert Young]

There are a few possible reasons why a crack like you've described may happen. Having suffered through this on a large veneering job for some acoustic reflectors at Zankel Hall in New York, where I was the design architect, I'm going to take a guess that your situation may be the same.

When the veneer is cut from the log, the outer surface is pushed together ever so slightly, whilst the surface in contact with the knife actually bends just a tiny bit to allow the knife to pass: think of the cut as a "peeling away:" the outside surface becomes concave, meaning the fibers are compressed, whereas the inner cut surface becomes convex, meaning the fibers are stretched. The result is tension stress: if the tension is too large, a very small crack, called (at least in the US) a knife check, will develop on the cut side of the veneer. This is usually so small that it can't be seen even with a magnifying glass, but it is there nonetheless. Veneer manufacturers call the compressed outer side the "tight side," and the stretched or knife-checked side the "loose side." This is important when specifying the application of the veneer (and where I made my mistake in the Zankel Hall project), as the "loose side" needs to be the glued side, to reduce the potential growth of the checks into something worse...

A few things can be done by the manufacturer to avoid knife checks, such as heating the log before cutting; having super-sharp knives; and utilizing a pressure bar to keep the veneer flatter as it is cut (avoiding the tension stresses). These basics are not always followed, though. Additionally, during drying, if the conditions are not proper, it is possible that normal shrinkage can accentuate the cracks, making them visible. Unfortunately, the first time these cracks do become visible is after the veneer has been applied and the finish cracks...

Any change in relative humidity that occurs while the substrate and the veneer are waiting to mate can impact the rate of change across the material. Plywood doesn't move much, thanks to the nature of opposing-grain plys. However, veneers do move a lot: as a rough rule of thumb, a 5% change in relative humidity over the course of a week can cause a .25% change in both veneer width or thickness. That is, a 20-cm wide pice of veneer will grow or shrink by .5 mm. This can happen to freshly-applied veneers when the tight side is the glue side.

I'm sure this is no consolation, but the work you've done so far is really beautiful, and I'm sure can be repaired given your mad skillz.

The problem at Zankel Hall was fixed by using a small amount of wood filler/putty to about 2/3 the depth of the crack. The remainder of depth was filled by applying a small amount of wood glue to the cured putty, then very lightly sanding the veneer across the crack, to deposit bits of the veneer dust into the glue until saturated. After fully drying, the area was sanded again, then finished. One can't see the repairs at all. Phew.

Hope this helps. Otherwise, never mind! 

[awkwardbydesign]

That's interesting.  How can I tell which side is which?  I have another two to do.  My panels are 40cm wide, and the longer crack opened to over 1mm in the middle.  I have filled them with beech coloured wood stopper, and it will do, although it isn't perfect.

[Chip]

I have filled them with beech coloured wood stopper, and it will do, although it isn't perfect.

Wood can be frustrating as it’s natural grain can cause mischief.  Robert’s suggestion of mixing veneer dust and glue works well.  By the time you apply a finish, you won’t see it, especially from 6 feet away.

Those cabinets are looking very nice indeed.  Keep up the good work.

[Robert Young]

did the pieces come with a slight curve to them, or were they flat?