Walnut veneer edge chip-out – advice appreciated
We’re fairly new to veneering and it’s become obvious there’s a lot more to it than we first thought.
We’re wrapping paper-backed walnut veneer around the perimeter of an MDF platform (includes R24 curved corners) and trying to make the process repeatable. At the moment we’re struggling with chip-out when trimming the veneer flush.
Current process:
Paper-backed walnut veneer
Veneer lightly misted to help it bend around curves
Using cold press veneer glue
Clamped with cauls and a ratchet strap (moderate pressure)
Left to fully cure
Trimming flush with a handheld router
Solid carbide down-cut spiral bit
Taking light passes (~0.3mm per pass)
Despite this, we’re still getting random chip-out on the walnut edges.
We’re trying to work out what the main cause is — moisture, glue type, clamping pressure, router stability, or just walnut being unforgiving.
Our goal is to make this a clean, repeatable process without having to rely on heavy sanding to hide defects.
Any advice from people with more veneering experience would be genuinely appreciated — we’re definitely still learning.

I suspect the chipped areas are in "end grain" mdf. Glue can soak into the edge of MDF that can cause a poor bond. You can apply glue to the edge grain MDF beforehand.
I have made up an edge trimming knife holder to trim veneer edges. Ulmia and other companies sell them that use utility knife or razor blades to cut flush or just proud of and edge. It is a much gentler process than a router bit. You will have problems with turning the radius corners with one.
Band clamps are not ideal for applying even pressure for veneering. Ideally you would want to vacuum bag this but you really need to think through the set up. I assume your box is open on the one face. Just vacuum bagging would distort or destroy the box. You would have to use an internal bag to stabilize the pressure in the internal cavity. Ther would be a few trials before you get the process right.
Another alternative is to iron veneer this. You apply PVA to the substrate and veneer and let them mostly dry. Then when the glue is dry to touch use an iron to reactivate the adhesive and press the veneer down with a block of softwood. Work slowly around the work piece. It is effective and I have had pieces done this way that have held up for decades. Choice of Pva is crucial. Some will not heat reactivate. Try some tests. You want an iron setting that is only hot enough to reactivate. Too hot and the veneer can be damaged and the glue will deteriorate. Take care at the corners to work evenly around the radius to ensure no buckling of the veneer.