You’d assume that 3mm plywood is 3mm thick, wouldn’t you?
Wrong! With plywood, thicknesses are nominal, not actual. This is because plywood is made up of different layers glued together. 3mm usually has 3 layers, and the result is an actual thickness of 3.2-3.3mm. 4mm ply has another layer, and is usually 3.8mm thick.
Potential design disasters
This can create a whole worlds of pain for designers and manufacturers if they want to create products made up of pieces that slot into each other and require a good fit.
If you assume a thickness of 3mm and you design 3mm slots in artwork and then try to fit 3.3mm thick wood in the slot, it’s not going to happen. Or if 4mm ply were used, 3.8mm parts would be too loose.
Imagine making 300 reindeer kits for Christmas, sending the artwork to a maker, and getting back parts that don’t fit?
This could have happened to one of our earliest customers, but we made a prototype, realised the problem and fed it back to the customer. They tweaked the artwork before we performed the production run. This simple check saved our customer – and us too – a lot of time, money and heartache.
Always check that your designer and maker are speaking to each other to avoid disasters like this.