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.
I love these wooden rings! But when Waiata Bespoke Jewellery (nga waiata as they were then) first got in touch and asked if I could engrave the backs of their chunky wooden rings with their logo, I wasn’t sure if I could do it.
Engraving on a curve
First of all, rings are cylindrical. Lasers need a flat surface to engrave. This is to maintain the right focal length for the laser beam for best results.
Secondly, the rings have such knobbly stones on them and nga waiata wanted to supply them made up rather than without the stones. How could we support them securely in the laser so they wouldn’t wobble or fall over during engraving? Any of these scenarios would be disastrous for engraving quality.
It’s amazing what you can do with Blu Tac! I use it all the time to support jobs on the machine. A nice big blob on the engraving bed floor held each ring securely, even although the stones are all different shapes.
My secret weapon
Now for the engraving. The text was small and fine and was to be centred in the middle of each ring back. I used my longest focal length lens which helps maintain focus better over curved surfaces. I also slowed the engraving speed down to maximise precision and minimise any wobble from the machine. This ensured crisply engraved letters, with a nice depth of engraving to give good visual impact in the chunky wood.
Yesterday, a customer asked me if I can make laser cut wood edges as black as possible as it would enhance her products. She wanted this even if it caused some charring on the surface which could be sanded off. No other customers had asked for this before. They just accepted that the edges would look as they came, and I would prepare them for what to expect.
The colour of a laser cut wooden edge is more to do with the colour of the wood used. A pale wood like birch or sycamore will have a lighter cut edge. Oak will be darker and mahogany darkest of all.
Best machine settings for laser cutting wood
The golden rule of laser cutting is to cut through cleanly in one pass as quickly as possible with a maximum of 90% power. This should minimise damage to the material and maximise product quality. If you cut more slowly than you need to, you don’t get a darker edge. You just get charring and flaming on the back of the wood. And it’s possible that the flaming could ignite the wood and cause a fire in the laser machine.
In this case, all the woods from plum to sycamore had quite dark laser cut edges. Kirsty makes wooden jewellery from the tiny shapes and sometimes paints them. You can find her as Hamespuns on Instagram.