Start with a horizontal line - the knife will be on this line where the blade flows into the handle and can fall below it anywhere but should not rise above it.
1. Draw your knife to scale; sketching in where the blade will be when it is both open and closed.
- the length left for the tang should be approximately the same as the depth of the handle at this point - draw a circle here and the centre of the circle is the blade pivot point
- mark out a further 70mm on the handle to show approximately where the blade will go when folded - a further section will be needed to secure the end of the spring (at least 10mm)
2. Draw on the position of the spring
- the middle pin should be around two thirds of the way along the knife
- at the tip, the spring needs to be 3mm deep
- at the middle pin, the spring needs to be 6mm deep
- the end of the spring needs to be large enough to give the knife stability and take the end hole
Here you can see knife designer Jeff Durber developing sketches for a knife with Grace and Nicola:
