I have been doing a lot more router work of late, but in the past, all my work has been ‘stand-alone’ in as much as the shaped parts were not having to mate with other shaped parts.
I have had a lot of success routing with 6mm MDF as my preferred template option as it requires little work to shape.
My current project however requires three curved pieces to nest into each other and I am having the devil of a job getting them to match up. I am using bearing-guided bits, cutting a kerf with the standard bit, then re-cutting a new template from the old negative template with a bearing three times the size of the bit. On small stuff, it works really well.
After a frustrating day, where templates would just about match up, I realised that the problem was probably flex in the materiel. Even though the templates are 80mm (about 3 inches) across, there was a bit of flex. They are 1500mm (about 5 feet) long. Not helped by using 4mm when I ran out of 6mm…
So before I go out and buy more MDF, what thickness would you use for this template? I’d prefer the minimum wastage, and as the parts are quite large, I can only get four out of a full sheet. Price is not a consideration. Will 9mm do, or should I go the whole hog and use 12, or even 18mm?
Would you use another sheet good?