A couple of days ago, where I described the first stages of turning a PDF plan into an MDF template, we got as far as having a printed plan. Now let us turn that printed plan into a template we can use for routing the body shape.
The last step in the last episode was to double check all the measurements – well in my experience double checking is never enough. Stop what you’re doing and go and check it again.
First we need a piece of MDF. The recommended approach to doing this is to first make yourself a master template, and then use this to create a working copy of the template. For the master you’d use 9mm (because it is easier to work with and to sand to shape) and for the working copy 18mm (so you’ve got enough depth for the router bit to run against). Because this build is a one-off I’m just going to go straight to 18mm MDF.
Many people recommend gluing the paper template to the MDF, but I have previously had problems with the glue causing the plan to expand slightly as it dampened. I suspect you could overcome this problem using spray mount adhesive but I now choose a different approach. I tape the plan down to the MDF at four or five points and then hatch lines across the edge all the way round. Once the paper plan is removed it is a piece of cake to join the ends of the lines.
Then it is a matter of using a bandsaw or jigsaw to cut close to the line…
…and finish of by sanding to shape – continually checking against the paper plan.
A word of warning here. Spend time making sure the edges of the template are smooth and exactly as you want them to be. Don’t just look at the edges – close your eyes and feel them too. The first time I made a template I left a couple of bumps, knowing that I could tidy them up when I was sanding the final body. I quickly learned that a sanding job that would have taken a matter of minutes on thin MDF became a herculean task when I was doing it to 1.75″ of hardwood. Get the template right and you don’t have to do it later!
Now you’ve already checked the measurements three time but you know what… Do it again before you put the template anywhere near that chunk of expensive timber.