Saw this just now over at the other ww discussion group:
http://www.djmarks.com/stories/djm/Pattern_Routing_97352.asp
David Marks says:"Many woodworkers have commented on the number of templates I make. I will often hear humorous remarks like; “You must own stock in MDF” (medium density fiberboard) or “I’ll bet you have a warehouse somewhere to store all of your MDF patterns”. I have even heard one gentleman ask “Wouldn’t it be faster to just build the piece of furniture rather than spend all of that time making full scale drawings, mock ups, and templates?” My response was “Yes, but I’m not always happy with the outcome.”
"My methods are a system that I have developed from over thirty years of working with wood. I am meticulous by nature and I do not like wasting expensive hardwood, so as a result I have developed an approach to furniture making that makes sense to me. I always begin with sketches because it is the least expensive, quickest way to sort through ideas. If I see something I like, I develop it further. Once I decide to commit to a project, I will draw it full scale on a piece of 1/8” MDF in three views: Plan (Top), End, and Side. As I go through this exercise I’ll learn more about the piece thus preventing possible mistakes from occurring down the line. Another reason I make so many templates is the fact that I like to design pieces with curved lines and it is much more difficult to build woodwork with curves than woodwork that is composed of straight lines."
"A decent quality table saw with a sharp good quality carbide blade will yield lots of smooth straight cuts requiring little effort to scrape and sand smooth the various facets of a linear design. By contrast, a bookcase made from a dense wood like jatoba that has solid wood sides with elongated S curves, is somewhat of a chore to shape when it comes time to make two sides that are a mirror image of each other and finesse those curves."
"Pattern routing also known as silhouette cutting and template routing is a very efficient solution. For one thing, it is much easier to shape a piece of MDF than a piece of wood. If you have ever tried to smooth a curve in a piece of hardwood after it has been cut out on a band saw then you know what I am talking about. Wood has a grain structure to it and you will find the long grain fibers are easier to work with than the end grain. MDF is made from glue and compressed sawdust with no grain structure to it and you will find it is very easy to shape. After band sawing I’ll follow up with a pattern makers rasp and then fare the final curve with sandpaper. I find that the best way to blend the transitions is to double stick tape a piece of 80 grit sandpaper to a thin piece of wood 1/16” to 1/8” and work it back and forth leveling the high spots down to the low spots. Once the pattern or template is smooth, double stick tape it to the hardwood stock and band saw the profile staying at least 1/16 of an inch away from the template."
"After band sawing you can use a router with a flush trim bit to finish it off. The bearing will rub against your template while the cutter removes all of the excess wood flush to the edge of your template. Carbide bits work really well and for difficult woods I use a spiral or helical shaped carbide bit."
