Introduction: Make a Template for a Router and Bushing Cutout in Photoshop.
This template of a hop flower was made for a mash paddle Instructable but can be applied to just about anything that needs a decorative cutout or just a mortise, etc. I use Photoshop to make the graphic into a usable template. The same "resizing" I do in Photoshop can be easily done on paper without a computer though. All you need for this project is a router, bushings and bit to fit, clamps, paper, typical glue for paper, MDF or plywood and a couple of wood scraps.
Step 1: Determine Measurements and Print Out an Offset for the Template
The template I am making uses a router with a bushing installed and a bit at least as long as the wood is thick(3/4") The first thing to do when designing a template to figure out the "offset" from the bushing to the bit. Look through your bits and bushings to find a good combination. Usually, the smallest bit that meets the wood thickness requirement is best. Then select the smallest bushing that gives a safe clearance between the bushing and bit.
The formula for the offset is (bushing size - router bit size) / 2 = offset. The bushing I used is .4375". The bit was .25". The offset is .09375" (fraction is 3/32").
In Photoshop open or make a two tone graphic. This graphic of a hop is about as complex as you can get. Just remember that the router bushing is almost a 1/2" wide and the blade is a 1/4". Any tight inside corners might start to disappear when cut. Look at the hop stem in the test cut for instance.
-Note the resolution of your graphic. (From the menu Edit>Image size. There is field that tells resolution)
-Multiply resolution by the offset. Mine is 72 dpi x .09375 = 6.75. This is your pixel offset.
-With this graphic open and sized to the correct size you, select the white space. From the menu click Select>Modify>Expand. Put your "pixel offset number" in the dialog that comes up. It will expand the selected area. You can either fill the selected area or the inverse selected area with another color as I did here with red. Print this out.
Step 2: Glue It!
My most used methods of gluing almost always includes a paint roller or brush and a inking brayer. Put some glue in a tray or dish and get it all whipped up smooth and spread it evenly on the back of the paper or directly on the MDF/plywood board. Smooth the paper down onto the board and roll it a few times with the brayer. It is very important to get bubbles out and let it dry fully.
Step 3: Cut It! (the Template, That Is)
First make sure it is dry. Otherwise, the paper will come off while you are cutting.
Drill a few holes and cut out most of the way with a jig saw. A scroll saw would come i handy here but I don't have one. I had to resort to carefully cutting freehand it with a small bit on a router table (not recommended for a first time) and file to finish it up(recommended). The important thing is that the edges are uniform. When finished the paper can come up or carefully sanded off.
Step 4: Cut the Shape With a Router.
To set up the router, install the bit and bushing and keep it unplugged for now. Put the router on top of your template that is setting on a flat surface or on top of the wood you are going to test cut. Plunge the router until the bit barely touches the surface under the template and lock it in place. Next use your actual project piece or a piece you cut from it that is the same thickness to set the depth gauge. Now you know how deep you need to cut and you won't cut very far past what you need to. If you seem to come up short on the final cut depth, reset the depth gauge with the piece stacked with a business card. This will give you just a tad more of a cut depth.
It is highly recommended to try a new shape out on a scrap. It is possible that the shape needs to be altered.
Also when starting a cut that will go all the way through, use a scrap underneath. This may seem obvious but if you forget you will have to unclamp the template halfway through. It is very hard to get it to realign.
Here are some things to keep in mind if you are new to using a router.
The best method for cutting is very little by very little. Try to keep the plunge passes in 1/8" increments. Clean out the dust after each pass. The accumulated sawdust buildup from too deep of a plunge will burn junk onto the router bit. Router bits are pretty useless burned up and cleaning them up is a real pain. Also, pushing the router the wrong direction can cause the bit can get hung up and lunge in one direction. This is sometimes called climb. To avoid climbing keep your cuts shallow, cut clockwise when cutting on the inside of the shape. This means you are pushing in the same direction that the blade is cutting and against the force of any kickback. If you were cutting on the outside of a piece of wood you would work counter-clockwise. If this is confusing, just look at the direction the blade will be cutting into the wood and think of it as pushing a carving knife around the edge.
A good type of blade to use for cutting deep shapes is a spiral up-cut. These are nice because the slicing action pulls the router onto the wood and they can typically be found in longer lengths than other straight bits.