Milling rough boards into 4 square lumber
When you go to your wood stores you are likely only able to get finished boards that is four square, meaning both edges and both faces are at 90° to each other. This is also why a 2x6 is actually 1-1/2" x 5-1/2 inches. Determine if the wood working plans you are using show the rough or finished sizes so you know if you need to adjust the dimensions.
Like all things you have to pay more for finished stock as opposed to rough stock. In same cases this can be significant. So it only makes sense to try and get lumber that is rough. This is lumber that is fresh off the mill. It has not been planed to a finished size and the surface isn't smooth like finished lumber.
Step 1: Cut your lumber to rough length
First thing to do is rough cut your lumber. There is no point in milling rough boards until you are ready to use it. It will remain more stable also. I generally cut the stock to length and make sure the ends are square. This is easiest to do with a miter saw and you will get the most accurate cut.
It is important for safety as well as aesthetics to remove and loose knots or cracks from your boards at this point as well.
Step 2: Planning one face flat
First thing to do at this point is to analyze the grain of the lumber to determine which way it goes. Anytime you plane wood you need to do this because if the grain is going into the wood you will likely get a rough finish and tear-out is more likely to occur. Also determine if there is any cupping of the board. By placing the cupped face down it will sit better on the jointer table and be easier to plane.
Set your jointer to remove only 1/32" at a time. This will make it easier to pass the boards through the cutter and your jointer will not have to work as hard. Keep making passes until the rough surface has been removed and the face is perfectly flat.
Step 3: Square an edge with the face
To make one of the edges square to the face I just planned I set the fence on the jointer so it is exactly 90° to the jointer table. Do not adjust the depth of the cut. In fact I never cut more then 1/32" at a time. Like before, determine which way the grain goes and feed the board so the grain rises out of the edge. Continue to pass the board through the jointer until all rough material has been removed. When you get a nice smooth edge check it with a combination square to see if it is square to the face.
Keep feeding the stock through checking after each pass with a speed square to make sure the edge is square to the first face you planed flat.
Step 4: Rip to the rough width
Over at the table saw to rip the board to its rough width. This dimension will be about 1/16" wider then the final dimension. Simply run the stock through the table saw and and then go back to the jointer to clean up the edge and remove any saw marks. You will need to run the board through twice to remove the 1/16" of waste.
Now your board should have two finished edges parallel to each other plus are square to one face.
Step 5: Planning the other face
The final step is to plane the final face flat and true and make it parallel to the first. This is best done using the thickness planer.
To plane the second face I use the thickness planer. It will plane down this face to my desired thickness and make it exactly parallel to the first face I planed on the jointer. I set my thickness planer to remove 1/16" at a time. It is important to measure your stock and determine the thickest point. Sometimes rough stock can vary in thickness and you shouldn't assume it is a specific thickness. Place the finished face down on the thickness planer table and continue to feed it through the planer until you achieve the thickness you need.
Conclusion:
The steps above outline how you can save money by buying rough stock and plane it into usable finished stock. This will not only save you money but will also give you the means to have lumber in sizes not provides by your local lumber store. Remember to check the woodworking plans you have to determine if the dimensions are rough or finished.
Always remember to read and follow the directions that come with your power tools. This will provide safety information as well as tips and techniques on how to use the tools more effectively.