Add a Spline to Hardwood Flooring
Lay the hardwood flooring normally, until you wish to change the direction of the flooring. At the point of change, lay the flooring so that both groove sides of the tongue and groove system are back to back to each other. This creates an opening between the two pieces of hardwood flooring.
Spline the two pieces of hardwood flooring together. To do this, purchase a spline, or create one using a piece of hardwood. Sand down the hardwood to fit snuggly between the two pieces of hardwood flooring. The spline needs to fit tightly, but not so tight to cause any ripple or change in the positioning of the floor when the two pieces are put together.
Insert the spline into each of the groove openings to be sure there is a tight fit. Place the two pieces of flooring next to each other to be sure they fit flush against each other. Be sure to create a properly aligned angle to create the design you need with the hardwood flooring.
Glue the spline into place by inserting a small amount of flooring glue into the groves. Then, insert the spline into place and push the two pieces of flooring together. Wipe away any excess glue and align the flooring to create the new pattern, as you would like.
Finish laying the hardwood flooring in the new direction.