If you have a wooden interior door which has become warped through age or water damage, then you may decide to try and straighten it before you discard it completely. An older cabinet which has warped may bow either towards the ground, or to the side, but it can also be a twisted warp, in which the opposite ends of your wooden interior door turn away from the other. The latter is rather more difficult to fix.
Step 1 - Adjusting a Normal Warp
To adjust an ordinary warp, you need to remove the door using the drill, and then place it onto your work bench. Place a few small bricks onto the bench, and put the cabinet door onto the bricks with the bowed ends facing upwards in a u-shape. Place your board over the wooden interior door, and then put your concrete blocks onto the board. Leave for a week and then check the position of the bow.
Step 2 - Adjusting a Twisted Warp
Measure the door carefully, and purchase a truss rod to the right length. Insert the rod into one of the corners using a screw, and then add to the bottom in the same manner. The truss should be on the sides which are facing away from each other. Tighten this slowly by hand until the door is straight.