Step 1
Mark the intended position of the drain at the bottom of the plastic tub. Use a pencil to create an \"X\" that indicates the center of hole through which the drain assembly will be placed.
Step 2
Measure the diameter of the drain assembly. Place calipers around the drain assembly's shank. Transfer the measurement to a tape measure to determine the diameter of the drain assembly's shank. Select a hole saw equivalent in diameter to the shank of your drain assembly. Attach the hole saw to a drill, place the hole saw's pilot bit at the center of the \"X\" mark and drill a hole through the plastic tub.
Step 3
Deburr and clean the freshly cut hole using an emory cloth and a lint-free cloth. Pull large chunks from the hole’s perimeter using your fingers. Sand and remove burrs by rubbing the hole's perimeter with an emory cloth, and remove dust and small particles from the area by wiping it with a lint-free cloth.
Step 4
Place a bead of plumber's putty on the underside of the sink assembly's strainer. To create a bead of plumber's putty, roll a portion of the putty on a flat surface until it forms a long, thick thread. Try to create a piece of \"spaghetti\" approximately ?-inch thick. Wrap the bead around the underside of the strainer's flange, pinch off the excess putty and join the cut ends by smoothing them with your fingers.
Step 5
Place the drain assembly's shank through the hole created in step 2. Hold it in place, and attach gaskets and nuts to the shank's threads. Turn the nut clockwise to tighten it. Continue to tighten the nut while keeping an eye on the putty to make sure it remains on the underside of the strainer's flange. Tighten the nut until the flange tightly fits against the tub's surface and the excess putty oozes out around its perimeter.
Step 6
Remove excess putty with a lint-free cloth, and smooth the remaining putty with a moistened finger.