With draft, you file a slight angle on the metal piece being inlet into the wood so that it will fit without binding. You are basically making the bottom of the piece slightly smaller (dimensionally) than the top. It is very important that you maintain the shape of the piece on the surface while filing, otherwise, a gap will form. File from the bottom of the piece towards the top edge; trying to maintain an angle of abut 2-3 degrees (it don't take much).
Notice that the line I drew at the spot marked "DRAFT" is not at 90 degrees perpendicular to the top of the tang. In most instances, this slight angle should be enough draft to allow the piece to go in and out of the inlet without binding or splintering the wood. Notice that the line I drew at the spot marked "PLENTY OF DRAFT" is much steeper and even farther out of 90 degrees perpendicular to the top of the tang. The degree of the angle may vary, but will always be radically steeper than the draft you put on parts that go straight into and/or out of an inlet. The steep angle at the area I marked "PLENTY OF DRAFT" is key to getting a gapless fit at the stick end of the lollipop.
I find it easier to file a normal draft in all along the edge of the lollipop first, then mark your inlet wth a marking knife or a sharp Exacto knife. Once you get the excavation for the lollipop started, then you can start steepening the angle at the front and front sides (only) of the lollipop. As others have said, it's a painstaking, trial & fit, process that should not be rushed. Once again, resist with all your might the urge to remove any major wood at the front of the inlet. Instead, file a hair more off the front & front sides of the lollipop. You will swear that the tang will never drop into place; then suddenly it does. Remember that the tang is not only moving down, but also back as it approaches it's final position.
