Spinning Knob Topped Handle for Threading Tap

I recently made a tap handle for use with small taps to make threaded holes for screws ( http://www.thingiverse.com/thing:844370 ). This is the same tap but with a knob at the top that spins so you can apply pressure with one hand and spin it with the other. The whole thing prints as one object.

Here is a video of it spinning (I'd use youtube if I could without giving up my phone number, but I can't): https://vid.me/bnQW

The way it works is that the knob is supported by a little 1mm diameter post which you can see in the cutaway views. When the print is done, you just twist the knob to snap that post and it will then spin freely.

You'll want to print pointy side down (I used a brim). You'll have to rotate this file 180 degrees in your slicer most likely. If you print it with the knob at the bottom, the entire weight of the handle will be supported only by a 1mm column of plastic.

Notes:
1-The source file is in FreeCAD native file format.
2-The square tap hole is 3.5mm which accounts for the side-ooze on my printer -- it fits my 2.8mm taps, but you may need to edit that for yours.
3-Also, the knob is sort of wobbly while printing. Mine came out fine despite that but you may want to decrease its mass by chopping the knob down.
4-Lastly, it occurred to me in the last print that it might print faster if the square hole for the tap was shorter and you just let the printer do a natural fill job. A 1cm depth would be more than ample. You could just add a cylinder to fill most of the extraneous square hole.