Filament Hole Reamer

I like making boxes with a filament hinge. I make the hole for the filament usually 2.2mm diameter - with printer tolerance, this usually gives a finished hole of about 1.8mm. It is not possible to use support inside a hole this small, and often the design will not permit the hole to be printed vertically. So, you end up with a hole that is not perfectly shaped inside to accept the filament smoothly.

I designed this tool to be able to reach all the way through even the deepest holes of any of my designs.

I made it with ABS because I thought it would need the strength, but PLA would likely work as well.

Assembly Instructions

Requires a metal coat hanger that measures about 1.88mm diameter.

Cut off a piece about 230mm (9") long. Bend one end around into a loop (doesn't need to be pretty, just fit into the notched area on the shaft part).

Slide the wire into the shaft (if it is too tight, you may need a reamer to make the reamer - HA!). 

Push it in as far as you can - no more than 1-2mm above flush. 

Screw the butt end on. I recommend using a grinder or file to form the end into a somewhat flat, sharp tip.

If it doesn't cut/remove the plastic from your filament hole, consider hammering it a little to widen the blade - remember to re-sharpen afterward.

How to Use

Gently push it into the hole, twisting around a little one way and back again. Keep gently, but firmly pushing and twisting until you have cleared the entire length. Be patient as it is possible to break the hinge hole with too much force. Consider only inserting half way from one side, then repeating the other half from the opposite direction. Test fit often with a piece of the hinge filament to know when it is done.