Guide on removing a broken ABS filament inside the Prusa Nozzle MK2
This guide is aimed at Prusa i3 with the 2.85 mm Prusa Nozzle MK2.
So... the ABS filament has broken and a piece got stuck inside the nozzle, when trying to jerk the filament out of it. What to do next? Well this guide is describing a procedure that has worked for me. You may be ready for production again the very next day.
You need a 2.5 mm drill bit, a film canister made from HDPE, Acetone, a glass jar with lid, paper towels, a magnifier and off course the Prusa Nozzle MK2 dismantled from the machine. When using the drill bit inside the nozzle - be very gentle and use almost no force at all. It is good enough to turn the drill bit with your fingers at a slow pace. Measure how deep the drill bit can go in the nozzle on the outside first, to have an approximation on the safe depth without the drill bit damaging the 0.4 mm hole. Do not drop the drill bit inside the nozzle as it may leave marks on the surface!
1. Place the nozzle in the film canister and the film canister in the glass jar.
2. Top the film canister with Acetone almost all the way up to the edge.
3. Fill the nozzle with Acetone.
4. Close the glass jar with a lid.
5. Wait for the Acetone to penetrate the ABS plastic for 24 hours.
6. Use the drill bit between your fingers and drill the ABS plastic gently out of the nozzle( be very light and just use a small force).
7. Wipe the drill bit clean with paper towels.
8. Repeat step 6 and 7 until no more plastic comes out of the nozzle.
9. Fill the nozzle with Acetone and shake it with the fingers closing the holes.
10. Fill the nozzle one last time and let the Acetone pour slowly from the 0.4 mm hole by it self.
11. Empty the nozzle and wait a couple of minutes for the Acetone to disappear.
12. Inspect the nozzle by using a magnifier and look into the 2.85 mm hole in the direction of a bright light source(not the sun!) - it will be good enough to use a desk lamp.
Inspect the nozzle at various focal points inside the nozzle to be sure that there is no more plastic left. Use the reflections of the light inside the nozzle to be able to inspect the walls(it should be mirror finish).
There you are done and happy printing!
/Henrik