This is the Makerbot Smart Extruder that comes standard on the 5th generation Makerbot Replicator.

Here’s the front of the extruder with the fan guard removed. You can’t tell in this picture but the extruder casing is two parts held together by plastic tabs. The plastic tabs are very weak and break when you attempt to open the extruder.

The picture below that is the back of the extruder — the side that connects to the printer. The four circles on attached to the sides are magnets that hold the extruder on the printer.

The magnets are strong and hold the extruder to the printer pretty well and they make lining everything up easy. The first time you connect the extruder to the printer there is a software utility that is run that pulls the extruder in and makes sure its connected.

So what makes the smart extruder smart? Good question. One thing it does is understand when the filament runs out, pauses the the print and alerts you of the problem. Its a cool idea but 1) it rarely happens and 2) there are a lot of false positives when the filament gets stuck in various other parts of the printer.

The other smart things the extruder does include calibrating the printer bed and assisting in leveling of the bed. These functions work well but take forever — I’m talking more than 15 minutes. Its annoying enough that I would rather cross my fingers and hope the print bed was level than sit through the process.

Here is the inside of the extruder.

You may be asking, why are you taking it apart? It turns out that the main issue with the extruder is that filament breaks off inside the extruder all the time. At least once a week with daily printing.

This is the piece of the extruder that the filament usually breaks off in. Its the feeder to the hot end (not pictured above).

Specifically this little part in the bottom.