Roaddog Labs Bart Extruder Installation

From Roaddog Labs Docs

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing

Extruder Assembly

Required parts:

  • 1 x extruder body
  • 1 x extruder idler
  • 1 x hot end mount clip
  • 1 x 624zz bearing
  • 3 x M3 x 30 shcs
  • 3 x M3 washer
  • 5 x M4 x 20 shcs
  • 5 x M4 nut
  • 1 x NEMA 17 motor
  • 1 x MK7 extruder drive gear

MK7 to Motor

Attach the MK7 drive gear to the motor shaft. Ensure the set screw on the gear lines up with the flat on the motor shaft. Leave about 5 mm of the motor shaft exposed. We'll adjust the gear in a later step.

Attaching MK7 gear to motor shaft

Extruder Body to Motor

Attach the extruder body to the motor using M3 x 30 shcs and an M3 washer at each screw head. At this point only attache the 2 rear screws that aren't part of the idler assembly. Note how the motor is mounted so the cable will come off what will be the top of the extruder assembly.

Attaching extruder body to motor

Idler Assembly

Assemble the extruder idler by placing a 624zz bearing in the idler and securing it with an M4 x 20 shcs and M4 nut.

Assembling the extruder idler

Installing the Idler

Install the extruder idler using an M3 x 30 shcs and M3 washer at the screw head. The screw goes through the idler, acting also as a hinge and is secured into the motor.

Adding the extruder idler

Extruder Mounting

Attach the extruder assembly to the X carriage assembly. Use 4 M4 x 20 shcs and M4 nuts. insert the screws through the back of the X carriage.

Rear view of extruder mount

The M4 nuts fit into nut traps on the front of the extruder body. The upper left nut as you face the front extruder goes inside a cavity toward the rear of the part.

Front view of extruder mount

Hot End Assembly

Stock kits ship with an E3D Lite v6 and is assembled as shown below.

If your kit shipped with the optional E3D full v6 hot end follow the directions at this link

E3D Lite v6

Your Roaddog Labs Bart kit includes a genuine E3D brand V6Lite hot end. The assembly instructions here were derived from the E3D docs located at . The content is used under Commons Attribution 3.0 Unported license.

Required Parts

  • 1 x Stainless heatsink (Contains brass embedded bowden coupling ring pre-fitted in top)
  • 1 x Aluminium heater block​
  • 1 x Brass Nozzle (0.4mm)
  • 1 x 1 thermistor
  • 1 x 12v 25W Heater Cartridge
  • 1 x 12v 30x30x10mm fan
  • 1m of Thermistor wire (with connector)
  • 2 x 0.75mm Ferrules
  • 4 x Plastfast30 3.0mm x 16mm screws to attach the fan to the fan duct.
  • 1 x M3x3 socket dome screw and M3 washer to clamp thermistor.
  • 1 x M3x10 socket dome screw to clamp the heater block around the heater cartridge.
  • 1 x Fan Duct (usually red)
  • 1 x Small Black Plastic Collet
Cutting the sleeving to length. Sleeving on thermistor.

Cut the blue glass-fiber sleeving into 2 x 35mm lengths with wire cutters and slide one piece onto each of the thermistor legs. It is critical that during all assembly steps and during use that the blue sleeving covers the wire legs of the thermistor right up to the glass bead at all times. The glass fibre sleeving can start to fray if the cut ends are not treated with care, and once it starts to fray it is hard to recover, so do take care. If the sleeving becomes frayed the best thing to do is to trim off the frayed parts with wire cutters.

Thermistor bent into initial shape.

Holding the thermistor between your finger and thumb, with the legs held together, make a 90º bend in the legs about 5mm from the sleeving.

Thermistor inserted into block.

Insert the glass bead of the thermistor into the hole shown. Be sure to insert the thermistor into the hole that is not threaded. Fasten the thermistor in place using the smaller M3x3 screw and washer.

Screw on end of allen key.

It is helpful to place the small M3x3 screw onto the end of the supplied allen key and add the washer, the allen key can then be used to help insert the M3x2 screw into the threaded hole.

Thermistor being clamped into place.

The legs of the thermistor should go around the screw, one leg on each side. The washer should clamp down firmly onto the blue sleeving and partially cover the hole in which the glass bead is inserted. Use your fingernails to keep the sleeving under the washer whilst tightening.

Thermistor clamped into place.

It should look like this when clamped. Note the sleeving running right down into the hole.

The sleeving runs into the thermistor hole insulating it right down to the glass bead.

At this point it is worth taking a good look at your thermistor to ensure that everything is firm and secure. Visually check that the blue sleeving is insulating the legs of the thermistor right down to the bead. If the legs make electrical contact with the block or each other your temperature readings will be incorrect and you risk overheating.

Thermistor Wire
Stripped wire with heatshrink.

Strip 5mm of the ends of the thermistor cable and put a 15mm length of heatshrink over each wire.

Thermistor wires formed into hooks ready to crimp.

Place a ferrule on each sleeved thermistor leg, if you have the flared mouth of the ferrule pointing away from the hotend it makes it easier to push them over the wires later.

Wires alongside each other.

Arrange the wires of the thermistor and cable alongside each other so the ferrule can slide over the pair and hold them together.

Ferrule over bare portion of wires.

Push the ferrule over the bare portions of the wires ready to crimp into place.

Crushing the ferrule.

Crimp the ferrules by firmly crushing them with a pair of pliers. Squeeze hard to ensure a secure connection. You can use a fancy ferrule crimping tool if you have one, but it's not needed.

Heatshrink being shrunk.

Slide the heatshrink down over the now crushed ferrules and shrink into place with a heat source such as a soldering iron, hot air gun or even a flame.

Heater Cartridge
Heater inserted into block.

Insert the Heater Cartridge with the leads exiting the block the same side as the thermistor.​ Centre the cartridge in it's hole in the block. The ends of the heater will poke outside of either end of the block, this is normal and intentional.

Cable tie the thermistor wires to the heater cartridge wires so that they are secured such that the more delicate thermistor wires cannot be pulled away from the block.

HeaterBlock tightened around cartridge.

Tighten the clamping portion of the heater block around the heater cartridge with the longer M3x10 screw. As in the photo below you should be able to see slight bend of the heater block clamp as it wraps around the cartridge for maximum thermal contact. This is normal and intentional.


Nozzle screwed into block, and unscrewed a 1/2 turn.

Screw Nozzle into the Heater Block into the end closest to the thermistor holes. Be careful you use the same orientation as in the photograph. Unscrew the Nozzle a 1/4 to a 1/2 turn - You should see a very small gap between the hexagonal portion of the nozzle and the bottom face of the heater-block.


Screw the threaded portion of the heatsink into the top of the heater block until it butts up against the nozzle. The heatsink only needs to be screwed in hand-tight at this point, it will be tightened hot later.

Everything correctly assembled.
How NOT to assemble your hotend.

It is important that the nozzle and heatsink are correctly positioned with regards to the block as show in the images above. The second image is an incorrectly assembled hotend where the heater block is positioned too high and against the heatsink.


Collet about to go in.
Collet inserted.

Insert the small black collet into the top of the HeatSink, the side with the four small legs should push into the brass ring in the top of the heatsink with gentle finger pressure.

PTFE Tubing
PTFE Being cut with a sharp knife.

Cut the end of the PTFE that will be inserted into the hotend with a very sharp knife, a craft knife with razor sharp blade is recommended for this. Ensure that the cut end is square and flat after cutting.

PTFE Going in.

Insert the PTFE tubing into the top of the heatsink through the small black collet and slide it down through the heatsink as far as it will go.

PTFE Being locked into place.

The PTFE tubing must be held securely downwards without any ability to wiggle or move. To make the collet hold the tubing securely you must simultaneously push the PTFE tubing into the hotend while pulling up on the black collet, this will pre-tension the tubing and lock it into the downwards position.

PTFE Tubing, Guidance

The PTFE liner in Lite6 is an important part and crucial to the correct functioning of your hotend. Please ensure you follow the instructions below with care, instead of just shoving the tubing into the hole and blindly soldiering onwards.

  • The PTFE tubing is not optional, you must use the tubing or the HotEnd will not function properly.
  • The tubing should be inserted from the top of the now assembled hotend and pushed as far down into the hotend as possible at all times.
  • The end of the tubing that is inserted into the hotend must be cut cleanly and squarely with a razor
  • To release the tubing from the heatsink simply press down on the black collet in the top of heatsink while pulling on the tubing.

The PTFE guides the filament from the cold side of the heatsink right down into the hot nozzle. For it to do so effectively it must butt up against the nozzle squarely and be positively secured in that position.

Set the completed hot end assembly aside and move on to the next step. We'll return in the next section to wire and finish setting up the hot end.

Introduction | Bill of Materials |Frame Assembly |Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Validation and Testing | Working with Files and Printing