Stepstruder Mk6 Plus Assembly 1.75mm

If you are upgrading a MakerBot Plastruder MK5 to a MakerBot Stepstruder MK6 using the MakerBot Stepstruder MK6 Upgrade Kit, proceed to the Stepstruder MK6 1.75mm Upgrade Instructions. Otherwise, continue below.

Tools You'll Need


The Stepstruder MK6 goes together pretty easily, but you'll need a few tools to speed the process along:

  • Scissors
  • 1.5mm Hex Wrench
  • 2.5mm Hex Wrench
  • 13mm Wrench
  • Adjustable Wrench
  • Two Pliers
  • Soldering Iron
  • Sharp Knife
  • Tape

Strongly suggested

Parts You'll Need

Nuts and Bolts


Custom Machined Parts


MK6 Nozzle


MK6+ Thermal Core


MK6 Thermal Barrier


Laser-cut Parts


High Torque NEMA17 Stepper Motor


Hookup Wires


Heater Cartridge



This is not included in the extruder box. The Thermocouple comes packed in a white wax paper envelope that is included in the Gen4 electronics kit, in the ziplock bag with the 6 pin IDC heads and rainbow cables.


PTFE Tubing

Note 4/2011: The liner tubes are now shipped crimped together, and with an optimized tip angle. Install them together and trim the excess normally.


Anti-seize Paste, Heat Sink, Ceramic Tape


Heat Shrink Tubing




Part List

Prep Work

Peel off protective coverings.

The acrylic parts come with a protective paper film that covers the surface. Use your fingernail or a small screwdriver to remove this film.

Filament Drive System

Add Plate A to stack.

Take Plate A and place it in front of you as shown in the picture.

Add Plate B to stack.

Find Plate B and place it over Plate A as shown.

Add Plate C to stack.

Plate C is two pieces of 2.3mm Black Delrin. Place plate C onto the stack as shown. Pay careful attention to the orientation of the parts.

Add nuts to Plate C.

Add four nuts to Plate C as shown.

Add Plate D to stack.

Plate D is the top of the sandwich. Place it on the stack as shown.

Bolt stack together.

Insert M3x25 bolts

Insert four M3x25 bolts into the holes as shown. These are for securing the motor. In this step they help keep the layers aligned.


Insert M3x22 bolts

Insert two M3x22 bolts as shown.


Hand tighten nuts onto the M3x22 bolts. (Do not tighten nuts to M3x25 bolts.)


Tape nuts on filament drive housing.

Place an M3 nut into each of the four holes and tape into place as show.

Attach drive gear to motor shaft.

Bolt the gear onto the motor shaft as shown. The bottom of the drive gear should be 4.9 mm from the top of the motor. Use an M5 bolt to set the height of the drive gear as shown. Ensure the set screw contacts the flat part of the shaft.

Fan mount assembly

Remove the fan connector

Using wire clippers clip off the fan connector as shown.

Strip the wires

Strip the ends of the fan wires and the black/red cable.

Add heat shrink

Place 1 inch of large heat shrink around both fan wires and 1 inch of small heat shrink around the black fan wire as shown.

Solder wires

Ensure the heat shrink is a few inches from the cable ends. Solder the fan wires to 24 inches of black/red wire as shown.

Shrink the heat shrink

Place the small heat shrink tube over the solder joint and heat as shown.
Place the large heat shrink over both solder joints and heat as shown.

Mount the fan to the bracket

Using two M3x16 bolts, two M3 nuts, and two M3 washers bolt the fan to the bracket as shown. Ensure the fan cable is oriented as shown. Ensure the fan label is facing the inside of the bracket.

Bolt motor to filament drive housing.

Add the motor

Place the motor on a flat surface. Ensure the wires are to your left when facing the motor.

Add the fan mount

Place the fan mount on the motor as shown.

Add cork gasket

Place the cork gasket as shown.

Add drive housing

Place the filament drive housing as shown.

Tighten bolts

First, let's check the alignment of the pulley. Hold your motor assembly in place as shown and compare its position to the black delrin layer. The cork gasket will compress a bit, so remember to allow for that.

Tighten the bolts evenly. Do not over-tighten or you run the risk of cracking the acrylic or stripping the bolts holding the motor's body together. The cork gasket should be evenly compressed on all sides as shown.
Tighten the bolts such that the drive gear is symmetric in the filament slot as shown.

Pre-load all the t-slots with nuts.

By doing this before the assembly, you will save yourself countless trips to the floor to find dropped nuts, and other headaches. We use a simple three-step process:

1: Tape to "top" side of the acrylic


2: Flip it, and insert nuts into the slots


3: Tape over the nut


Attach supports to one arch.

The supports are two of the same part. The tabs are asymmetrical though, so make sure the bottoms of the supports are flush with the bottoms of the tabs as shown. Tighten the bolts to finger tight for now.

Attach other side to supports.

Take the other support and attach it on the back side. Tighten the bolts to finger tight only.

Attach top to supports.

The top plate will bolt onto the arches as shown. Bolt it into plates and only finger tighten the bolts.

Attach bottom to supports.

The bottom parts bolt onto the arches as shown. The hex nut cutouts are slightly off-center for mounting purposes. Make sure you keep them on the same side. You will also want to ensure that a line drawn through the hex cutouts will pass through the large circular cutout in the top plate. This is where the filament path goes, and we want it to be in-line with the mounting holes.

M3x40 bolts into top piece.

These bolts are how the hot end is attached to the filament drive mechanism. Drop them into place as shown.

1" spacers + nuts to bolts.

These spacers will ensure that the hot end is separated properly from the filament drive mechanism. Put one spacer on each bolt and then thread a nut onto it. Feel free to tighten the nut to 1/4 turn past finger tight.

Attach filament drive to support.

The tabs on the filament drive ensure that you can only bolt the filament drive in the proper orientation. Insert it into the slots and then bolt it in place. Tighten the bolts to 1/4 turn past finger tight with the hex wrench. This is also a good time to tighten the rest of the bolts to 1/4 turn past finger tight as well.

Superglue spacer feet to support.

Using superglue, or ideally acrylic cement, you'll want to attach the spacer feet to the bottom of the supports. Make sure the hole in the spacer lines up with the hex cutout or you'll be in for a grumpy surprise. If you're using superglue, its a good idea to scratch up the surfaces to be glued for better adhesion.

Tape M5 nuts into spacer

Once the glue has dried, you'll want to insert the M5 nuts into the cutouts. Tape over these nuts to keep them from falling out during the rest of the assembly process and during usage.

New, Easier Cartridge-based Hot End Assembly

Apply anti-seize to threads.

If you ever plan on disassembling your hot end, it's imperative to apply the included anti-seize compound to the threads. This stuff will protect against rust, corrosion, seizing, and galling that can happen at high temperatures. Simply smear a bit on your finger or a swab and apply it to the external threads. It should be applied to the nozzle threads and the thermal barrier tube threads.


Bolt nozzle into thermal core.

To bolt the nozzle in all the way, get an adjustable wrench and your 13mm wrench. Screw the nozzle all the way into the thermal core by hand. Tighten them against each other with the wrenches. Use the 13mm wrench on the nozzle, and the adjustable wrench on the flat parts of the heater core.


Thread in thermal barrier tube.

The thermal barrier tube is what provides the structural support for the PTFE as well as keeps the heat from travelling all the way up to the filament drive mechanism. Apply the anti-seize and screw it all the way into the heater core. There isn't much to grip on, so just make sure you tighten it as much as possible with your fingers.


Insert and trim the PTFE Tubing

Insert the small diameter PTFE tube into the larger PTFE tube as shown


Insert the PTFE tube into the thermal barrier tube with the pointed end at the nozzle. Ensure the PTFE tube is pushed all the way into the nozzle.

If you're having trouble fitting the PTFE insert into the tube, put your PTFE barrel into the freezer for 15 minutes or so. The PTFE will shrink and slip in easily.


Using a razor knife trim the PTFE tube so that it's flush with the top of the thermal barrier tube as shown.


Put the heater cartridge in place.

  • Be very careful handling the cartridge heater and wire lead. They are delicate and can be broken if stressed, bent, or pulled at the joint. *

The heater cartridge should slide easily into the hole we've had precision-milled into the aluminum hot end. Put it right in the middle like this; the ends will stick out a bit.


Now lock in in place with the M3 x 4mm set screw. It will be the shorter of the two bolts in the MK6+ kit. Tighten down about a third to half turn past finger-tight.


And here we are with our heater in place. Wasn't that easy?


Attach thermocouple

Use the thermocouple included in your Extruder Controller v3.6 kit. This is the long, brownish wire with a metal tip on one end, and red/yellow wires on the other end. Attaching it to your hot end is very easy: we will be bolting it to the side of the MK6 thermal core.

Ensure that you use a layer or two of Kapton tape wrapped around the thermocouple end to electrically isolate the thermocouple from the metal extruder body (Picture does not show the Kapton tape isolation).

To attach it, use the M3 x 6mm bolt included in the MK6+ kit, along with a M3 washer. Thread the bolt into the tapped hole and tighten the thermocouple under the washer. You'll need to keep it in place as you tighten as it has a tendency to be pushed out before getting clamped down. It's a good idea to wrap the thermocouple lead around the block as we've done here, so both leads come off the same side of the heater block.

If you find that the tapped hole isn't quite deep enough, just add another M3 washer.


And here we are, both heater and thermocouple installed.


Insulate the thermal core.

The video below was intended for the MK5, but is relevant to the MK6 as well.

Prepare the ceramic tape

Cut one length of ceramic tape 70 mm long.


Mark the center


Use the thermal tube to press a hole in the ceramic tape.


Your result should look like this


Mark the center of the longer piece of ceramic tape


Use the thermal tube to punch a hole through the longer piece.


You now have two pieces that look like this.


Slide the two strips onto the thermal tube.

They should go on perpendicular to each other. Then wrap them around the heater — most of the assembly should be covered by insulation.


Now wrap it with some tape to hold it in place and insulate further.


Slit the insulation and thread the bolts in.

Make a slit for each of the four bolt holes, and then thread a bolt into the tapped hole.


Here we've threaded the first of the four bolts. I just use one bolt for this part. Right now, you just need to ensure that the slits are in the right position.


Install the heatsink and retainer plate.

Put the bolts through the holes in the retainer plate and then screw them into the thermal core. You might need to give the heat sink a squeeze with some pliers to get it to hold on to the tube. Let it sit right on top of the retainer plate.

Some of these pictures show the heatsink below the retainer plate; this is an error which we are working to correct.

Next, put the 4 M3 x 25mm bolts through the holes in the retainer plate, and then thread all four into their tapped holes.


Attach the hot end to acrylic assembly.

Mounting MK6+ is slightly different than the MK5 and MK6 — there will be a slight space between the retainer plate and the nuts that hold the 1" spacers in place. First, tighten the nuts down against the spacers:


Next, put the thermostat from the safety cutoff kit in place.

Note: DO NOT run a cartridge-based hot end without a Safety Cutoff Kit. The cartridges will reach much higher temperatures than our previous heater systems.


Now, fit the four bolts through the holes in the retainer plate and tighten down nuts against the plate. The retainer plate will flex slightly and act as a spring. This will keep enough pressure on the nuts so they stay in place.


If necessary, slide down the nut over the thermostat to hold it in place against the retainer plate. The thermostat should be in contact with the plate.


Completed Stepstruder MK6+

All done! Now put your feet up and grab a beverage. I mean keep building! Yes.

Unless otherwise stated, the content of this page is licensed under GNU Free Documentation License.