Plastruder MK5 Build Instructions

Estimated Build Time: 3 hours

Tools You'll Need


The Plastruder MK5 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
  • Pliers
  • Soldering Iron
  • Sharp Knife
  • Tape

Strongly suggested

Available Tutorial Videos

Parts You'll Need

The Plastruder MK5 comes with all the parts you need in order to build the extruder. Depending on what electronics you have, you may need some additional parts. For example, with the Gen3 electronics it's recommended to use a Thermistor and a Relay Board Kit for temperature measurement and driving the heater, respectively.

Nuts and Bolts


Custom Machined Parts


MK5 Nozzle


MK5 Thermal Core


MK5 Thermal Barrier


Laser-cut Parts


DC Gearmotor


Hookup Wires


Power Resistors


PTFE Tubing


606 Bearing


Anti-sieze 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. You'll want to peel it off before you begin assembly. Use your fingernail or a small screwdriver to help peel it off.

Attach thumb wheels.

Included in the kit are some thumb screw covers for the M5 bolts. This allows you to adjust the bolts without a hex wrench. These are press-fit which means they must be 'smashed' onto the M5 heads. The simplest DIY method we've found is to use two pliers as shown below.

You should only put a thumbscrew on one of the M5 bolts included in the kit; if you have a longer M5x20mm bolt, put it on that one. Thumbscrews on the M5 bolts which hold down the extruder can potentially run into the bolt heads on some platforms. The one bolt with the thumbscrew is used to apply pressure to the delrin plunger.

Tape all nut slots.

A recent innovation in the T-slot Style Captive Nut Technique is to pre-load all the t-slots with nuts. This is accomplished by taping the nut into the slot so it cannot fall out. 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:

Do this to all the parts with T-slots, except for the A and D pieces. We'll tape those parts later after it's been assembled.

1: Tape to "top" side of the acrylic


2: Flip it, and insert nuts into the slots


3: Tape over the nut


Filament Drive System

Insert M3x22 bolts into Plate A.

Take Plate A and hold it upside down. Insert bolts into the holes as shown. Gripping it by the bolts, flip it over and lay it bolt-heads down. The rest of the filament drive will be built by stacking up layers on top of this part.

Add Plate B to stack.

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

Add Plate C to stack.

Plate C comes in three parts and is made from Delrin. Place the various layers onto the stack as shown. Pay careful attention to the orientation of the parts.

Add nuts to Plate C.

There is a spot for some captive nuts on Plate C. This is where you can mount a Magnetic Rotary Encoder if you like. Take this opportunity to insert the nuts for later use.

Add Plate D to stack.

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

Bolt stack together.

Now that the stack is complete, lightly bolt it all together. We still need to work on it, so don't tighten it down with a hex wrench yet. The nuts should be finger tight.

Insert plunger.

The plunger is what presses the filament against the drive gear. It should slide into the space in Plate C as shown.

Insert thumbscrew + nut

The thumbscrew and nut are what pushes on the plunger and applies pressure. They are held in by two retainer bolts (next step). Plates B, C, and D are sized so that the hex nuts will fit just right. Two of the points on the hexagonal nut should go in the grooves in Plate C. This is more easily accomplished by threading the nut on the bolt and putting it in as one piece, as shown in the picture.

Attach thumbscrew retainer bolts.

The thumbscrew retainer bolts are what keep the M5 nut in place, and need to be on the outside of the nut as shown. Insert them in and then bolt them in place. Tighten finger-tight for now though.

Attach drive gear to motor shaft.

The drive gear is what grips the filament and pushes it down into the hot end. Bolt the gear onto the motor shaft as shown. It should be just touching the top of the motor. Make sure you position the set screw so it is pressing into the flat part of the shaft. This will ensure the maximum grip.

Attach bearing to motor shaft.

Put the 606 bearing over the motor shaft as shown. Depending on the motor this may be easy or a bit difficult. Give it a little tap if it is being a grump.

Bolt motor to filament drive housing.

Now that the filament drive housing is complete, its time to bolt the motor on. Take four M3x22 socket cap screws and put them in the remaining holes. From the opposite side, press the motor assembly into the large middle hole. The fit may be a little tight, so make sure when you press it in that you have the motor vertically aligned to the filament housing. If you are off-axis it will make it difficult, and there's a chance you'll crack the acrylic. Take it easy, and if it doesn't fit well, just sand the holes a little. If it's very tight you might need to take the 606 bearing off of the motor shaft and insert it from the other side; make sure the items line up correctly.

Once the motor is bolted on, it's time to tighten the rest of the bolts. Use pliers to grip the nuts while you tighten the bolts. Only do about 1/4- to 1/3-turn past finger tight. If you tighten it much further, you risk breaking the acrylic.

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.

Tape nuts on filament drive housing.

Now it's time to insert and tape the nuts into place for mounting the filament drive mechanism to the supports. Tape them into both sides. (Ignore the broken tab from my Hulk-like strength.)

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. I like to tape over these nuts to keep them from falling out during the rest of the assembly process and during usage.

Hot End Assembly

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.


Apply anti-sieze to threads.

If you ever plan on disassembling your hot end, it's imperative to apply the included anti-sieze 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.

Note: Pay attention to the orientation of the thermal core. The four mounting holes should be on the side of the barrier tube, and the single threaded hole on the side of the thermal core should be towards the side with the nozzle.

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-sieze 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 PTFE tube into assembly and trim.

The PTFE tubes now ship with a chamfered end. This allows the tube to sit further inside the nozzle and maintain a better wall alignment with the inside 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.


How to chamfer your PTFE tube.

If you do not have a chamfered PTFE tube and want one, it's as simple as slowly (and carefully) sharpening the tube with a pencil sharpener. The cut does not have to be flawless because any angle will fit better than no angle, and after repeated heating cycles the tube will slowly expand to fit snugly inside the nozzle.

Insert and trim the PTFE Tubing

The heater core is tapped all the way though. That means the thermal barrier tube will thread all the way down until it is touching the nozzle. Both of them have a 1/4" inner diameter bore that matches the 1/4" outer diameter of the PTFE tubing. Insert the PTFE tubing into the thermal barrier tube and make sure it extends all the way into the nozzle. Once it's pushed all the way down, you'll want to trim it so that it's flush with the top of the thermal barrier tube. The easiest way to do this is with a sharp knife.

Note: The fully inserted PTFE tubing should extend roughly to where the hex starts becoming a cone. It's a good idea to pull the PTFE out and do a sanity check before slicing it off.


PTFE tubing must be inserted all the way

This cutaway drawing shows the full insertion of the PTFE tube. Note that it extends all the way into the nozzle. You can check this by pulling it out and measuring it (should be roughly 80mm) or by unscrewing the nozzle with the PTFE tube in place.


Bolt on power resistors.

The power resistors are the heating element for the hot end and should read 5 Ohm (5Ω). Pay extra attention to the markings on this element as customers who have accidentally grabbed a similar but incorrect power resistor have had a hard time discovering this issue after properly wrapping their hotend. Use the provided tiny M2 bolts to attach them to either side of the thermal core. Tighten them down with the hex wrench.

Connect Teflon Wires onto Power Resistors

Provided in the kit is a short length of PTFE insulated wire. This slippery bit of wire is capable of handling higher temperatures than your average bit of insulated wire. We'll be using it to wire the resistors together in a safe way.

First, cut the wire into two equal halves. The PTFE is rather difficult to strip with standard wire strippers, so get your sharp knife back out. Strip both ends of the wire, and insert it into its proper place as shown in the picture. Mark where the middle of the wire goes through one of the second resistor and then remove the PTFE covering the wire in that area.

The resistors themselves are 5 ohm resistors and we are going to wire them in parallel. The total resistance will be 2.5 ohms. This will be run at roughly 12v for a 57.6-watt heater. Since the new hot end has quite a bit more material to it, we need the higher heating capacity to make it operate. That is why you need a relay if you are using the Gen3 electronics.

Clip through both the legs of each resistor


Bend the clipped parts to the side a bit, so they will not get stuck on each other when closed.


Bend the end of the Teflon-coated wire to form a loop.


Place the loop in the end of the resistor.


Squeeze the sides of the resistor leg to crimp them.

You will have to play with this a bit to get a solid mechanical hold. Repeat these steps for each connection. You can even add a bit of solder to the joints when you're done.

It is a good idea to use high-temperature,silver-bearing solder. The resistors will be getting up to at least 220°C, and probably higher. Normal leaded solder (64/40 or 63/37 tin/lead ratio) will become molten at this temperature (it melts at 183°C). We've used normal solder for a couple hundred hours, but it does get rather oxidized, and it's not ideal. If you use silver-bearing/ROHS solder it will have a higher melting point and last longer — 96.5% tin/3.5% silver melts at 221°C. You can also use plumbing solder that is 95% tin/5% antimony, which melts at 235°C. If you do, make sure to apply a small dab of non-acid paste flux, as plumbing solder often doesn't have rosin-core flux like electronics solder does. Its' not a major problem though; the worst that could happen is that you lose a connection and need to re-solder.


When you're done, you can solder the same wire in two different places and have a much nicer connection.


Cut the black and red wire into two 24 inch pieces

One piece is for the extruder heater, one for the motor.

Solder red/black wire onto PTFE wires.

From the PTFE wire, we can use standard red/black wire to handle the rest of the path to the MOSFET or the relay. Simply solder one of each wire to one of the PTFE wires.

Solder the red/black wire to the motor wires

If you're going to use heat shrink tubing, make sure you place one inch long pieces on each wire before soldering. This way, after you've soldered your connections, simply slide each piece into place, heat, and they'll shrink over the connections.

Insulate wires.

Starting January 1st, 2011, Plastruder MK5 Kits will now include two sizes of heat shrink tubing. This will now be the preferred method for insulating soldered connections.

Other options include Kapton or electrical tape.

Prepare thermistor (Gen3 only).

If you are using Gen3 electronics, you will need to use a thermistor for temperature measurement. Prepare the thermistor as in the instructions for the Plastruder MK4

Attach thermistor (Gen3 only).

If you are using Gen3 electronics, you will need to use a thermistor for temperature measurement. This can simply be taped over the threaded hole on the face of the thermal core (where a Gen4 thermocouple gets mounted). Use multiple strips of Kapton to make sure you get a solid contact for the thermistor.

Attach thermocouple (Gen4 only).

If you are using Gen4 electronics, you will want to 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 MK5 thermal core.

First, wrap the tip of the thermocouple with a small piece of kapton tape to isolate it electrically.

Then, to attach it, take out your M2x5 bolt, and your M2 washer. Thread the bolt into the hole, and when you're about halfway down, put the metal end of the thermocouple between the washer and the heater core. Continue tightening the M2 bolt until the thermocouple is securely attached. You'll need to keep it in place as you tighten as it has a tendency to be pushed out before getting clamped down.

If the threaded hole is not quite deep enough for the M2 bolt, you can take an M3 nut and use it as an extra washer. This will give your bolt plenty of headroom.


Insulate the thermal core.

Slide the shorter strip around the thermal tube and under the wires on the sides with no resistors.

Slide the longer strip around the thermal tube and under the wires on the sides with resistors.

wrap it up with some tape.

Pierce the insulation with a razor blade to reveal all four bolt holes.


Clear the bolt holes of any insulation. Insert four bolts in the bolts holes to make sure they can all screw in.


Place M3x22 into metal retainer plate.

Take the steel plate as shown and insert four M3x22mm bolts as shown. This will be the part that gets bolted to both the filament drive system and the thermal core.

Thread nuts onto bolts.

Thread four nuts onto the M3 bolts as shown. These nuts will keep the retainer plate firmly attached to the M3 bolts when they get tightened down in a later step. Put them pretty close to the top of the retainer plate.

Bolt retainer plate to thermal core.

Take the retainer plate and bolt the nuts into it using the provided hex wrench. Go ahead and tighten them down securely.

Tighten nuts against retainer plate.

Securely attach the retainer plate by tightening the nuts against it. This will lock it in place and become the mounting point.

Attach heat sink.

Provided in the kit is a circular heat sink. It is slightly oversized for the thermal barrier tube, so get your pliers and gently compress it a bit to reduce the diameter. Once you do that, it should have a nice friction fit over the thermal barrier tube. The heat sink is not strictly necessary, but it does help with keeping excess heat in the hot end and not the filament drive.

Attach the hot end to acrylic assembly.

Attach the hot end to the filament drive system. The four bolts sticking down should fit into the corresponding holes on the metal retainer plate. The top of the thermal barrier tube should also fit into the hole in the bottom of the filament drive mechanism; sand or use a file to enlarge it if necessary. Pop it into place as shown.

Put some nuts on the end of the retaining bolts and tighten them down with the pliers.

Route wires through appropriate slots.

On either side of the supports are some conveniently placed gaps that are perfect for routing wires though. We prefer to route the heater wires through one slot and the thermocouple/thermistor wires out the other slot. This will keep things tidy and also help you remember what is what.

Tape on thermal cape under the motor

The thermal core can generate quite a bit of heat, so we've provided a thermal cape made from PET that should be taped on the back of the extruder as shown. This will prevent the vast majority of the heat from moving up and potentially overheating the motor.

NOTE: This part may be a silver color or clear; both work.

Completed Plastruder MK5, Wrapped Correctly


Next Step: Body Assembly.

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