MakerBot Stepstruder MK7
If these instructions don’t seem to match what you received in your kit, see the Stepstruder MK6+ instead!
The MakerBot Stepstruder MK7 is our first dedicated 1.75 mm filament extruder. This extruder was designed from scratch, and contains a number of custom manufactured parts. We’ve learned a lot over our past extruder designs, and incorporated a lot of those lessons here: that’s why it’s smaller, lighter, and faster to build. And since it’s designed from the ground up for 1.75 mm filament, it’s light-years ahead of past designs in small-filament reliability.
1. Gather your tools
Provided: 1.3, 1.5 and 2 mm hex wrenches. Not Provided: Small flat head screw driver, pliers.
2. Gather your parts!
The main assemblies here are these four:
- Hot End: Nozzle, Heater Block, Barrel, Bar Mount, Bolt, Heater Core, Thermocouple(found in Gen4 electronics kit), Ceramic Tape, Kapton Tape
- Cooling block: Fan, Heatsink, Themostat, 5/8″ Spacers, Long Bolts
- Drive system: Stepper Motor, Knurled Pulley, Setscrew, Molded Drive Block, Delrin Plunger, Rubber and Metal Washers
- Extruder mount: Mounting Panel, Spacers, Thumb Screws*
*You put these together in the prep stage
3. Assemble thumb screws
If you haven’t done this previously, you’ll need to assemble the thumb screws.
You need two M5x20 bolts and two M5 thumb screw caps.
Using pliers squeeze each bolt into a cap. Be careful not to damage the threads.
Squeeze the bolt head into the cap to ensure a secure fit.
Tip: Two pliers can be used at the same time. We recommend you use pliers with long handles, for best leverage.
You should have two M5x20 thumb screws.
4. Attach drive gear to motor
You need your
- stepper motor
- drive gear
- M3 set screw
- and smallest (1.3mm) hex wrench
1. Disconnect the existing motor cable.
2. Place the drive gear over the motor shaft. Place a piece of paper between the drive gear and motor to create a small gap.
3. Tighten the set screw against the flat of the motor shaft. If the set screw doesn’t fit well against the flat section of the shaft, turn the pulley around 180 degrees and set the screw firmly — this should provide more than enough grip.
4. Then you can attach the longer cable we’ve supplied, and your motor should be ready to go.
5. Assemble the drive head.
You need:
- the stepper motor assembly
- drive block front
- drive block back
- Delrin plunger
- two M3x18 flat head bolt
- two plastic washers
- three metal washers
- 1.5 mm hex key
1. Place the plastic and metal washers on the Delrin plunger as shown.
2. Place the drive block back on the motor with the cable facing away from you as shown.
3. Place the plunger assembly in space on the right for single configuration. This is also the configuration for the left-hand side extruder in dual extruder configuration.
4. Place the drive block front on the assembly.
5. Place 2 M3x18 bolts in the holes and tighten.
6. Ensure that your assembly appears as shown below:
7. Ensure that the alignment between the filament channel and the MK7 drive gear is good.
6. Assemble the bar mount and thermal barrier
You need:
- the bar mount
- thermal barrier tube
- one M6 nut
- the supplied wrench
1. Orient the bar mount such that the chamfered edges face you and the horizontal holes are close to the top. If you don’t do this, the bar mount will not fit into the rest of the assembly. Thread the thermal barrier tube into the bar mount.
2. Loosely thread the M6 nut onto the thermal barrier.
3. Turn the thermal barrier until it is flush with the M6 nut. Finger tighten.
4. Grip the M6 nut with the wrench and tighten against the bar mount.
5. Check that your assembly looks like this.
The lip of the barrel should be just barely poking up, but no threads should be showing.
6. As a safety check, look down the barrel, preferably towards a bright surface. You should not see any metal burrs inside the barrel. If you do, push a short length of filament all the way through, and then discard the used filament. Metal burrs left inside will cause severe jamming, and require you to take the entire hot-end apart.
7. Assemble the thermal core and nozzle
You need:
- the nozzle
- thermal core
- 2.5 mm hex key
1. Place the hex key through the thermal core. This will give you a good grip. Then, thread the nozzle into the side with the small M3 hole.
2. Grip the nozzle with an adjustable wrench or pliers. Tighten the nozzle against the thermal core.
3. Once the nozzle is snugly in place, continue.
8. Assemble the mount plate and bar mount assembly
You will need:
- the mount plate
- M6x10 bolt
- M6 nut
- bar mount assembly
- the 10mm wrench
1. Thread the M6 bolt onto the thermal barrier, but don’t tighten it down yet.
2. Thread the M6 nut into the bar mount. Leave a several millimeter gap.
3. Place the mount place in front of you with the double notch on your left. Place the bar on top of the mount plate such that the thermal barrier is in the center. Ensure that your parts appear as shown.
4. Slip the mount plate into the gap between the bolt head and bar mount. The chamfered edges should face forwards. Ensure that your assembly appears as shown.
5. Use the wrench to tighten the M6 nut and bolt. You want the bolt and thermal barrier to be touching the back of their slot in the mount plate.
9. Mount the heater and temperature sensor
You need:
- the extruder assembly
- cartridge heater
- thermocouple
- M3x5 bolt
- M3 set screw
- M3 washer
- 2.5 mm hex key
1. Insert the set screws for these components. Thread a socket head M3 and washer.
2. Next install the smaller set screw for the heater cartridge. Just turn it a few times, you do not want to obstruct the cartridge for insertion.
3. Place the cartridge heater in the thermal core with the wires toward the rear of the extruder. An equal length of the heater should protrude from either end.
4. If you received a recent MK7, you might have received a heater cartridge that looks like the one below. If so, simply insert the cartridge as fully as possible into the block. There will be enough metal contact to ensure good heat transfer.
5. Secure with the M3 set screw. Tighten only until you cannot push it out from the metal end by hand. Any tighter and you run the risk of stripping the threads.
6. Secure the thermocouple against the thermal core with the M3x5 bolt and M3 washer as shown. (Again, the thermocouple is found within a bag in the Generation 4 electronics kit if your Stepstruder MK7 came with a Thing-O-Matic kit.)
It is advisable to put a single layer of kapton tape over the head of the thermocouple to electrically insulate it from the extruder. This is required for all Dual-Extruder configurations, as two uninsulated thermocouples will interfere with each other.
Cover both sides of the thermocouple in Kapton tape.
Now, bend the tip of the thermocouple 90 degrees.
Place the thermocouple under the set screw washer and tighten it down.
Tip: It is easier to tighten in place if the hook points clockwise.
Once the thermocouple is securely bolted you’re ready for the next step.
10. Insulate the Heater
1. From a length of ceramic tape, measure and cut a 3-inch segment. Then, cover the ceramic tape with a layer of Kapton tape. You can use any width of kapton tape for the covering. This makes the insulation easier to work with and also helps thermally insulate the head.
2. Starting at one end, cut a 1cm long 5mm wide slot toward the center of the segment, skip along 1cm, and cut another 1cm slot. The center slot allows the nozzle and cartridge heater set screw to be accessed.
3. Place the insulation on the heater, so that the nozzle pokes up through the center slot. The “legs” of the insulation should be facing away from the cartridge heater.
4. Wrap the uncut insulation around the bottom, tape it down to the heater core, and tape the legs back to the body when they pass the barrel.
5. Next, add an extra 1/4″ piece of ceramic insulating tape to the side where you’ll mount the thermostat. Cut a 1/4″ piece of ceramic tape and install it like this, on the thermocouple side of the block:
6. Now tape thermostat to side of heater core that does NOT have the heater in it; you want it on the nozzle side so it doesn’t trip at normal operating temperatures.
11. Secure the thermal core assembly
You need:
- the mount plate assembly
- the thermal core assembly
1. Thread the thermal core onto the thermal barrier.
2. Tighten the heater core down as tightly as you can with your fingers. The core might not line up perfectly with the slots as the illustration shows, but a solid connection is more important than the orientation.
3. Ensure that your assembly appears similar to what is shown. And again, your thermal core may not be in the same orientation as pictured.
12. Putting it all together
1. Place 2 M3x45 bolts in the fan as shown.
2. Place the spacers on the bolts. Note the orientation of the wires and label.
3. Place the fan assembly onto the heatsink.
4. Take the fan assembly and put the bolts through the mount bar and into the motor as shown.
5. Tighten the bolts down.
13. Connect the fan extension cable
1. Solder 24 inches of black/red cable to the fan leads as shown, and insulate with heat-shrink tubing or kapton tape. If your fan has a plug or terminal at the end of its wires, you’ll need to clip it off before completing this step.
Congrats! Your MK7 is built.
Go on to build your safety cutoff, build your Thing-O-Matic’s body, and complete the electronics setup.
24 Comments so far
Robbie
The three metal washers under the Assemble Drive head were not in my kit. How can I get them?
Robbie
There need to be some clarification to the as to which end of the wires to tape in the step:- “Secure the thermocouple against the thermal core with the M3x5 bolt and M3 washer as shown. It is advisable to put a single layer of kapton tape over the head, to electrically insulate it from the extruder. This is required for all Dual-Extruder configurations, as two uninsulated thermocouples will interfere with each other.
Cover both sides of the thermocouple in Kapton tape.”
I got it wrong and want to see clarity in this step.
Robbie
A more accuate way to make the holes in the ceramic tape is to tape one end down just shy of the rear of the nozzel opening, bend the tape around to the nozzle and then cut the holes for the nozzel and the set screw. I used Squizzers (Item Item #81204 from Micromart.com)
Robbie
In the step “Connect the extruder thermostat to the “sensor” port of the safety cutoff board as shown.” don’t confuse termostat for thermistor.
Robbie
Calibration links not working.
If you haven’t already, set the potentiometer values on your stepper driver board as shown here. Keep in mind that the MK7 ships with a Moons Stepper, and the REF voltage should be between 1.675 and 1.680 volts.
You’ll also need to recalibrate the Thing-O-Matic height as decribed here. This video has step-by-step instructions on the process as well:
Scott Leslie
I would also like clarification about which wire gets attached under the M3 nut on the extruded.
Also, the pics of the power port orientation on the stepper motor are inconsistent.
Lloyd
There is no clear instructions for those upgrading from the MK5 direct to MK7.
Specifically:
* Stepper driver card installation, connections and reminders on how to use the Y-cable power splitter.
* The extruder motor power cable is not long enough, so the cable has to be routed on the front-left side. Then plugged-in just before closing the chassis.
I had to look for the information all over the site and figure it out myself.
RTFM of course but It’ll be nice if documentation was also organized for the average person…(ie. no links branching out all over).
steve cooley
I thought my thermocouple wire was missing. It’s not. It’s in a wax paper envelope in another box. The instructions minimally state that it’s in the “mk4 electronics” box, and that’s true. It’s the box with all the steppers, rods, and PCBs. Then it’s in a clear plastic baggie along with the SD memory card.
Zomg, that was frustrating.
steve cooley
And when the time comes to actually install the mk7 onto the z-axis, you can find the instructions on this page.
http://www.makerbot.com/docs/stepstruder-mk7-assembly/
This assembly step would be nice to have on this page.
Matthew Kelly
Two comments I would make would be that the pictures here are confusing. As you follow the build the orientation of the drive block in relation to the stepper motor changes. Which is correct? Also, it would be a huge help to everyone to know that the thermocouple Type K is located in the Generation 4 Electronics Kit. Its a small part and hard to find even if you knew where to look. So to anyone wondering where the thermocouple is. Look in the Electronics kit. It is in a small waxed envelope.
Ben Harris
“Then it’s in a clear plastic baggie along with the SD memory card”
THANK YOU!!!
Lou Flemal
Does anyone see an a disadvantage to adding a small strip of fiberglass tape to the end of the heater core that has no wires? Seems like it every little bit of insulation would help, no?
Eamon Egan
In my kit, the flat part of the drive motor shaft does NOT go far enough down to engage the set screw when the drive gear is low enough to align with the filament channel. I hope this is OK – normally I’d prefer to tighten the set screw against the flat channel.
Also, I noticed I got a second drive-gear-sized set screw (Loose in one of the small bags – easy to miss! The first one was already in the drive gear). Is this just spare, or is it to be used for locking the first set-screw?
Eamon Egan
I just figured out the small set screw is for the heater cartridge…
AndrewO
If you’re having trouble finding the set screw for the drive head, it might already be in the hole. I was trying to use the other set screw (for the heater cartridge) on top of that one, which would make it impossible for the motor to spin inside of the drive blocks (and also mean that I’d be one set screw short).
Andrew Lindsey
Two comments so far on my build:
1. The flat on the stepper motor shaft does not go down far enough for the drive pully to be in the right position. I had to turn the shaft around and tighten the set screw down on the smooth part of the shaft.
2. My cartridge heater has a welded-on strain relief assembly for the wires which makes it impossible to insert it all the way into the thermal core.
Eric
is there a way to adjust the Delrin plunger? I had to take apart the assembly in order to feed the plastic through. I also had to remove one of the three washers for it to fit. I’m using 1.75mm ABS.
Arnaud
I also had to remove 2 metal washers for the plunger to let the plastic pass through (still snug fit of course). With only 1 washer out it was still too difficult to pass through to my taste… Hope we’re not wrong on this
Ethan
Thanks for the comments — I’ve update the instructions to more clearly indicate the location of the thermocouple as well as the motor pulley issue and the cartridge with strain relief; hopefully this will help future builders.
@Eric — it’s easier to load the filament initially with just two washers, but you’ll likely have to add that third washer back in after the plunger wears a bit. I’ll pass along your question about adjustment to the R&D team.
Patch Eudor
In the pictures for this build the orientation of the drive block changes in reference to the stepper motor. The wire harness moves from exiting the side to exiting the top. In my particular case I assumed based on the wire runs that having the harness exit from the top would be best to keep the wires out of the way. Heck, that’s what many of the pictures showed.
Well. It turns out that the moons stepper motor I received isn’t actually square, it’s slightly rectangular. With the wire harness positioned so that it was at the top I couldn’t get the filament to feed with the three washers on the plunger and when I went to two it slipped. I adjusted the drive gear to no avail. I tried every combination I could think of and nothing. For hours I hit my head against my desk till I remembered: “hey – in the instructions wasn’t their something about the wire harness exiting to the side?”
Anyway, I moved the stepper motor so the harness exits my left (while looking at the front) as shown at the beginning of the instructions, put all the washers on the plunger and crossed my fingers. It has been loading and feeding filament like a dream since. No more drama. So to answer Matthew Kelly’s question about the orientation above and some of the questions about the washers. In my particular case it ABSOLUTELY mattered. I went from wanting to toss my MakerBot into the trash to printing everything under the sun. Okay, it only arrived six days ago so I’ve not printed everything, but someday.
Mac
I just wanted to mention that the heat sink fan plug has to be removed in order to solder the additional 24″ of black/red wire.
Ethan
@Mac — good point! Edited that step.
Dana Zimmerli
A couple of suggwetions and a couple of BIG questions: First, I did finally find the thermocouple (from now on I will abbrviate to tc) after reading all the comments. It is in the wax (? not really wax is it?) envelope, and looks like the one in the initial parts picture for the “Hot End” Also in this picture, (incorrectly, maybe) is the Thermostat — which I initially thought was the tc. One other problem with this picture is that the heatre core is shown without wires? So, the next picture lists the thermostat, but does not show it. The next time we seed the tc, it is in the step Assemble the thermal core and nozzle where it is not used. These photos are confusing.
On to my questions concerning the tc. In the photo with the Assemble the thermal core and nozzle step the tc looks just like mine. the next time I see the tc, it looks quite different — the long wires are no longer there, the tc is not black plastic, and the tc is covered in Kapton tape. What step changed the tc that much? My ole Complex Aldebra professort would have called this “Obviously.” But the instructions when writing technoical documents at my first job said “Never use the word ‘Obviously”‘ unless you follow it with ‘You satupid idiot’ because it is either obvious so you don’t have to say it or it is an insult.” So I need to know what the “obvious” step is. And following that, after bending something 90 degrees, (what precisely) you want to placed the “hook” under the screw. I don’t see any hook. Is this also so obvious?
So I think some clearing up is necessary, at least for me.
Rebecca
The final assembly shows the stepper motor cables to be back of the assembly, but in the beginning of the instructions for installing the drive block, it shows them to the side. I am not sure it matters, but can you tell me if it does before I get too much further?