Stepstruder MK6 Electronics Assembly

Testing Your Extruder

Now that you have your extruder wired up, you'll want to test a few things. This will help you diagnose problems before they actually become problems.

Test 1: (MK6 Original only, not MK6+) Measure heater resistance.


With the new heating system, everyone should have nearly identical heaters and heater profiles. The supplied power resistors are high precision (1%) 5 ohm resistors. Since they are wired in parallel, the resistance should be 2.5 ohms. Measure it with a multimeter. If it is any other value, make sure you wired them up correctly and that there are no shorts.

Test 2: (Gen3 Only) Measure thermistor resistance.


With the Gen3 electronics, you'll be using a thermistor to measure temperature. At room temperature the resistance should be around 90k. (As the ambient temperature increases, resistance will go down.) If it is not in that vicinity, check that you have it wired up properly and that the leads are not shorted.
Gen4 users can just skip this step.

Stepper Motor Driver

Set Stepping Modes

Ensure both switches on the stepper driver are set to "ON" as shown. This puts the drivers into "microstepping" mode, which makes your Thing-O-Matic perform smoothly.


Adjust Stepper Driver Potentiometer settings


The potentiometers on the Gen4 Stepper Drivers are important to set to the suggested values to ensure that you are controlling the extruder correctly. For more information, please see the Thing-O-Matic calibration page

Stepper Motor PFD (V) RC1 (V) REF (V) RC2 (V)
Stepstruder MK6 2.31 0.94 1.56 0.94

It should look like this (The dimples on the resistor have been painted black to make them easier to see)


Assembling Stepper Driver IDC Connectors

Separate the Wires

The stepper drivers are connected to the motherboard via a 6-pin IDC cable. You must make these cables yourself, which is a fairly simple task. Once that is complete, you just plug and play.

The stepper motor drivers ship with a 10-wire IDC cable in order to be compatible with the Generation 3 Electronics. You're going to be using all Gen4 stuff, so let's turn the 10-wire IDC cable into a 6-wire IDC cable.

All you really need to do is remove 4 wires from the cable.


Attach IDC Connectors

IDC connectors are an awesome connection technique for making mass connections. The idea is pretty simple: the connector has metal "teeth" that "bite" through the wire insulation and make an electrical connection when the connector is clamped onto the cable. If you look into the IDC connector, you can see the individual teeth in two offset rows.


Making the connectors is pretty simple, if you follow these rules:

  1. The cable color order must match on both ends of the IDC connector.
  2. Have someone double check your work before you clamp it down.
  3. Only apply force straight down into the top of the IDC connector.

To actually make the cables, take one cable and two IDC connectors (one for each end). Insert the cable into the gap in the IDC connector, and make sure everything is lined up nicely. Make sure the color order (when viewed from the same side) is identical for every single connector you make.


Once you have it right, gently press down on the connector with your fingers. This will make the connector grip the cable and keep it from slipping out when you go to clamp it.


Vise Based Clamping

Clamping the connector is easiest when you use a benchtop vise. If you have a vise, put your connector into it and then clamp it until the connector is closed like the pictures above. Do not clamp it any farther as you will crush the connector.


Alternative Clamping

Making these connectors has been achieved with pliers, C-clamps, or even a piece of wood. We don't recommend doing it this way, but if you absolutely have to improvise, then make sure that you are applying even pressure straight down into the connector from the top. Any other direction and you risk breaking the connector.


Mounting Stepstruder MK6 Stepper Driver to Base Plate of Thing-O-Matic

Insert 4 M3x16 bolts into mounting holes in the Gen4 Stepper Driver


Place the 1/4" M3 spacers on the 4 bolt like the image below


Mount the stepper driver on the front side of the base plate in the Axis A location.


Use the Molex Y-Splitter to connect power to the board

WARNING: Make sure you have read and understand the correct way to use the Molex Y-Splitters as seen in this blog post:

Insert one end of the IDC connector to the stepper board as shown


Insert the other end of the IDC connector to the mother board as shown


Insert motor connector into stepper driver

With the completed Stepstruder mounted to the z-stage, route the cable coming from the motor through the front left port and connect it in the orientation shown. (The exposed metal should match the connector of its neighbor)

Connect Fan Leads into Extruder Controller

Insert the wires coming from the fan through the back right wire routing holes and into ports 1A and 1B in the extruder controller

Connect Thermocouple to Extruder Controller

Inser the wires coming from the thermocouple through the back right wire routing holes and into T+ and T- in the extruder controller.

Connect Extruder Heater to Extruder Controller

Connect the extruder heater wires to the extruder controller. The extruder heater does not have polarity. Note: If you are using the Safety Cutoff Kit, polarity DOES matter.

Please note: If you have a MK6 Plus Stepstruder, you need to use the Safety Cutoff Kit. The cartridge gets too hot to use without one.


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