Long story I'll try to bullet point to speed up so bear with me:

  • I have a heavily modded Ender 3 Pro
  • Relevant mods for this question: Control board swapped for BTT E3 RRF, Dual Z motor, BLTouch
  • Ultimately I'd love to convert the Ender 3 pro to have IDEX, probably after I make it bigger with an Ender extender kit, but it's cool if it takes a long time
  • Whether or not its easier to just build a large printer with IDEX (rather than continually changing my Ender 3) is a different question, but I just like modifying my printer. I like learning along the way
  • Right when I got my BTT E3 RRF and my dual Z motor, I thought it'd be awesome to be able to do G34 auto alignment, much like Teaching Tech describes in this video. The BTT E3 RRF has a port for a second Z-axis motor so I thought I was good
  • Come to find out that (I believe) the second port on the board is actually just driven off the same driver, I don't believe it can be controlled separately (correct me if I'm wrong).
  • Somewhere on the internet I read that if you get the IDEX expansion board from BTT it can do that, so before I researched further, I bought one.
  • And as you can see in this video from Aurora Tech, you can do indeed do G34 with the IDEX board.
  • The problem is, it looks like in that video she actually plugs the Z motor into the slot meant for the extruder motor.

Which brings me to my question:

I want both. I want to be able to do G34 but also eventually run a fully functioning IDEX. I've already bought both the BTT E3 RRF and the IDEX board.... am I out of luck? Do you need an Octopus board or something? Or is there a way to do both with the hardware I have now?


1 Answer 1


The basic RRF board has a single Z driver which connects to two Z stepper sockets.

In order to individually drive two steppers, you need an optional stepper driver like in a dedicated Z2 stepper driver or a spare E1 driver to function as the second Z driver. The basic RRF board only has four drivers, so this board alone will not bring the functionality of individual driven Z steppers.

The extension board for support of IDEX gives access to another two stepper drivers, an X2 and a E1. Both are required for the second X-axis, so this expansion board will not give you a spare for the second Z driver.

With the boards you acquired you can therefore not have both dual individual driven Z screws and an additional X-axis with additional extruder (IDEX) using the current onboard drivers (including the breakout board). You need a board with at least 7 stepper drivers, but, if there are free pins available you could add an additional stepper manually in firmware.

  • $\begingroup$ Thank you, I'll have to look at it later to determine if there are free pins. Do you happen to have any resources (videos/articles etc) for how I would add a stepper if there are free pins? $\endgroup$ Oct 15, 2021 at 12:00
  • 2
    $\begingroup$ @JosephCrozier Excellent question, please post it! 🙂 On second thoughts, this might answer it. If not, post a question. $\endgroup$
    – 0scar
    Oct 15, 2021 at 20:20

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