Possible to get G34 auto align and IDEX with Ender 3 Pro and BTT E3 RRF?

Question

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?

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.