I custom designed and built a dual extrusion 3D printer and have been using it for about 6 months or so. It's my 2nd printer. My first is a Folgertech 2020 i3 kit that I've redesigned to 2 or 3 times over. It is now closer to a Prusa MK3 than the original kit it came from.

I like having the option for dual extrusion, and I do use it on 10% of my prints or so, but there are some drawbacks to the dual extrusion that I would like to resolve. My biggest complaint is the print quality hit I take from the unused print head dragging across the part I while I'm printing and leaving some ghosting or print artifacts behind. I also have to deal with the slight oozing that the other nozzle gives off when printing with dual print heads. I would like to make the hot ends independent of each other so I can leave the unused hot end parked off the side of the build area while it's not in use. I may even add some kind of an ooze shield by the park position so as it parks or moves back into the print area, the drippings from the nozzles get removed when the hot end passes by.

I've used a 2040 V-slot rail for my X gantry. It would be simple mechanically to add a 2nd drive belt (additional stepper motor and idler) to the rail and converting the printer over to have dual independent hot ends. I'm currently using a MKS Gen 1.4 control board with a 24V power supply, and I'm already using up all 5 stepper motor driver positions with the current printer configuration (X, Y, Z, E0, E1). To go with dual independent hot ends, I would need to add a 6th stepper driver to my controller in some way.

Does anyone have any recommendations on options or boards to add another stepper driver and control it for the independent hot end? I've seen stepper motor add-on boards and the like, but I'm not sure where to start. I am familiar with marlin firmware due to my history with it up to this point. I haven't ventured into marlin 2.0 on anything yet. I don't know if there is a standard way to add on a stepper motor to control the 2nd hot end x axis on my current board, or if I need to look for something like this (https://www.amazon.com/BIGTREETECH-high-Frequency-Printer-Control-12864lcd/dp/B07T2RLG2C/ref=cm_cr_arp_d_product_top?ie=UTF8) that has 6 stepper drivers support already built in.

Thanks for the help.

I'm doing an IDEX build myself and have an SKR V1.1 Pro on order. So I hope it would be sufficient for the purpose. Did you already order the board?

Another possibility is Duet Maestro with the 2 stepper daughter board, which gives you 7 TMC2224 stepper drivers in total. IDEX support is included in the standard precompiled firmware binary, so you won't even need to compile the firmware yourself.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Have you considered a nozzle lift mechanism like the ultimaker? Seems like a much simpler solution to me, and it also takes away the weight of an extra motor to drive the second X axis. You would be able to use standard firmware, with just a short "toolchange" gcode for when you want to print with a different color. You could even add more than 2 nozzles with this sort of design.