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Select-Switch - Directdrive or Bowden

A project log for CHANGER - a toolchanger new interpreted

CHANGER - a motion system which can be used for advanced 3D-Printing with up to four materials, PnP, PCB-Milling, Layer inspection, etc...

Simon WirzSimon Wirz 08/01/2021 at 10:320 Comments

Because of the limited stepper drivers of the Duet 2 Wifi + Duex5 I want to use the same stepper driver for the bowden stepper as well as for the directdrive stepper of each tool. This works fine because you have to decide and can't use both in the same tool. You insert either a directdrive tool or a bowden tool. Therefore you just have to switch between the steppers and change the config of the stepper driver (E-Steps, Direction and Current). 


1st Design (physical):

For the first design and prototype I've designed a housing for a 12pin DPDT-Switch (https://de.aliexpress.com/item/4001287918740.html?spm=a2g0o.productlist.0.0.29ca3addUpn6uJ&algo_pvid=b62583ef-d498-482f-b9ac-92b9e2239363&algo_exp_id=b62583ef-d498-482f-b9ac-92b9e2239363-8) in a ON-OFF-ON configuration so you're able to switch pin to pin and this for each stepper pole. To prevent the stepper driver from possible damage you just have to deactivate the stepper driver or just turn off the duet board before switching the drive (stepper). 

For wiring there isn't much space left but with some sure instinct it workes just fine. 

I've used three instead of two outputs to connect the direct drives either left or right for easier handling and cable management. the top is for the direct drive output. The bottom is the input from the duet driver. 

The final switch fully assembled and soldered...


Future Idea:

The physical switch is just for initial testing to proceed with the hole bulid of the CHANGER. In the end I'll design a pcb to handle the switching process. For safety reasons I'll detect the current in the coils to determine if the stepper is in use before switching between bowden and directdrive. The pcb sends automatically the stepper-off comand to the duet to deactivate the driver before switching to protect the driver. Just for the moment I'll proceed with the physical switch.

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