BTT SKR V1.4 Turbo on a Zonestar P802QR2

thingiverse

After the ZRIB board on my P802QR2 sprayed its Magic Smoke all over my room, I decided to upgrade the printer to the Big Tree Tech SKR V1.4 Turbo board. After a pandemic induced 3 months wait for delivery, the board arrived. Sadly, the Z axis on the board was defective. After 3 emails with BTT support, they mailed me a replacement board. *Kudos BTT*! I ordered the TFT 24 control head and stretching my FreeCAD abilities beyond their limits I designed a plate that mounts the TFT onto the control mount on the printer. Any critiques of my **tft 24 mount.FCStd** file will be greatly appreciated, especially of you have a way of aligning holes other than setting distance constraints to 0! Whilst I was awaiting the parts from China I upgraded to a Prussa MK3S to continue printing the PPE items for my family. Once the Prusa kit arrived I realized that I replaced my Chitty-Chitty-Bang-Bang with a full fledged Federation Shuttlecraft. Needless to say, I printed the TFT24 mount plate with the M3KS. The **configuration.h** and **configuration_adv.h** are the only two files you need build the Marlin 2.0 firmware for the Zonestar. My favorite Marlin build tutorial is by Chris Riley in Chris's Basement on YouTube <a href="https://www.youtube.com/watch?v=oHMZ0ocTYvM"> Watch Chris's two part tutorial here</a>. So if you're full tech or just tech adventurous have a go at it, it's not all that daunting. For those looking for a simple download the **firmware.bin** file may be copied to your SKR board's SD card. When you reset, the new firmware will be adopted by the SKR's boot loader. *Be aware!* You may have to adjust the reference current on the A4988 stepper motor drivers to tune the SKR to the Zonestar servos. I used some Zonestar red A4988's and some new ordered from Big Tree Tech. The second extruder would not move at all under load until I tweaked the Vref pot 15 degrees clockwise. I also had to tweak the first extruder and the Y axis drivers just a tad clockwise. <a href="https://e3d-online.dozuki.com/Guide/VREF+adjustment+A4988/92">A nice Vref tutorial may be found here</a>. If you have a multi-meter a Vref of 0.8V for the Axis Servos and a bit above 8 for the extruder servos worked for me. I could not get the extruder Vref's above 8.5 as per Zonestar's instructions. BTT says the TFT24 may be configured for the P802QR2 with the **config.ini** file provided. It sets the TFT24 to two hot ends and two extruders. Simply copy the file to the root of the SD card plugged into the TFT24 and reset the machine. I could not get the second extruder to appear.