We are using Sherpa mini extruder developed by Annex Engineering which is one of the lightest extruder to this date available on market weighing at 140gms only. We printed our Sherpa mini in ABS Filament and used parts from cloned Aliexpress BMG extruder which was laying around in our shop. We found a simple yet affective mount on Thingiverse by “theFPVgeek” which enabled us to use stock hot end and fan mount. Sherpa mini uses Nema 14 stepper motor.
This extruder is the reason we were able to print at speeds of 100mm/s with stock board. And with 32 bit board we believe we can go faster than 100mm/s. This extruder has so much torque. The only changes we had to make to the firmware was Extruder E-steps configuration. This was the hardest part of this entire build. For those who want to use Sherpa mini Extruder with marlin the Esteps for this extruder is around 721 steps (@16 micro stepping) at least it was in our case. Stock Ender 3 extruder has 93 Esteps.
At these speeds we need better cooling. So we found a part cooling fan upgrade on Thingiverse by “tunnelcake”. It uses 5015 blower style fan. This LDO Nema 14 needs lot less current so we dialed down the voltage to 0.280 v. Guys this part is very important because stock motor current is set to around 1 amp and it only needs 250 to 300 milli amps. We can easily burn this motor if we do not adjust current.
Stock Ender 3 board uses Pololu A4988 stepper drivers. There is lot of information available on internet for calculating current for A4988 stepper drivers. After all these changes the motor is still getting hot than normal. So this is something to watch out for when printing at high speeds. LDO motors are good for up to 180 degree Celsius but than there is risk of melting printed parts. That’s why we used ABS. PLA 3d printer filament is not recommended. Annex Engineering recommends ASA.
We are using mainsail OS for this particular build. Stock Ender 3 screen is compatible with klipper which is a plus unlike reprap firmware where we need special touch screen which is expensive. We can control printer via web interface which makes life much easier and no need to use SD card. All we have to do is to save G-code file on computer and upload it to Klipper via web interface over Wifi. Raspberry pi Zero W has built in Wifi module in it. When we install mainsail we have to manually configure wifi by entering username and password. We can access web interface via an IP address.
Klipper is originally designed for Octoprint and we all know how good Octoprint is. Because we are using low power Pi Zero, Octoprint does not work well with Pi Zero. For Octoprint to work properly we need at least raspberry pi 3b which is really hard to find these days and Pi 4 is expensive. Mainsail OS is very light and works best with Pi Zero.
So far we have encountered no issues using pi zero.
Just like reprap firmware we can make changes to config file in web interface without turning printer off. Simply click save and reboot button after making necessary changes and you are good to go. Where as in marlin you have to turn resin 3d printing off make changes in IDE than compile firmware and then upload it via USB or serial connection.
If you like this content do leave a comment below let us know what you think about this upgrade. If you are interested in this mod contact us @Facebook/BuraqStudios
NOTE: Stock Ender 3 board does not come with bootloader installed on it from factory. So first we have to install bootloader in order for this upgrade to work. There are lot of tutorials available on internet on how to install bootloader on ender 3 using Arduino UNO.
Useful resources:
Klipper OS: https://www.klipper3d.org/Installation.html
Example Configuration Files: https://github.com/KevinOConnor/klipper/tree/master/config
Octoprint: https://octoprint.org/
Mainsail OS: https://github.com/raymondh2/MainsailOS/releases
Sherpa Mini Extruder: https://github.com/Annex-Engineering/Sherpa_Mini-Extruder
Ender 3 Sherpa mini mount: https://www.thingiverse.com/thing:4687721
Stock Adapter 5015 blower fan Duct: https://www.thingiverse.com/thing:3433290
