Hello! This repo should (hopefully) help you put an Hemera onto an Ender 3 Pro in the year 2021 in a breeze. I mostly created this because I was following Hemera to Ender 3 - Complete guide but some information was outdated; hopefully this will help one or two people in the future.
This is not meant to be a complete guide but a diff to the video above so you should go watch it first and then come back here.
As a headsup, you can definitely do the installation in three steps: first the Hemera, second adding the part-cooling fan (I still had great success without a part cooling fan at first), third the BLTouch.
Contrary to the video, I feel like the two part build is pretty heavy and make you loose a lot of space for no reason.
I actually used the part from E3D hemera Mount and cooler for Cr-10 and Ender 3 by Tragical which are much better and do not make you loose any build volume.
You'll find bellow (quick links to the stl folder) some remixed versions.
HemeraMount.stlSTL ( remix to make the BLTouch mount nut slots a bit bigger so it's easy to use even with shrinking (at the end of the day, you don't need something snug))PartFan.stlSTL +PartFanArm.stlSTLBLTouchMount.stlSTL (completely changed from original to not bumps into the Y axis motor without triggering the end switch) You need to add a support enforcer when printing as show here
Fan mount:
- 2x M4 hex nuts
- 2x M4x22mm screws (if you want to be safe and not do back&forth to the store, also get some M4x20mm & M4x25mm, you can always reuse in the future)
BLTouch mount:
- 4x M3 hex nuts
- 4x M3x10mm
Once mounted it should look like this!
I couldn't find easily the documentation online about what is Vref, Irms (sometimes just called RMS) so I'm doing a full section on it so it's clear for you. Vref calibration is actually pretty simple and you don't have to be very precise! It basically just set the upper limit on what current you can send to your stepper motor without blowing it.
What you need first:
- Know the motor drivers you have on your board (for me with a Creality Silent Board 1.1.5, that was TMC2208)
- Know the "Rsense" value installed on your board. You can look this up online or directly on your board (the resistance close to where you plug the E stepper motor should have a number on it). Most of the time, it should be "100" which is a 0.100 Ohm resistance. For me on the Creality Silent Board 1.1.5, Rsense=150
You then can refer to the Hemera documentation (alternate link if down)
For me with TMC2208, it will tell you to use Irms (which is basically max current divided by square root of 2 with some formula) What's really not clear here is the computation is actually just a cross product which tells you at 2.5V, your driver will deliver x amp. Refer to the driver's documentation to try to find that value. For TMC2208, the documentation is here. Page 49, you can see with Rsense=100, Vref=2.5V => Irms = 1.77A. With Rsense=150, Vref=2.5V => Irms = 1.28A.
The Hemera should be driven with a max Irms= 1.33A*sqtr(2) = 0.94A. With Rsense=150, I want 0.94A and for Vref=2.5V,Irms=1.28A. With a cross product, that gives me Vref = Irms_want / Irms_at_2.5 * 2.5V = 1.83V. That's the maximum value you can ever set your Vref at before you burn your stepper motor. It is recommended to set a value at ~80-90% of that maximum value to be safe. I initially set it to the value in the video (0.5V) and that definitely didn't work so I would recommend not setting it to < 70% max value. As you can see, Vref doesn't actually need to be accurate, you can set it anywhere between 70% & 90% of you max value. In my case (Creality Silent Board 1.1.5), I want to set it between 1.28V & 1.65V.
Remember that:
- If you set your Vref too high, you can break your stepper motor so always do the computation and that will give you the upper bound
- If you set your Vref too low, your motor won't move or "skip steps" (so basically not extrude correctly). Since I never had a stepper motor overhead, I set mine at 90% of max and it has been doing fine.
tl; dr; Don't change Vref except if you run into issues. The stock value works except if the new stepper is 2x more powerful than previously. The Hemera stepper motor should be more powerful than the stock one so no risk of damaging it.
I don't remember too much this step so I won't go too much into details. If you have an arduino, there should be plenty of guides. If you use the Creality BLTouch kit, you can follow this reddit thread.
Two things worth mentioning:
- The
DC, D6, FD and FFvalues are correct (opposite of what's in the BLTouch kit guide), this is because you are flashing the bootloader and not the firmware. - There is one step not mentioned in the guide: you need to select the correct microprocessor that is on your board
After you have succesfully flashed the bootloader, you'll be able to repeatedly flash the firmware with an attached Octoprint (or similar)
- Download the latest firmware from https://github.com/MarlinFirmware/Marlin/releases
- Download the correct config from https://github.com/MarlinFirmware/Configurations and override the
Configuration.handConfiguration_adv.hwith files for your printer - You can modify the values as shown in this commit: https://github.com/Viq111/HemeraEnder3/commit/fd97170 (make sure to set the correct driver for the board you are using, you can also look at the other commits)
- Use VS Code & PlatformIO to build (don't use Arduino IDE, that has been deprecated and is hard to get it working now)
Now you should have a working Ender 3 with a Hemera hotend!
A fully working copy of Marlin is also available in the Marlin folder of this repository
If you used the M206 to set your home previously, with the BLTouch you will need to actually (physically) modify your end stops as M206 doesn't work for the BLTouch. Once you have set them, don't forget to reset your M206 to zero.
On the software side, you will want to pick this additional configuration.