Prusa Core One(+) Accelerometer Installation Details  

Prusa Core One(+) Accelerometer Installation Details

This post is intended to assist other users who need to attach the accelerometer and perform Input Shaper calibration and Stepper Motor Phase calibration for the first time.

If you have never done this before, you likely landed on this help article for attaching the accelerometer:
https://help.prusa3d.com/article/accelerometer-core-one-mk4-s-mk3-9-s_729349

The above article is sorely lacking in detail, especially with regard to what steps to follow when attaching the accelerometer to the print head,
and what will happen after that when you select the calibration of Input Shaper or Phase Stepper.

Here is some of that missing detail.   I hope that Prusa will edit the help article and provide the missing steps.  START WITH THE PRINTER TURNED OFF!

1.  Install the SHORT accelerometer jumper cable between the socket on the main control board that is shown in the help article instructions circled in orange, and the hidden connector inside the WiFi module after you remove the WiFi plastic cover.    Then reinstall the WiFi module and cover, and reinstall the main control board sheet metal cover.
2. Do NOT connect the accelerometer yet.   Turn ON the printer. 
3. Perform Belt Tension check and adjustment if needed.  You do not want to perform Input Shaper and Phase Stepper calibrations until you know the belts are properly tuned.  So check them now.
4. We are now ready to move on to installing the accelerometer.   First: If the build plate and bed are not near the bottom,  go into CONTROL -> MOVE AXIS -> Z-Axis, and move the build plate bed DOWN between 175mm and 200mm, so it is far away from the print head.
5. Turn the printer back OFF!
6. Behind the rear Z-Axis worm-screw rod, there is a hole in the back panel covered by a black rubber plug.   Remove this plug and set it aside.
7. Route the LONG cable for the accelerometer from the inside of the build chamber, through that back panel hole, and connect it to the visible
   white socket on the WiFi module.   Connect the other end of that long cable to the accelerometer, and assemble the two plastic parts as shown on the help article that is linked above.
8. Remove the silicone sock from the print head heater block, being careful not to damage the small wiring above it.  Set it aside.
9. Gently push the open end of the accelerometer assembly onto the nozzle and heater block assembly.  The accelerometer 3D print is intentionally stiff for this rectangular opening, and may require some gentle but firm force.   Be very careful about twisting off axis, to avoid bending your heat block or heat break.   If you have the right tool or finger nails, you may be able to gently spread the two long sides of the accelerometer plastic to get it started sliding onto the print head heater block.   Push it up until it is firmly seated.
   NOTE:   The accelerometer cable will indeed try to rest directly against the Z-Axis vertical worm-screw rod, and when you later start the calibration, the Z-Axis may move (home), but this will not damage the cable.  It may get a small amount of grease on the cable that can be wiped clean when all done.
10. Turn the printer back ON.
11. Use the SETTINGS menu on the LCD panel to select INPUT SHAPER and then Calibration.   Follow the on screen instructions.   NOTE:  Do not panic, but the process will HOME the system and bring the build plate into contact with the bottom of the accelerometer.   This is why the accelerometer bottom is flat and plastic.  Nothing will be damaged.  When the calibration is completed, the values are automatically stored.  There is nothing else you need to do.
12. Use the SETTINGS menu on the LCD panel to select PHASE STEPPING -> Calibration.      Follow the on screen instructions, and the values will be saved automatically when the process completes.
13. When done, exit the settings menu.
14. Ensure that the build plate and bed are moved down and away from the print head,  and Turn OFF the printer.
15. Carefully and gently remove the accelerometer from the Print Head assembly.  It may take some downward force.   If you can fit a finger nail around the top edge of the accelerometer black plastic (without harming the heat block small wiring), and spread the plastic outward it may help to start sliding the accelerometer loose, downward, and off the print head.
16. Put the accelerometer, with it's long  cable still attached, in a storage bag or box.
17. Re-install the silicone sock on the print head heat block.
18. Re-install the small rubber hole plug onto the back panel behind the rear vertical Z-Axis worm-screw rod.

I hope these instructions can help other new users until Prusa can re-write that above linked help article.
As you can see, there were a fair number of questions and concerns for a first time user that were not provided
in the article.   But the Technical Support Chat option was very good, and the support team is great, so I was able
to figure it all out with very little delay.

Cheers,

Neal