Project: Prusa i4 Single Z-axis motor Modification by ZahirSaleh

Last crawled date: 3 years, 1 month ago

Project: Prusa i4 Single Z-axis motor Modification
Why:
100% synchronization of the two z- axes screws
No loss in horizontal calibration of the z-axis even when one z-axis screw turned by hand accidentally.
Free one z-axis driver for expansions such as a second extruder.
Get a spare stepper motor may be?
Use the spare stepper (and freed driver) for extra extruder??? (will upload this soon)
Steps:
1) Download and Print all the stl files attached.
2) Remove the bearing from the original holding block by tapping it off gently with a blunt object. Link:https://www.aliexpress.com/item/Free-shipping-10pcs-lot-8mm-diameter-zinc-alloy-bearing-housing-KFL08-FL08-K08-flange-bearing-with/32363611626.html?spm=2114.01010208.3.2.UmD2Mk&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_10136_10137_10138_10060_10062_10141_10056_10055_10054_10059_10099_10103_10102_10096_10148_10052_10053_10050_10107_10142_10051_10143_10084_10083_10080_10082_10081_10110_10111_10112_10113_10114_130_10037_10032_10078_10079_10077_10073_10070_10123_10124,searchweb201603_4,afswitch_1,ppcSwitch_5,single_sort_0_default&btsid=2204374a-198b-4e82-af4e-a0d7348ef356&algo_expid=f5950bc5-8388-4842-bfec-157112b24ff1-0&algo_pvid=f5950bc5-8388-4842-bfec-157112b24ff1
3) Fit the bearing in the bottom bearing holder printed from the stl.
4) Open and remove one z axis motor and disconnect it from the motherboard, this also frees the driver for other use.
5) Now replace the motor with the bottom bearing holder assembled in the steps above.
6) Use the gab screws to secure the z-axis screw to the bearing
7) Print two sets of the pulley and their covers and fit together
8) Drive your z-axis to the top manually with your hand,
9) Fit the two pulleys and secure in place with two screws (pulleys with holes for screw and nut) pulleys are tight fit and will require some force to be fit.
10) Print and fit the two top bearing holders and fit the bearings in to them.
11) Fit these holders on top of the installed pulleys (see pictures for clarity)
12) With the z-axis now at top most (probably touching the installed pulleys) measure a length of timing belt to fit tightly and then reduce the length by about 3 teeth. The belt can be got from here Link:https://www.aliexpress.com/item/POWGE-GT2-timing-belt-width-6mm-Rubber-2GT-6mm-used-in-linear-drive-Small-Backlash-2GT/2039635559.html?spm=2114.13010608.0.0.TyqFC7
13) Now splice the belt to form a ring as per this procedure Link: https://www.youtube.com/watch?v=lT8eHz4tWyc
Notice that I did not use the kit i the video and I used standard leather glue, worked well. However, the procedure in the video produces a much cleaner result. Try it. You may also search for other splicing videos on Youtube. Its free, learn ;o)
14) Once the spliced belt cures lower the z axis down manually and fit the belt.
15) Drive the axis up manually again. Since the belt was reduced a bit (by about 3 teeth), the movement of the z-axis upward now provides full tension to the belt.
16) Tighten the Z-axis top bearing holders in place on the top rail to permanently secure the top bearing holders and tension the belt.
Modifying the Merlin Firmware:
17) Load your current firm ware in your favorite arduino IDE.
18) Open the file CONFIGURATION_ADV.h
19) look for the line below and comment it out (i.e. add // slashes before it as below)
20) //#define Z_DUAL_STEPPER_DRIVERS //Zahir - changed to use this driver for extruder 2
21) You may add custom comments as above to remind you in the future why you commented out the line.
22) It is done. Enjoy!