V1.8 12mm mod by eddie (#127)

printer_mods/README.md

@@ -31,6 +31,7 @@ like so:
 |Dan88 |[V0 one-part Skirts](./Dan88/V0skirt) |One part Skirts for the V0 |:heavy_check_mark: |:x: |:x: |
 |DorjeDorf | [Duet 3 6HC Din Bracket](./DorjeDorf/Duet_3_6HC_Din_Bracket) | V2.4 Duet 3 6HC Din Bracket | :x: | :x: | :heavy_check_mark: | 
 | |[Duet 3 3HC Din Bracket](./DorjeDorf/Duet_3_3HC_Din_Bracket) |  V2.4 Duet 3 3HC Din Bracket | :x: | :x: | :heavy_check_mark: | 
+|eddie |[V1.8 12mm Z Mod](./eddie/V1.8_12mm_Z_Mod) |Add V1.8 option for 12mm Z rods |:x: |:heavy_check_mark: |:x: |
 |edwardyeeks |[Decontaminator Purge Bucket](./edwardyeeks/Decontaminator_Purge_Bucket) |Removeable purge bucket |:x: |:x: |:heavy_check_mark: |
 | Ellis |[15x15 Drag Chain Ends](./Ellis/15x15_Drag_Chain_End) | 15x15 drag chain end pieces | :grey_question: | :grey_question: |:heavy_check_mark: |
 | |[Badge Retractor Mount](./Ellis/Badge_Retractor_Mount) | Extrusion mount for badge retractor to keep bowden tube out of the way. | :grey_question: | :grey_question: |:heavy_check_mark: |

printer_mods/eddie/V1.8_12mm_Z_Mod/README.md

@@ -0,0 +1,11 @@
+<B>Voron 1.8 Z Mod - 12mm</B>
+
+This replaces the 4x 8mm rods and 4x LM8LUU bearings with 12mm rods and LM12LUU bearings. I did this modification to a printer to see if I could tell the difference, but I couldn't see any clear difference. However, if you do, let me know!
+
+Note that the top and bottom retainers shaft retainers are different--the top ones are slim (with a thin wall) as they need to clear the XY joints. The lower retainers have a bit more material on them.
+
+Finally, as the 12mm rods are thicker and are shifted towards the center of the printer (to clear the side panels), the sideways bed extrusions that attach to the Z bearing blocks must be shorter by at least 6mm per side. If you are hand cutting the extrusions, consider cutting an extra 1-2mm off to allow clearance.
+
+![Overview](Images/12mm_Z_Mod.png)
+
+![Cross_Section](Images/Cross_Section.png)