CR-10 Dual Z with top mounted stepper by StvPtrsn

Last crawled date: 3 years, 1 month ago

Last Fall I purchased and installed the dual Z upgrade for my regular CR-10. For weeks I fought bed leveling with the steppers going out of alignment for whatever reason. Drawing inspiration from Caster's Youtube video (thing 2569379) I set out to design my own belt driven dual Z setup. I completed it and published it as thing 2628377. Having used it for the past 4+ months I have to say this is the best modification I've done to my CR-10. Where I used to re-level the bed after almost every print, now I only do it when I change build surfaces.
One of the problems with the previous design was that it over constrained the left side lead screw. I spent a lot of time with a set of calipers and a straight edge making sure the z stepper and the upper bearing mounts were lined up perfectly with the lead screw nut so this wouldn't actually cause print problems.
My new design is an attempt to resolve that problem. With this setup the Z stepper is relocated to the top of the frame and the lead screws are allowed to float at the bottom. As before I do not like driving set screws into the threads of the lead screws so I spent the effort designing alternative ways to attach the pulleys :)
I secured the wiring extension with 1" lengths cut from the extrusion inserts that came with the printer. If you split them down the back side they will wrap around the wiring and allow you to secure it in the frame slots. There is plenty of room to run this down the right extrusion and the X carriage bracket clears it without problem.
Parts list (for CR-10S):
BIQU GT2 Synchronous Wheel 60 Teeth 8mm Bore Aluminum Timing Pulley for 3D Printer 6mm Width Belt (Pack of 2pcs)
Link: http://a.co/eORAb49
BIQU GT2 5mm Bore Aluminum Toothless Timing Belt Idler Pulley for 3D Printer 6mm Width Timing Belt (Pack of 5pcs)
Link: http://a.co/2LMLfJs
BEMONOC Pack of 2pcs GT2 Driver Belt 900-2GT-6 Timing Belt in Closed Loop Rubber L=900mm W=6mm 450 Teeth
Link: http://a.co/1px2mDt
Qunqi 5PCS Aluminum GT2 Timing Belt Pulley 20 Teeth Bore 5mm Width 6mm and Wrench for RepRap 3D Printer Prusa i3
Link: http://a.co/hLGLZjm
20-Pack 608 ZZ Ball Bearings , 608zz Metal Double Shielded Miniature Deep Groove Skateboard Ball Bearings (8mm x 22mm x 7mm)
Link: http://a.co/6dibLpCAny 608 bearing should work since we are not putting a heavy axial load on these. The ones linked above specify "deep groove", I'm not sure if all 608s have the same groove or not. The bearings I used I bought for fidget spinners and did not specify they were deep groove.
You'll also need some way to extend the stepper wiring. I have a CR-10 harness extension kit so I just used the Z wire out of that.
*in addition to these parts a standard CR-10 will require a second lead screw and right side bracket. Since I bought the dual Z upgrade I have not needed to model the right side bracket.
Hardware:
(2) M5x20 screws for the stepper mount idlers. Just thread them into the plastic.
(2) M5 washers for under the stepper idlers to keep them from rubbing on the mount
(4) M5x8 screws with t-nuts to attach the stepper mount to the frame
(4) M4x20 screws with t-nuts for mounting the bearing brackets to the frame
(4) M4x6 button head cap screws with the head filed down to about 6.5mm diameter (chuck it up in a drill and run it over a file) These are only if you are using the 60T pulley adapters provided. Alternatively just use the set screws.
(4) M3 locknuts for Below_Bearing_Clamp_x2 and 8mm_60T_GT2_Clamp_x2
(4) M3x10 for Z_Bearing_Mount_x2. They screw into the sides to lock the bearing in place.
(4) M3x10 to attach the stepper motor
(4) M3 washers for the stepper motor screws
(2) M3x12 for Below_Bearing_Clamp_x2
(2) M3x20 for 8mm_60T_GT2_Clamp_x2
Firmware changes are required. You can do this at least two ways.
Edit Marlin 1.1.8 line 532
define DEFAULT_AXIS_STEPS_PER_UNIT { 80, 80, 400, 101 }
Change the 400 to 1200
or
From a terminal send commands:
M92 Z1200 to set the Z steps/mm then M500 to save the setting
Note: You will likely lose some Z height with this modification depending on how your x carriage wiring is set up.
Please let me know if you build this. I'd like to hear how it works out.