KOBRA XZ SWITCHWIRE REMIX

THIS GUIDE IS A WORK IN PROGRESS!!

For First Gen of Anycubic Kobra, *Kobra neo, *Kobra Go *= untested but upon observation the frame looks the same
 

I remixed the XZ gantry from the VORON Switchwire for the Anycubic Kobra. No need to cut X extrusion, no need to replace Z extrusions, I tried to make this as easy as possible without altering the original frame and re using the original hardware as much as possible. I bought a switchwire motion and hardware kit to make it easier than self sourcing(yes I have a bunch of stuff left over because there are no 3030 extrusions on this machine). It included all bearings belts and screws needed, I also repurposed as much hardware from the original machine. As of right now I using all steppers that came with the machine, I plan to upgrade later.

ALL PARTS PRINTED WITH VORON STANDARD SETTINGS IN ABS/ASA

Everything should be Oriented properly and not need supports, except the x carriage.

PULL APART YOUR X GANTRY/ REMOVE X and Z STEPPERS BEFORE BUYING HARDWARE TO SEE WHAT YOU HAVE AND CAN RE- USE

(Strip it down, remove and save all POM wheels and nuts/bolts/spacers) you just want the Z extrusions left. 

Remove the 4 bolts from the top of the Z extrusion crossmember. Measure and sort all screws by length to see what you can re-use. 

Right now the only carriage I have made is for the Mini Stealthburner/Dragonburner

                                                                       BOM

Using the original steppers: 

GT2 20T pulley x1

EVERYTHING ELSE BELOW as well: Except the two extra pulleys and 3 steppers

Using new steppers: 

Steppers x3

GT2 20T pulley x3

MGN12H linear rail 300mm x4

20 F695 bearing x20

GT2 Belt 6mm 1500mm x2

GT2 Belt 6mm 800mm x1

M5 1mm spacer x19

M5 T nuts for 2020 extrusions x7

M3 T nuts for 2020 extrusions x58 to fully populate rails

M5x30 SHCS x4  

M5x40 SHCS x4

M5x30 BHCS x4

M5x40 BHCS x6

M5x10 BHCSx3

M5x16 BHCS x1

M5 Hex nut x2

M3x8 SHCS x66

M3x6 SHCSx4

M3x8 FHCSx2

M3x30 SHCS x20

M3x40 SHCS x2

M3X16 SHCS x6

M3x12 SHCSx4

Makerbeam XL T-nut x2

M3 heatstake inserts x54

Key-bak super48 36 inch 13oz x1

Make sure you select a kit with rails

Threadlocker blue for grub screws

                                                                       ASSEMBLY

Go through and make sure all extrusions are square. Then, tighten all frame bolts (on outer left and right extrusions, underneath). Measure the distance between the inside of the outer extrusions and each side of the y-axis extrusion. If needed, loosen the y-axis and ensure it is as square and center as possible, then tighten.

On the back of the “Upper Right” bearing block, there is a mounting hole with threads for an M5x16 bolt and the key-back idler stack. Place two F695 bearings facing each other and then an M5 spacer and screw into the mounting hole, fully tighten.

Install the Upper Left and Right bearing blocks with 4 M5x30 SHCS and fully tighten, install bearing stacks and covers with two M5x40 BHCS and two M5 hex nuts (it helps if you use a large Allen key through the back of the blocks to hold the nut in place while you thread the stack). There are two mounting holes on the sides of the bearing blocks for M3x16 SHCS, slide the M3 T nuts on the outer V slots on the Z extrusions, up under the block until lined up with holes, and then fully tighten.
 

If using new steppers learn how they are wired and double-check your wiring before powering on.
 
Remove the Y stepper( it will be used on the XZ gantry if using stock motors). 

Install the new pulley on the old Z stepper. 

Don't fully tighten, and be sure to use blue Loctite. 

Install the Z stepper in the Y stepper mount. 

Figure out your Y-axis, install your linear rail/rails ( there are a bunch of different kits for the Kobra y-axis to install one or two rails), or do the remix I made. 
 
I've included a drilling guide that you bolt onto the bottom of your y-axis carriage and drill. 
 

Once drilled, use the linear rail positioning guide and loosely mount your linear rail on the right side of the y-axis extrusion. 
 

Mount your carriage with 4 M3x6 SHCS.

Install the front idler, the top holes line up with the old tensioner holes, and install two M4 BHCS on top and use two M5 T nuts and M5x10 BHCS on the bottom. 

Use an M5x40 BHCS for the idler shaft and your two bearings and spacers, use an M5 hex nut to snug them together loosely, and ensure the bearings can move freely
 

Install your Y motor mount with 3 M5 BHCS and 3 M5 T nuts. 
 

Install your belts and tighten slightly, run your bed back and forth, and watch the new pulley(center pulley on belt path and fully tighten). 

Install your bed and build plate and tram using the bottom frame and measure up and try to make it even on all corners.
 
Once you have the X gantry removed completely and are left with just the Z extrusions, go ahead and mount your two linear rails on the inside, using the alignment tool to ensure they are center. 

Measure up from the top of your bed with your choice of build plate attached, 25 mm, this is the height you want your Z rails to sit. 

This way if people's bed height differs the nozzle will still reach the bed fully tighten your rails starting from the center working your way out.

Using M5 for 2020 T nuts mount your rail stops tight to the bottom of the two rails.

Go ahead and heat stake all 4 holes on the backs of the Z bearing blocks, mount them to the linear rail carriages using 4 M3x30 SHCS for each block.

Using M3 for 2020 T nuts take your X gantry linear rail and mount it to one of the sides with a v slot, leave it slightly loose. 

Measure from the end of the rail to the end of extrusion on both sides, and get it center as possible, fully tighten from center out.

Mount the Left and Right XZ bearing stacks back plates tight to the rail with M3x8 SHCS in the hole closest to the linear rail and M3x8 FHCS in the outer holes (these holes are close to belts so SHCS have less clearance).

Now stack your bearings with the XZ cover plates and screw them to the back plates. 

I ended up swapping out the M5x30 for some M5x40 with nuts on the backs for extra strength, the original design just uses modeled threads.

Your X carriage is assembled and ready to be mounted to the Z bearing blocks using 4 M3 T nuts and 4 M3x30 SHCS (don't fully tighten).

With the gantry installed, slide your carriage to the top and touch the extrusion to the Upper Bearing blocks (try to keep square with blocks) hold in place measure from Z extrusions to ends of X extrusion, center gantry as best as possible, and fully tighten the 4 mounting screws. 

Slide your gantry up and down and check for binding (may need to loosen the Z rails and de-rack and adjust) once all binding is gone and rails are tight again do another check, and repeat this until there is smooth operation up and down with all bolts tightened.

Heatstake the key-bak back plate install the key-bak itself and cover the plate with two M3x12 SHCS. Remove the keyring.

Mount the key-back behind the right side Z extrusion using M5x10BHCS and M5 T nut.

(USE CAUTION WITH THE NEXT STEP)

If the key-bak slips out of your hand while mounting it can smack you!!

Pull the end of the key-bak up and over the Upper back side idler. Slide in the key-bak end in the end mount, mount to back of right side Z bearing block with two M3x12 SHCS.

Heatstake the two motor tensioners, screw in the two M3x40 SHCS. 

Assemble the motors( if you bought motors install the pulleys with correct spacing) If using stock motors youre going to use the X and Y motors(the ones with pulleys).

Remove the two upper frame bolts on each side of the outer extrusions,(I know it sucks but it all lines up right where these bolts are) I want to design some frame stiffeners for this but I haven't had any issues.

Using two M5x40 BHCS M5 T nut and Motor bolt spacers on each side, install the assembled motor mounts and motor mount spacer blocks, to each side of the outer extrusions, pull the motor mounts up as far as they can so when mounting the belt their is some slack. 
 

Leave them snug enough not to slide down and try to line them up close to their respective belt paths.
 

Heat stake the X carriage mount plate. Install the X carriage mount plate to the linear rail carriage with 4 M3x6 SHCS.

Heat stake the Toolhead carriage. 

Mount the Toolhead carriage to the mounting plate with two M3xSHCS.

Route the belts with motors in uppermost position, mount the belts to the Toolhead carriage with Two makerbeam XL T nuts and M3x16SHCS. Just snug enough you can pull on the belts and feel each notch. 

Put the carraige in the center. Try to pull on belts to get all slack out and look to have even tension throughout, make sure they are on the idlers. Tighten the two Makerbeam nuts fully. 

Tighten the two Motor tensioners till the belts feel sufficiently tight and wont slip off idlers( mine are kinda tight). 

Look at the belt path from the side and slide the motors until the belts look square and true.

Fully tighten the M5 motor mount bolts. 

Trim belts (leave a few notches to make it easier to remove Toolhead carriage if needed.

Move Toolhead and gantry around, nothing should be rubbing.

Im using a Biqu Microprobe inside the Toolhead Carriage.

Install the Toolhead of your choice(right now MINI Stealth and Dragon burner style toolhead will work).

Edit printer.cfg 

Kinematics to corexz

I have my Axis limits set as 

X max: 235

Y max: 195

If using probe, make sure it will trigger before your nozzle touches bed to avoid crashing.

If using sensor less homing I would set the SGTHRS value higher and work your way down to avoid crashing.

Reference the Voron website Switch wire manual/Github if you still have some questions. 

Leave a comment and I will try to answer it, please let me know what I can improve and please do remixes if you believe it can be improved.

OPTIONAL:

I added a lightbar that replaces the spool holder location. Two M4x8 screws if you lost them, and a rainbow matchstick that is used on Voron 0, might remix later to be able to mount the original holder back on top and maybe some ptfe couplers or something for a filament guide

link to the motherboard case im using:

https://www.printables.com/model/240112-btt-skr-mini-e3-v3-case

XZ lower bearing Icon source:

Snake Face by Iconic from <a href="https://thenounproject.com/browse/icons/term/snake-face/" target="_blank" title="Snake Face Icons">Noun Project</a> (CC BY 3.0)

I remixed the XZ gantry from the VORON Switchwire for the Anycubic Kobra. No need to cut X extrusion, no need to replace Z extrusions, I tried to make this as easy as possible without altering the original frame and re using the original hardware as much as possible.