June 15, 2026
Description
Add this badge to your Core ONE to commemorate replacing the main cable, in your choice of MAIN CABLE or HLAVNÍ KABEL. The hard part of adding this skin to your Core ONE is the work on the inside.
Background: I had to replace the main cable on my Core ONE. When I asked Prusa support where the instructions were they said "use the main assembly instructions" which wasn't as helpful as it could be since they're backwards and include other steps interleaved. So, as I was doing the replacement and figuring out what to do, I took notes so other people could benefit from my experience. I couldn't just post the instructions without — what else — a commemorative badge you can print out to go with the rest of your Printables badges. (Note that I'm posting this as a model, not as an article because articles are harder to find than models.)
If you've already replaced the main cable, skip directly to part three for instructions for printing your badge.
If you built the Core ONE kit, you're basically going to reverse the steps you did in installing the cable and then repeating the steps to install it again. It's a bit more complicated as there's more stuff in the way. Also you can print the I BUILT THIS badge to go along with this one. https://www.printables.com/model/1729673-i-built-this-postavil-jsem-printables-style-badge
If you bought an assembled Core ONE, you're going to get part of the kit experience for the first time. Take your time and enjoy learning some of the internal assembly details of your printer.
The torx screwdriver and 2.5mm allen wrench that came with your Core ONE.
Flush cutters or side cutting pliers.
[OPTIONAL] Painter's tape to keep the screws with the parts you remove. (In some cases you can lightly rethread the screws into the parts instead.)
[OPTIONAL] Rivet removal tool. I recommend an unsharpened pencil with an eraser to push them out and this tool to remove them: https://www.printables.com/make/3375191.
You're also going to want to have the assembly guide handy https://prusa.io/coreone https://prusa.io/core-one-plus.
I've linked to the corresponding part of the assembly instructions where you can find relevant pictures. You can mostly ignore the instructions there since you're doing them backwards. (Note that sometimes it's easier to not do them strictly in reverse order since you're not reverting all of the steps.)
Use the Control menu (Control > Axis > Z) to position the heat bed about two thirds of the way down. You want it low enough so that it doesn't get in the way and high enough that you can reach underneath in case you drop a screw. Put a box or some kind of pad on the print bed to protect it.
Turn the power off and unplug your Core ONE.
Remove the door. Highly recommended because the door will likely get in the way and you don't want to accidentally break it! Hold the door while you loosen the screws and then remove the two middle screws, then the bottom screw, then the top screw. [8.46]
Remove the top cover. You want to be able to reach in from both the front and the top. Remove the rivets by first pushing them out from the inside. then pulling them out from the outside. Remove both the pins and the collets. Set the cover aside. [8.8]
Position the printer so you can access it from the front and the back. Depending on your work surface you may need to rotate the printer around a few times as you work.
Read Prusa's instructions about protecting components from electrostatic discharge and be careful whenever you're touching the electronic components including plugging or unplugging cables.
Remove the buddy box cover by unscrewing the six screws holding the cover on. [7.33]
Remove the rear cover (above the PSU and buddy box) by unscrewing the two screws on the inside of the Core ONE holding it in place. You'll have to tilt it as you remove it. [7.34]
Unplug the main cable from the xBuddy board. [7.56] All the cable connectors you'll be unplugging have a locking tab which you need to gently depress to unplug them.
Carefully cut the zip ties around the cable. Use flush cutters or side cutting pliers. Do this for all the zip ties that attach the main cable to any other cables on the back of the printer. (If you left the zip ties loose you may be able to slide the cable through some of the zip ties without cutting them.)
Carefully feed the main cable back through the hole at the top of the buddy box. [7.56] It's easier if you slide the grommet off and up and then replace it afterwards. Leave the cable loose for now and turn the printer around.
Position the printer so you can access it from the front.
Remove the left and right Nextruder covers (one screw on the left, two on the right). [6.55]
Remove the two fabric cable ties closest to the extruder. [6.42]
Slide the bowden bend up the bowden cable and unscrew the M5-4 fitting on top of the Nextruder, using the universal wrench if you need to. [6.41]
Unplug the print fan cable and unscrew the fan shroud from the front (do not remove the screws holding the fan to the shroud). Remove the fan and shroud. [6.46]
Unplug as many cables as you can from the loveboard. (If you can't unplug some you'll have to do that after you remove the loveboard assembly.)
Unscrew the two screws on the back at the bottom of the loveboard assembly using the 2.5mm allen wrench. [6.38]
Remove any remaining connectors plugged into the loveboard except the main cable and remove the loveboard.
Remove the remaining three fabric cable ties connecting the main cable, bowden tube to the swing arm. [6.40]
If you assembled the kit, remember how hard it was to connect the main cable clip? It's a little bit easier in reverse. Unscrew the clip and then carefully feed the cable back through the hole being careful not to dislodge the grommet. (You can't lose the grommet but you don't want to have to fish it back from inside the printer.) [6.36–37]
Unscrew the loveboard mount. Be careful not to lose the two screws that are loosely in between the mount and the mount. [6.38]
Unplug the cable from the buddy board and remove the cable.
Congratulations! You're halfway there. Celebrate by enjoying some of your favorite candy (you're not limited to Haribo bears).
Now you're going to basically undo what you just did. Since Prusa has instructions for installing the cable as part of the kit build, I'm going to link to those instructions. I'll highlight here things that are different.
To avoid getting the old and new cables confused, put a piece of painter's tape around the old cable and write OLD on it. Put the tape next to the main cable clip so you can use the tape to align the cable clip on the new cable.
Match up the two cables making sure that you match the two ends with the white label. (The length of the textile sleeve is also different on the two ends.)
Transfer the cable clip to the new cable by removing the screw and gently opening the clip. Slide the clip off the old cable and onto the new cable in the same position and orientation. [Prusa really should send a replacement of this part when they send a replacement cable as it's breakable.]
Set the old cable aside.
Do steps 6.31–36. Skip any steps that are already completed like attaching the bowden tube.
At this point you should feed the cable through to the back of the printer. This is step 6.55 but it's easier to do it now. The instructions say to feed it through the top hole. But the bottom hole is unused and, if you have a spare grommet, it's a lot easier to feed it through the bottom hole instead (especially since, if you assembled the kit, the first time you did this you hadn't attached the right side panel yet). Carefully feed the cable through without the grommet, then slide the grommet onto the cable and put in place in the hole. Pull the cable through and make sure you have enough to connect it.
Continue with steps 6.36–56. In the last step, add new zip ties to replace any that you cut. You can use another zip tie to guide the new zip tie under and around the cables.
Continue with steps 7.32–34.
Plug the printer in and make sure it powers up when you turn it on. You can use the Control menu to move the axes as a preliminary test.
Run calibration and tests, steps 9.8–13, to make sure everything is working. You'll need to bypass the door sensor to do this before reinstalling the door (Settings > Hardware > Door Sensor). If you're worried about doing this, note that the MKx models don't have enclosures and you would run calibration and tests without a door. (And the reason to delay reinstalling the door is just in case, you have to go back and adjust something.)
Reinstall the top cover, step 8.8. If you're reusing the rivets, you want to insert the collet first and then the pin.
Reinstall the door, step 8.46. Turn the door sensor back on.
Print your commemorative badge (next part below). Have some more of your favorite candy while the badge is printing.
If you find an mistakes or think any step needs more detail, please let me know and I can revise it.
The badge is designed for filament changes so you don't need an MMU or INDX to print it. I recommend printing in black, gray, white, and orange.
Start with black.
Switch to gray at the bottom of the border.
Switch to orange just above the border.
Switch to white at the bottom of the lettering.
While it looks cool on the inside next to the main cable, I don't recommend printing with it there. Better to put your badge on top of your printer or anywhere that works for you, maybe with your other Printables badges.
License:
Creative Commons — Attribution — Noncommercial — NoDerivatives
7
Mondegrue
