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Add a washer to the screw, to avoid damaging the printed part.
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Insert the screw through the hole on the opposite side to the hexagonal cavity.
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Thread the hex nut onto the screw and tighten the screw.
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When the nut is fully seated, remove the screw being careful not to dislodge the nut.
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The printed parts for the extruder include a PTFE tube cutter tool that matches the specifications required for the Bear extruder. The part name is ptfe_cutter_50mm_60deg.stl
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Follow this guide to prepare the PTFE tube Trim PTFE Tube.
In this description, it is a little ambiguous as to whether we should or shouldn’t use a tube from MK2.5S. I’m guessing the answer is no, but I’d recommend clearing it up. “If you have a PTFE tube from MK2S, MK2.5 or MK2.5S that is not too much damaged you can then reuse it.”
Thank you for reporting this, we have fixed it, hope it is clear now.
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Take the time to check your newly printed parts:
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Clean up strings with tweezers and a hot air gun (be careful).
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Carefully check inside the holes of the X ends, where the smooth rods will be inserted.
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Remove any elephant foot with a deburring tool.
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Check all bridges. If a bridge is falling in its center: heat tweezers with a lighter(or use a soldering iron) and press on the area with the poor bridging, to make it more flat.
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Make sure the filament path through the extruder body is clean, round, and clear from obstructions.
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1. Unload the filament and allow the hot end to cool. Turn off the printer and remove the power plug.
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2. Protect the printing surface and use a tray to catch small components that might fall during the disassembly.
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3. Remove the M3x40 screw securing the Rambo/Einsy cover and disconnect all the plugs, from the board that make up the extruder cable bundle.
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4. Cut the zip ties and remove the screws clamping the extruder cable to the Rambo/EINSY box and remove the 3mm nylon filament. Completely unwind the spiral/fabric wrap from the cables.
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5. Cut the zip ties securing the extruder cables on the cable guide and remove the cable wrapping. Untangle the wires.
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6. Unscrew and remove the cable guide.
For MK3s: You must also remove the cable guide from the extruder before you are able to remove the x-ends/axis (in the next step)
Thanks, fixed!
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1. Remove the screws holding the z-tops in place.
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2. Pull the z-tops off the smooth rods. Try to avoid pulling the rods from the z-motor mounts. If a rod does come loose, avoid rotating it within the linear bearings.
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3. Remove the screws, securing the trapezoidal nuts to each x-end and spin those nuts to the top of the lead screws and remove them. They will be reused.
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4. Lift the x-ends off the z-axis rods by lifting both the motor and idler mounts evenly.
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5. MK2.5(S) only: Remove the two M2x12 screws securing the x-end limit switch.
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6. Remove the three screws holding the x-end motor.
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7. Pull the rods out of the x-end-motor and idler mounts taking care not to bend or twist the rods.
For Mk3s: It makes more sense to remove the timing belt (next step) before removing the 3 screws on the motor mount
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1. Cut the zip ties holding the extruder assembly to the linear bearings.
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2. Remove the timing belt. Replace if worn or damaged.
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3. Carefully pull the wires through the x-end assembly
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4. Tear down the entire extruder by reversing the assembly instructions provided by Prusa.
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5. All the printed parts will be replaced. Most of the electrical parts and fasteners can be reused.
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6. Check all wires and connectors for possible damage especially where wires had made a tight bend or may have been clamped too tightly.
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7. If you already have the PFTE tube at the correct length, check it for possible damage.
For MK3s: Remember that you will NOT be re-using the ptfe tube. You have to re-cut a new one!
Thanks, updated!
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Congratulations you have finished this step and are ready to start re-assembly :-)
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Got to the next chapter: 2. X axis
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One Comment
All in all the instructions were great! A few small inconsistencies with my MK3s extruder for your stepwise instructions but they were simple to figure out…