What is the purpose of the nylon filament?  

New Member

Hello to all,

I assembled the I3 MK3S last weekend.
In chapter   5. E-axis assembly   step  55 there is written from a nylon filament  50cm / 19.7inch.
This part wasn't  in my Kit and I finished assembling without it and the calibration was successful.

Please, who can explain to me where the part is for and whether the filament is important for printing.


Thank you in advanced


Posted : 16/03/2020 7:22 am
Honorable Member

The 3mm nylon filament piece should have been in your kit. See step 56 of the assembly guide for how it is fitted. Its purpose is to stiffen and support the cable bundle of the extruder to protect the wiring as it moves back and forth many times.

I would advise obtaining and fitting this part as it is recommended. As Prusa run several hundred of these printers they are well aware of areas that require mechanical assistance and this is a necessary part as I understand it.

You do not need to get the original part from Prusa if shipping would be an issue. The part is simply a length of 3mm black nylon filament which you should be able to obtain locally as a sample from a filament supplier.

Posted : 16/03/2020 7:39 am
Noble Member

As I learned from an earlier post - the nylon rod is a recent improvement to the Extruder cable bundle.

Earlier versions did not have it.

It is an important improvement, because it reduces flexing of the cable bundle at the extruder.

Flexing at that point will break wires, leading to hard to diagnose problems (nothing in this world is as bad as an intermittent break...).

I would not bother Prusa with this - any piece of 3 mm nylon filament will work fine.

Posted : 16/03/2020 5:48 pm

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