Exposed wire but printer works fine? How should I fix this?
 
Notifications
Clear all

Exposed wire but printer works fine? How should I fix this?  

  RSS
AWilling
(@awilling)
Active Member
Exposed wire but printer works fine? How should I fix this?

I have been printing a lot over the past few days, so noticing that a thin brass wire was exposed caught me offguard.  I took the attached picture while the unit was running; nothing bad seems to be happening.  Picture is a bit blurry from digital zoom and the extruder movement, but the copper color wire should be easily noticeable, just near/outside of the white covering.

 

I'd prefer to NOT replace that entire assembly, especially since things seems fine.  Any recommendations on a good way to fix this?  Can I just slip it back inside the sleeve (somehow)?  Use a small zip tie around it and the red-sleeved wires to eliminate that sag?

Anyone else experience anything similar?

Posted : 23/03/2022 2:19 am
Neophyl
(@neophyl)
Famed Member
RE: Exposed wire but printer works fine? How should I fix this?

Damage there is usually caused because the wires haven't been positioned properly during assembly.  When too low they can catch on the left steel plate stop and cause abrasion.

Thats the thermistor so its in the hot zone.  So yes when cold try and move the sleeve down.  If you cant then a high temp resistant sleeve could be slipped over both wires (remove the thermistor from the block by loosening the tiny grub screw, slide it over the whole assemble and refit.  That way you wouldn't have to remove the whole wiring loom.

Also I'd acquire a spare now.

Posted : 23/03/2022 7:00 am
AWilling
(@awilling)
Active Member
Topic starter answered:
RE: Exposed wire but printer works fine? How should I fix this?

Thanks @Neophyl.   The wires were definitely positioned properly during assembly two years ago, but over time they must have wiggled and loosened.  Anyhow, I got a new picture: the sleeve is clearly ripped, and there's no "sliding it back over," as the rip is quite long, and the sleeve doesn't really move at all, either.  I did manage to push the wires up a bit higher, and used a separate zip tie at the outlet to re-secure them in this position.

You said this is the thermistor?  So, basically a temperature sensor?  I assume that if it fails, the system will fail-safe?  If not, how much of a safety risk is this?  I dread replacing this not because of the hotend, but because the sleeving of the bundle of wires is tedious. 🙁

Also, when you say purchase a spare, do you have a recommendation?  Or, are all of these the same?

Posted : 23/03/2022 12:40 pm
Neophyl
(@neophyl)
Famed Member
RE: Exposed wire but printer works fine? How should I fix this?

Off hand I cant remember if an open circuit on a thermistor give max or min temp readings.  It will basically give you a max temp or min temp error if it breaks.  SO the printer should fail safe into an inoperative mode.  Which is why I suggested getting a spare now.  Less down time that way.

The thermistors are available from a wide variety of sources but there are different types so you want to make sure you source a compatible one.  Even then I'd personally go with a decent supplier/brand as you never know if the really cheap ones are going to give quite the same response curve as a decent one.

They are the same type as a standard E3d V6 hotend (which is what's fitted to the MK3).  I believe Printed Solid is a decent supplier in the US.  I've seen them recommended by forum members here before, although I have no personal experience with them.  Depend where you are in the world though.  As I'm in the UK I have bought spares direct from E3d. 

Not related to your problem but the last time I rebuilt my Mk3 I used their wiring as they fit connectors closer to the actual sensor.  I can replace mine without doing a loom replacement.  I similarly fitted connectors for all the hot end parts and fans during my rebuild so I can replace any part without taking it all apart now.  So yeah I know how painful that wiring bundle is having done it a few times before I modded it.

Posted : 23/03/2022 2:22 pm
AWilling
(@awilling)
Active Member
Topic starter answered:
RE: Exposed wire but printer works fine? How should I fix this?

Thanks!  I like PrintedSolid.  I think this one will work; I hope the modifications needed to fit it into the MK3S aren't too onerous.  I see there's a straight-up MK3S compatible one, but I prefer the adapter for easy replacement in the future.

https://www.printedsolid.com/products/e3d-thermistor-cartridge?_pos=1&_sid=7bd59333e&_ss=r

I'll consider a mod like yours when I have to unravel the entire thing; right now, I think I'll try something ugly yet serviceable. 🙂

Posted : 23/03/2022 2:59 pm
Neophyl
(@neophyl)
Famed Member
RE: Exposed wire but printer works fine? How should I fix this?

Yeah thats the standard e3d one.  Its the one I fitted.  Just have to make sure the extra connector doesn't get in the way.

Posted : 23/03/2022 3:09 pm
Share: