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Wire fatigue from spiral wrap? - Burnt cables  

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dryja123
(@dryja123)
Honorable Member
Wire fatigue from spiral wrap? - Burnt cables

Hello all,

Wondering if you've noticed any wire fatigue / damage from the spiral wrap on your extruder cable bundle. I took off the spiral wrap on my cable bundle today and noticed several spots on my heater cartridge cable that looked burnt / worn down.

Photos: https://imgur.com/a/P3hHhqu

I mentioned this to a buddy of mine and he took the spiral wrap off of his MK3 and it looked like his heater cartridge cable sleeve was being shaved by the spiral wrap.

I contacted Prusa support and they're sending out a new heater cartridge.

Has anyone else noticed this? Do you think it's an issue with the spiral wrap? What're your thoughts?

Posted : 17/05/2018 12:21 am
Cowwolfe
(@cowwolfe)
Active Member
Re: Wire fatigue from spiral wrap? - Burnt cables

My fan wires went bad twice (the red/black/yellow combo). One time it was the yellow, the other time the red. My MK3 was purchased pre-assembled. Fortunately, the cable and fan were under warrantee. After the second replacement, I opted to put a connector on each end of the cable wrap. The next time it breaks, I only have to remove the broken section in the middle and won't need to disassemble part of the head to swap out the fan.

In my experience with industrial robots, this cable wrap is not the best. A cable track would be better, but you would probably need to replace the cables as they would be too short IMHO to make the route well in a cable track. I've seen several case on Thingiverse where people have created cable tracks and mounts for both ends.

Eric Z....
Posted : 17/05/2018 1:52 am
dryja123
(@dryja123)
Honorable Member
Topic starter answered:
Re: Wire fatigue from spiral wrap? - Burnt cables

Thanks for the feedback, I was considering using heat shrink tubing but wasn't sure if there's a bigger issue that's causing the damage. I decided to take the cautious route and replace the cables because the heater cartridge wires carry a lot of voltage.

Posted : 17/05/2018 2:07 am
JoanTabb
(@joantabb)
Moderator
Re: Wire fatigue from spiral wrap? - Burnt cables

Hi Corey, I used Braided cable sheathing instead of spiral wrap

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 17/05/2018 2:45 am
dryja123
(@dryja123)
Honorable Member
Topic starter answered:
Re: Wire fatigue from spiral wrap? - Burnt cables


Hi Corey, I used Braided cable sheathing instead of spiral wrap

regards Joan

HI Joan, thanks for the tip! I was talking to my friend about using braided wire loom VS spiral wrap and was concerned about rigidity. I'll give it a go

Posted : 17/05/2018 3:16 am
thrawn86
(@thrawn86)
Honorable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

[/quote]
I decided to take the cautious route and replace the cables because the heater cartridge wires carry a lot of voltage.

The teflon insulation isn't even exposed, its not electrically compromised at all. Tiny bit of heatshrink or electrical tape is all you need.

Posted : 17/05/2018 6:36 am
dryja123
(@dryja123)
Honorable Member
Topic starter answered:
Re: Wire fatigue from spiral wrap? - Burnt cables



The teflon insulation isn't even exposed, its not electrically compromised at all. Tiny bit of heatshrink or electrical tape is all you need.

Still haven't figured out why it looks the way it does. It's all over that cable in multiple spots.

Posted : 17/05/2018 6:52 am
Calire
(@calire)
Honorable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

Hello.
It is possible to see or explain the difference between "spiral wrap" ( i think that is the model mount with the kit) , "cable track" and "Braided cable sheathing".

And about textile sleeve with reinforcement at the start and the end ? too light and too soft to maintain the set of cables ?

Posted : 17/05/2018 8:19 am
thrawn86
(@thrawn86)
Honorable Member
Re: Wire fatigue from spiral wrap? - Burnt cables




The teflon insulation isn't even exposed, its not electrically compromised at all. Tiny bit of heatshrink or electrical tape is all you need.

Still haven't figured out why it looks the way it does. It's all over that cable in multiple spots.

If there was enough heat somewhere to melt the fiberglass you'd have a much bigger problem on your hands. It has to be mechanical.

Posted : 17/05/2018 6:47 pm
motocoder
(@motocoder)
Trusted Member
Re: Wire fatigue from spiral wrap? - Burnt cables


Hello.
It is possible to see or explain the difference between "spiral wrap" ( i think that is the model mount with the kit) , "cable track" and "Braided cable sheathing".

And about textile sleeve with reinforcement at the start and the end ? too light and too soft to maintain the set of cables ?

This is Spiral Wrap:

And this is braided wrap (this kind is actually called "Split Tube", because it has a seam that allows you to insert the wires in the side. There is also just the regular braided wrap that requires you to fish the wires through. There's also a kind that has a good bit of stretch to it that makes it easier to do that if the wire already has connectors on it.

Posted : 18/05/2018 7:56 pm
motocoder
(@motocoder)
Trusted Member
Re: Wire fatigue from spiral wrap? - Burnt cables


Hi Corey, I used Braided cable sheathing instead of spiral wrap

regards Joan

Joan - what size braided wrap did you use? Was it the "split tube" variety, or did you have to fish the wires and connectors through?

Posted : 18/05/2018 8:23 pm
Calire
(@calire)
Honorable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

Thank you Matthew.
I know the 2 model but ignorant about the name ; i feel better with english langage now.

Posted : 18/05/2018 9:30 pm
dryja123
(@dryja123)
Honorable Member
Topic starter answered:
Re: Wire fatigue from spiral wrap? - Burnt cables



Joan - what size braided wrap did you use? Was it the "split tube" variety, or did you have to fish the wires and connectors through?

Not Joan but 3/8 should be sufficient.

Posted : 18/05/2018 10:20 pm
JoanTabb
(@joantabb)
Moderator
Re: Wire fatigue from spiral wrap? - Burnt cables

I cut the braided tube very long, expanded it and fished the wire ends through, then tucked the frayed ends back inside, for a distance longer than the fixing piece in the back of the X axis, to make the ends tidy and create a short section of slightly stiffer re enforcement as the wires leave the fixing piece on the back of the X axis.

I included the nylon filament inside the braiding, most of the way, but where the braiding was going to disappear inside the Einsy case, I eased the nylon between the strands of braiding, so that the nylon could still go into the receptacle, as the braiding went inside the case. and I cable tied both ends securely.

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 18/05/2018 10:58 pm
martin.f3
(@martin-f3)
Eminent Member
Re: Wire fatigue from spiral wrap? - Burnt cables

This explains what happened to me. Not long after upgrading to mk2.5 my heater stopped working mid print and I noticed one of the cables to the heat cartridge was off 🙁 i ordered a new one and replaced so will try rerouting cables a bit now.

...
Posted : 20/05/2018 1:18 am
Robin
(@robin-4)
Estimable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

I have just found the cable damage on the heater wires on my mk3. The part cooling fan has by the looks of it got a broken wire due to cable flexing. Although it was under no stress, kinked or tie wrap tight. So when I removed the spiral wrap the heater wires were worn in about 3 places on both wires.

I have ordered a new fan but may just fix the broken wire, if I can find the spot it’s broken.
I is definitely worth changing the hard spiral wrap out for a different type. For now I’ll just have it tie wrapped until I have a solution to the problem.

Posted : 26/06/2018 1:26 pm
Robin
(@robin-4)
Estimable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

Found the wire break quick than expected. In the photo I have wrapped a black wire around the part cooling fan wire at the point of the break.

This matches up to the wear marked on the heater element wires. So it’s definitely the hard spiral wrap that is causing issues.
Has this been changed in later versions to the softer wire wrap?

Posted : 26/06/2018 1:44 pm
dimprov
(@dimprov)
Noble Member
Re: Wire fatigue from spiral wrap? - Burnt cables

If a short does develop, will a fuse blow, or will it just melt and maybe catch on fire?

Posted : 26/06/2018 8:24 pm
Martin Wolfe
(@martin-wolfe)
Reputable Member
Re: Wire fatigue from spiral wrap? - Burnt cables

See my reply on this subject in Robin's thread Part cooling fan wire repair.

Martin Wolfe...
Posted : 27/06/2018 2:09 am
robert.t17
(@robert-t17)
Eminent Member
Re: Wire fatigue from spiral wrap? - Burnt cables

After having problems with the PINDA cable, I replaced the spiral wrap with this.
https://smile.amazon.com/gp/product/B004UHQMYW/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
I wraps around it's self so no slot for wires to drop out.

Posted : 27/06/2018 1:14 pm
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