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Heatbed thermistor wire breaking  

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Richard D
(@richard-d)
Trusted Member
Heatbed thermistor wire breaking

And that's my second broken wire in four months.  I'm running my printer about 20 hours a day, so every 1,000 hours or so the heatbed thermistor wire has fractured, causing the MinTemp error and a failed print 🙁

Are we supposed to treat these things as disposable items, in need of regular replacement like car oil filters?

Or could Prusa be persuaded to upgrade the part with a wire that is fit for purpose?

I'm going to see what I can do to improve the strain relief on that cable (I printed all the parts BEFORE the machine failed, knowing that it was only a matter of time), but it shouldn't really be necessary to Heath Robinson a fix for the issue 🙁

Posted : 09/07/2021 6:28 am
cwbullet
(@cwbullet)
Member
RE: Heatbed thermistor wire breaking

I used something like this:

https://www.prusaprinters.org/prints/50799-prusa-mini-heatbed-connector-cover-48deg-longer

If your printer is in an enclosure, it can be from hitting the back wall while printing.  I have 5 of these printers and have never had a broken wire.  I did have it on my MK3Ss.  On my Mk3Ss, I installed a 3mm piece of nylon filament to avoid bends in the wires.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 09/07/2021 12:42 pm
Richard D
(@richard-d)
Trusted Member
Topic starter answered:
RE: Heatbed thermistor wire breaking

@cwbullet

Yep, been using something like that since the last thermistor wire broke.  I've now installed an even better version.

Nope, my Mini isn't in an enclosure, and nothing is hitting the wire.  It's just breaking with the constant flexing.  I am using the machne pretty much constantly, 24/7.  Hopefully this one lasts a bit longer.

Posted : 09/07/2021 12:55 pm
cwbullet
(@cwbullet)
Member
RE: Heatbed thermistor wire breaking

@richard-d

I have 5 running around the clock without a broken wire.  It must be something different with the use or machine.  

Care to share your design for the wire stress relief?

--------------------
Chuck H
3D Printer Review Blog

Posted : 09/07/2021 1:16 pm
djkirkendall
(@djkirkendall)
Trusted Member
RE: Heatbed thermistor wire breaking

I tried putting all 36 of mine in PETG chains, and I've had a break on thermistor line close to the cap screws retaining the HB power wires in almost every instance. I go through 1-2 a month with 16 machines running 24/7. 

I'm considering redesigning that lower retaining mount on the HB cable to allow for an alternate path for the HB therm that isn't so close or pinched by the cap screw.  

Posted : 09/07/2021 8:04 pm
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