Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)
 
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Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)  

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RonSound
(@ronsound)
New Member
Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)

I bought this printer used to use in my shop for printing small parts for myself.  The guy I bought it from said it was this model:

https://www.amazon.com/gp/product/B011PVIMPW/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1&fbclid=IwAR0lsm3JTciT0rABhyNcENZhoIe0T8yoMwqcL0El7lj6Nx4WdMiLzddqrTk

 

But I think it's actually this one:

https://www.amazon.com/RepRap-prusa-i3-V2-Printer/dp/B01HOVMLM2/ref=sr_1_14?crid=279EHLXUW906V&keywords=prusa+i3&qid=1656707759&s=industrial&sprefix=prusa+i3%2Cindustrial%2C125&sr=1-14

It looks a lot more like the 2nd link.  Anyway, I was replacing the nozzle and after I did I kept getting the MAXTEMP error.  Checked the resistance of the thermistor and it's definitely shorted out.  I'm having a hard time finding a replacement since I have no part # for it.  Does anyone know where I could find the correct part?  Also, is there another Prusa printer that it's similar enough to that I could use it's sub-forum for future help?

Posted : 03/07/2022 6:30 pm
JoanTabb
(@joantabb)
Moderator
RE: Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)

Also, is there another Prusa printer that it's similar enough to that I could use it's sub-forum for future help?

this printer looks similar to a Prusa Mk1 with a wobbly plastic frame. a mk8 Extruder and a RAMPS Controller board
there is so little commonality that I doubt you could use the Mk1 assembly guide as a reasonable guide for building this printer.. 

the Prusa firmware is unlikely to work with this printer because the controller types are different. the Minirambo from the Prusa Mk1, uses integrated stepper controllers, and electronic motor current setting, the RAMPS board for this printer uses manual adjusters on removable stepper drivers....  

One good thing about this is that you could probably use more up to date stepper controllers than the prusa mk1 used... 

I suggest that you have a look at TomSanladerer's youtube video's for (the cheapest Prusa Printer)  

(Note this relates to a mk2 printer, so the build volume would be wrong for you, and it probably uses a pinda probe which you don't have)
tom may have video's which are more similar to your needs

Info on Ramps 

If your printer is based on the model that you identified, then it is most likely that there is no cover for the powersupply power connections. this is a  significant safety hazard
when setting up steps per millimetre values this prusa website may help you 
https://blog.prusa3d.com/calculator_3416/
your printer seems to use common All Thread (Studding ) rods for the Z axis. this works, but is a poor option... proper lead screws are more commonly used. so please make sure toy find out what the pitch of the thread is! (Chances are that it will be 0.8mm... but you need to confirm this and identify the correct Z steps per millimetre. 
You also need to confirm what size the X and Y toothed gears are, Prusa  uses 16 tooth, most other printer manufacturers use 20 tooth gears (this will define the X and Y steps per millimetre that you will need to use. )
the Mk8 Extruder uses a larger hobbed gear than the prusa series printers, so you will need to estimate the 'E Steps per millimetre' probably, after assembly
this web page may help you 
https://all3dp.com/2/extruder-calibration-6-easy-steps-2/

MAKE SURE that you enable 'Mintemp', 'Maxtemp' and 'thermal runaway' safety checks, as an absolute minimum... 3d printers are not toys... 

Have fun. 

your task is not impossible, but the learning curve may be steep! 

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 : 03/07/2022 7:44 pm
JoanTabb
(@joantabb)
Moderator
RE: Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)

Oh, I completely forgot about the thermistor... 
Most 3D printers use 100Kohm thermistors, 
your printer probably uses the Bead type thermistor 
Like this 
https://www.ebay.co.uk/itm/191094757881?hash=item2c7e2299f9:g:iRIAAOSwa~BYYuHh

If you are configuring your own firmware, make sure to select the correct thermistor type in the configuration.

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 : 03/07/2022 7:50 pm
RonSound
(@ronsound)
New Member
Topic starter answered:
RE:

Thanks for the info.

Here's the thermistor I have. 

This post was modified 1 month ago by RonSound
Posted : 03/07/2022 8:06 pm
JoanTabb
(@joantabb)
Moderator
RE: Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)

that looks like a cartridge thermistor, so something like this may well work!

https://e3d-online.com/products/prusa-specific-thermistor-mk2-mk3?_pos=2&_sid=bba8db486&_ss=r
or
https://www.amazon.co.uk/HzdaDeve-Thermistor-Temperature-Degrees-Hot-End/dp/B0951Y47HQ/ref=sr_1_17?adgrpid=61630896708&hvadid=606112409026&hvdev=c&hvlocphy=1007230&hvnetw=g&hvqmt=e&hvrand=12457765086384555875&hvtargid=kwd-300793143351&hydadcr=14560_2301032&keywords=100k+ntc+thermistor&qid=1656926924&sr=8-17

 

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 : 04/07/2022 9:31 am
RonSound
(@ronsound)
New Member
Topic starter answered:
RE: Looking for new thermistor for RepRap Guru prusa i3 V2 B(?)

Well, it turns out the picture I posted was actually the heating element.  The thermistor was next to it.  I disconnected it and measured the resistance and it was fine.  Tried a print and it heated up fine.  Nothing printed but at least I'm making progress.

Posted : 09/07/2022 8:42 pm
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