Whats wrong with this picture - printre hot ends

So was swapping hot ends to a different nozzle diameter and noticed the thermistor bead is just loose and in poor contact with the heat block. Same on all the other extra hotends I bought. Surprising given the quality in the rest of the machine.

So Id recommend some epoxy or high temp stud thread lock…

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Son muy delicados en cuanto los obligas un poco se despegan el extremo parece de cristal saludos.

same with mine, where did you get two extras ?

I bought the extas pack prior to delivery… had extra heat bed, 3d printing nozzles and CNC bed. You could quite easily customise a standard throat and hot end to work i would think. Espeically if you need to print at really high temps and the stock one is PTFE lined. Mind you a thin piece of steel tube 3mm OD 2mm ID could be used to replace the PTFE

Yo tengo dos impresoras de las normas y paraba de comprar esta misma pieza y el calentador hasta que le coji el truco todabia me quedan un moton que tienen arreglo y si puedo las reutilizare para la Snapmaker cuando la traigan en agosto saludos.

Mi maquina Snapmaker A250 con cavina y algun extra mas mas los que pida las ay mas grandes y mas pequeñas pero ami me gusta la A250 saludos.

Please do not worry. It is normal because only if you can put the thermistor into the small hole. That will be Okay.

@Tracy, it is not ok, i had problems related to that thermistor being loose that took me days to track down (thank you @chazr33gtr for pointing it out) . and i think as customers when we express concern we deserve better than just dismissal.

@chazr33gtr,
thank you for pointing this out, i was having horrible stringing issues that turned out was a result of poor temp control. i found that putting a small amount of thermal paste into the hole helps secure the thermistor and improves temp conductivity for more accurate temperature readings with less fluctuation.

Will the thermistor drop out during the printing? Normally, it will not drop out even if it is loose.
Please check whether it is because the thermistor is too short.

@Atom @Tracy

Stable, accurate temperature readings are critical to 3d print quality and key to this is good thermal conductivity (as Atom) says from the heat block to the thermistor. Having it is semi contacting the heat block with an air gap around it and it able to move during print will lead to inaccurate temparature readings and fluctuating hot end temperatures. These need to be secured with potting compound, viscous thermal paste or such like.

I would suggest either fix at factory or at least supply some compound with future printers to allow end user to secure

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@Tracy

no the thermistor did not drop out during printing and it seems to be long enough for accurate measurement once thermal paste was applied. i agree with @chazr33gtr, that this should be done at the factory or a small amount should be included with each hot end.

thank you,

Thank you for the feedback. I surely will feedback this to the product manager and designer to improve it. Thanks again

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I would like to support this. I’d even suggest for future versions of the hotend to consider a thermistor capsule, i.e. the thermistor glued into a steel capsule. This capsule then should be fixated with a screw to the heater block.

Does the Snapmaker 2.0 have active thermal runaway protection?

And if you need more information on why we want this:
https://toms3d.org/2018/04/24/make-your-3d-printer-fireproof/
http://www.print3dforum.com/archive/index.php/t-111.html

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It has thermal runaway protection over firmware.- If you need more info you could push this forward to support@snapmaker.com

@Hauke I would be more interested in an alternative hot end. Somthing that is all metal but still fits into the original print module. I haven’t seen any drop in replacements, anyone have suggestions on where to buy or how to build a replacement?

-Atom

@Atom: To me it looks too propriatory, I think you would not find any other vendors (yet I stand to be corrected!). I suppose sooner or later someone will hack the device and publish a mount for a E3D or something. I mean with the huge build volume of the A350 a vulcano would totally make sense! I think it is not too difficult even to hack it: The firmware is kind of open source, so communications should be reverse engineerable with acceptable effort, and as I learned they use STM MCUs, which I guess means it is serial communication with a CAN bus level shifter, i.e. any MCU of your liking would work. I think its more a matter of diligence rather than complexity, so at some point it will happen.
I suppose I will not be the one, unless the Snapmaker hotend lets me down at some point.

I think I rather will test it at some point by deliberatly pulling out the thermistor…

@Hauke to be clear I’m only looking to replace the hot end with one that does not use a ptfe tube for a heat break. so no CAN bus communications are needed (as that is for the extruder). Though i do agree at some point someone will create a alternative extruder module. I would love to see somthing like the nimble extruder on the sm2, hopefully that would let us break the 40mm/s speed cap :wink:

I guess I was not clear enough - I think even the hotend alone is propriatary - but as I said, I may be proven wrong.

The 40 mm/s speed is in my eyes not related to the hotend. Btw., the official statement for Snapmaker 2 is 60 mm/s print and 80 mm/s travel speeds: https://support.snapmaker.com/hc/en-us/articles/360044341034-What-is-the-recommended-3D-printing-settings-in-Cura-or-Simplify3D-for-Snapmaker-2-0- (need to scroll down a bit)

If you are in the Facebook group, look for the posts by Josef Walter Hausknecht - he went up to 120 mm/s with modified linear modules.

On my “old” printer I had a crappy hotend until recently, and still have the original bowden tube feeder which I’d estimate to be on par at best with the Snapmaker feeder, and with that and a 0.4 mm nozzle I was able to do even 150 m/s on a CoreXY system, so I yet have to find the hotend the limiting factor. My guess is that if you run a large nozzle plus large layer height plus high printspeed you’ll at some point need vulcano or supervulcano or something similar.