Struggeling with PLA - Nozzle temperature off?

Hi Snapmakers,

I have a new brand of PLA, which behaves unwieldy. So I decided to run a temperature tower to understand at which temperature to print with best. Turns out: None!
Fired up my other printer, started a temp tower with the same PLA spool - what a difference! The printer knocked the tower off the bed half-way, so part is missing, but from the photo below the difference is quite eminent!
So I asked myself: What can it be? Two options came to my mind:

  • print cooling broken
  • Temperature of the nozzle not right

Print cooling is fine, checked with M106, and I assess the intensity to be enough, my old printer is cooling at comparable intensity (difficult to judge objectively however…).
So remains nozzle temp. I unmounted the hotend from the toolhead and looked at the thermistor: It is not put into the hotend with thermal paste! So the contact to the heater block is poor (a round shape in a cylindrical hole…), and I’d think it likely that the nozzle temp is much higher than the thermistor thinks it is!

Anyone having similar experience and perhaps a thermometer capable of checkingthe nozzle temp?

I will get myself some suitable heat paste and see if this changes things…

Here’s the picture:

It’s known that the thermistor is not properly secured and conductive ( frex, )—it seems that the Snapmaker people just didn’t realize it was useful to smear in some thermal paste.

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Yeah, but I was of the false impression that only the replacement hotends had this flaw… Stupid me.

OK, what a difference! Topmost print (most backward): SM2 at 210°C (not 100% sure but 200+). Second/mid: SM2 at 190°. Front/lowest: Fabtotum at 195°C. SM2 at 0.08mm layer, 80 mm/s, Fabtotum at 0.1mm layer 80 mm/s. Looking at it is clearly overheated/curling at corners. I’d put a bet on nozzle temp too high! OK, will not be able to test in the next three weeks, but then I’ll get myself thermal paste and report here.

(For those that want to test themselves: Its the seal from this nice thing:

Seems @Atom was faster and had success (only now stumbled across his post): Improving Print Quality Seems to be a point in favour of my theory…

Definitely thermal paste is a must for good printing with the SM2. Sorry I didn’t see your post sooner or I would have chimed in, there have been several posts pointing to poor hot end temp control.

Hi folks,

I now applied thermal paste to the thermistor, and obviously I was completely wrong: There is no change, the temp tower printed with the paste applied is exactly as bad as the one before. I decided to change the hotend completely for a test, since I suspected the thermistor to be defective/out of tolerance, but even with the replacement hotend the temp tower is crappy like hell. So I am at a loss: Why do I get such bad results? My last idea is print cooling fan. If I compare the airflow I can feel with my fingers setting colling fan to 100% on my old printer to the Snapmaker, my old printer might be a bit more powerful, but it is difficult to tell just by feel.
What I will do now is print the temp tower on my old printer with fan speed set to - dunno - 20% or so and see if the results turn as bad.

In the meanwhile: Anyone with helpful insights?



I found bridging to be particularly challenging for these devices, and I have a 7" desk fan next to the printer I turn on after the first layer finishes. Besides preventing the bed from ever getting over 62C and possibly reducing layer adhesion I haven’t seen any negative effects.

I have also fought some slicer’s bridging gcode generation - I love Simplify3D, but I think Cura generates better bridges when the Advanced Bridging options are enabled.

Also, check out this for other things I went through to optimize the prints:

My new blowers showed up today, this weekend I’m planning on increasing the part cooling, the built in part cooling fan is comically underpowered.

The funny thing: My very first serious prints with SM2 were with considerable bridging, and I was/am rather pleased. However, that was with a different PLA brand. And it’s this green PLA that gives me headaches, other PLA workes much better, but not perfect,
Thanks for pointing me at the summary artice, it saves me the effort of pulling this together myself. I suppose I need to play with accelleration/jerk and all this stuff, because I just ran the temp tower with my old printer at 20% fan speed, and while the result is somewhat worse than with 100% fan, it’s still much better than what Snapmaker makes of it. However, I noticed that my old printer goes slower in some places, which I assume is exactly because of different calibration settings for accell, jerk etc. So I’ll do the calibration as suggested with the artice.
E-steps/Extruder calibration was basically the first thing after my first prints, because I had heavy underextrusion, and retraction I also have now tackled, which also caused underextrusion before.

Next thing I’ll do is run the temp tower on SM2 with 50% speed setting - see what this will bring.

And please keep us posted on the fan - do you replace the stock cooling fan, or do you add a fan externally?

So the original fan is a 2510 axial tiny tiny thing. Here’s all the fans: FYI: Snapmaker 2 & Enclosure Fan Information plus alternatives

So I bought a 5015 radial blower with the same connector on the end (on amazon) and plan on disconnecting the built in one, connecting this one, and designing and printing a clip on bracket. If the bracket doesn’t work, then double sided tape. But that blower is going on one way or another.

Will let you know if it works :stuck_out_tongue:

Currently running the SM2 print at half speed, and looks better already. However, I may still have an extrusion issue! I can watch how the printer lays down the first bridge, and it is perfectly straight and nice, and while it adds layers above, the bridge gets pressed down - which may indicate overextrusion. So I think I need to revisit extruder calibration… sigh

Part cooling mod

There is a clip in development. Be careful not to pull to much current with the new fan or you will burn up your print head.

@atom Thanks for the reminder about that thread - I forgot about it. I think I’ll give it a shot regardless, I can use the modelling practice.

Any chance you know any numbers that would help me figure out what’s too much? I have thought about this:
Old 2510: 0.05A, 2.95CFM (from XYJ24B2510H)
New 5015: 0.15A, 6.5CFM

I’m figuring bumping the 1.2W fan up to 3.6W is pretty safe, considering the hot end heater cartridges are usually 40-50W. I’m hoping their design was not so tight the extra 2.4W puts it over the edge.

The issue isn’t the overall power, I’m sure the cable can handle alot more. But its the transistor and leads in the circuit board that power the fan as compared to the ones that power the hot end (For example look at the size of the wires that lead to the heat block and compare them to the wires that lead to that cooling fan). And trippling the current draw is substantial. Most systems are designed for no more than %150. And even that usually causes excessive wear. Interesting that you say the original fan pulls .05A when I think @Franky said it pulls .1A

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You make a fair point, I’ll try and dig up the data sheet for the amplifier they use if there’s not a heatsink glued to it. In my experience even a tiny tiny transistor can carry 200mA without a heatsink pretty well, but I haven’t done very much small power designs recently.

As far as PCB traces and wire size - the heater cartridge will draw around 2A, which can be carried by #24 wire, extremely tiny, only .5mm. The size of the wires is because it uses a high temp silicone shielding, not because of the ohmic losses from the current draw. And same with the PCB traces, even a 3.5mil trace could carry the required fan mA.

Yes most threw hole transistors can handle .2A however it would not surprise me if they used a small surface mount transistor if they only intended for it to run .05A and many of those will not run .2A and they are almost impossible to put heat sinks on. But please do let me know what you find out!

Yea clearly I’ve only worked with through holes. Will update this with an answer in like an hour. Sure hope I don’t have to run an external power supply for this thing - it’ll ruin the beautiful aesthetic of the CAN cabling

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If the built in transistor won’t handle the power you can always add an extra transistor powered directly from the 24v input on the board and have it controlled by the existing transistor. That should be small enough to fit inside the original print head casing to keep that stock look.

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The transistors are marked 0102 so I’m guessing an NCE0102. 2A rated.

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Hi @brent113, first of all, welcome to the forum :smiley:

@Atom is right, here you can see the picture of the hotend fan:

and it’s rated to 0.1A.

The reason to try to achieve that 0.1A is to ensure the circuitry and the control supports it. As you surely know, it’s not only that the transistor is able to handle the current, is also that the overall circuitry is able to manage and control it ( as we don’t have the schematics we don’t know how they are trying to control it, we can just guess and try) . But in your case, you can easily hook the new fan (maybe with a small control pot or similar to be able to directly control the current ) and see if the current can be achieved. If you don’t ensure you can generate enough current through the fan, the expected benefit will not be achieved :wink:

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