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CW2/SB Guidler Apparent Thermal Damage


New member
Hello. My first Voron build is from a Formbot 2.4R2 350 mm kit and includes some mods (pins, SB/CW2, two-piece PCB, chamber thermistor, KlickyNG, SexBolt z-endstop, automatic z-offset calibration, KlipperScreen, nozzle scrubber, Nevermore Micro V5 Duo XL, Smart Filament Sensor, snap latches, lighting, camera).

If it makes any difference, I am printing Atomic Filament ABS.

A thorough tuning with Ellis' Print Tuning Guide and input shaping have been performed and excellent, fast prints are routine.

With the fully enclosed build chamber and no exhaust (Nevermore recirculation, instead), I am running with a chamber temperature between 50 and 65 °C, depending on print duration and ambient temperature. After about 20 hours of print time (cumulative), I start to get significant skipping with the extruder (under-extrusion). The good thing is that this is completely solvable by replacing the guidler (I have not narrowed it down to which of the two parts, but probably the one that actually interfaces with the pivot screw and the shaft that the gear rides on). After I replace it, the prints will go back to perfect quality for another ~20 hours. I suspect that it's heating up too much in the CW2 mechanism, probably to about the glass transition point of the ABS that the part is made out of.

Have you experienced anything similar, or heard of this issue? I haven't been able to find anyone having quite the same problem.

It is possible that the two-piece PCB may obstruct a little bit of airflow in the toolhead. It is possible that the 4010 hotend fan that Formbot supplied is not sufficient. Another potential solution would be to replace the guidler with one made out of something with a higher glass transition point, such as ASA, PC, or aluminum (haha). I haven't found anyone selling CNCed CW2 parts, though I did find an entire Al CW1 on AliExpress. My concern would be that there could still be damage to other parts if the temps in the extruder are high enough (90+ °C?) to cause damage to the guidler, so improving cooling may be a better solution.

Your input would be appreciated, as it seems like this is the only current hurdle for me with this unit. Otherwise, I am very impressed with the engineering.


Well-known member
You may have already checked, but is the hotend fan set to the correct voltage on the control board?

Which hotend are you using? I have had bushing bearing fans slowly loose rpm. I replace with dual ball bearing fans. They last a long time and maintain their rpm.


New member
Heh, yes, but a good question. 24 V fan with 24 V set on the board.
But... it doesn't seem like there is much of a path for airflow up into the CW2 mechanism. I am using the Phaetus Dragon HF hotend.
I am planning on replacing the fan with a Sunon 4010 MagLev, unless that's a bad idea for some reason.
Thanks for the thoughts.

Some more information: I am measuring the aforementioned "chamber temps" with a probe maybe 2 cm above the extruder motor. Heat-soaked and about 30 minutes after a 2-hour print, with the bed heater and extruder still at print temperatures, chamber reading 55 °C, the guidler sits at 70 °C and the extruder motor 75 °C. So, probably a little hotter when running... right into the softening range of ABS...