Re: Ramps 1.4 24v part cooling fan minimum start speed in Marlin

Quote
v1talogy
If that is the case, what happens if you manually give them a 'nudge', just to help them get going... do they continue to spin afterwards?

Yes given a little nudge they do start to spin just fine, seems like at 24v (and 24v volt fans) do require more initial power to get them spinning.

Quote
Dust
most likely this is just the fans... your previous example is an anomaly

Some have had luck adding a small capacitor across the back of fans to make them play nice with PWM.

Actually I have both Taz 5/6, Lulzbot definitely went through a few different cheaper/inferior fans before switching to Pelonis fans on the Taz 6 that are much more expensive, and yes they do have the lowest starting PWM compared to past fans. I've also built many different print heads for my Taz 5/6 (Volcano, etc) and have used many different 12/24v fans, 12v with diode definitely have lower starting PWM than the 24v fans.

My Taz 6 had always had full linear PWM fan range where as my Taz 5 didn't, and I've always just assumed the difference was in the nicer fans, but the same print head/fans on the same Taz 5 now with "latest updated" Marlin 1.1.5 does have full PWM range.

I'm experimenting different range of parts on this test printer I'm building to gain knowledge/experience for my future builds, and they most likely will all be 24v, so I would like to figure out how Lulzbot did it.

Thanks for the replies.

EDIT:
My account just got approved at code.alephobjects.com and I took a look at their Configuration.h and see that they are using #define FAST_PWM_FAN:

// Increase the FAN PWM frequency. Removes the PWM noise but increases heating in the FET/Arduino
#if defined(LULZBOT_FAST_PWM_FAN)
#define FAST_PWM_FAN
#endif

and under Conditionals_LulzBot.h

/****************************** FAN CONFIGURATION ******************************/
 
 // For the Pelonis C4010L24BPLB1b-7 fan, we need a relative low
 // PWM frequency of about 122Hz in order for the fan to turn.
 // By default, FAST_PWM_FAN appears to PWM at ~31kHz, but if we
 // set a prescale of 4, it divides this by 256 to get us down to
 // the frequency we need.
 
 #define LULZBOT_FAST_PWM_FAN
 #define LULZBOT_FAST_PWM_SCALE                    4
 
 #define LULZBOT_FAN_KICKSTART_TIME              100
 #define LULZBOT_FAN_MIN_PWM                      70
 
 #define LULZBOT_USE_CONTROLLER_FAN
 #if defined(LULZBOT_IS_MINI)
     // The Mini fan runs rather loud at full speed.
     #define LULZBOT_CONTROLLERFAN_SPEED         120
-#else
+#elif defined(LULZBOT_IS_TAZ)
     #define LULZBOT_CONTROLLERFAN_SPEED         255
 #endif
 
 // As of Marlin 1.1.5, FAST_PWM_FAN adjusts the frequencies for
 // all fans except the controller fan. This workaround allows
 // the controller fan PWM freq to be adjusted to 122Hz (this
 // may not be necessary, but since the Pelonis fan likes 122Hz,
 // we are trying to keep all the fan frequencies at that).
 #define LULZBOT_FAST_PWM_CONTROLLER_FAN_WORKAROUND

I'm not very familiar with programing and have basic understanding of #define, how would I go about implementing this into my own Marlin?

Thanks again.