Print cooling fan behaving oddly

[kharrisma]

On to the next issue, seems like! 

I've straightened up a number of config issues in both printer.cfg and nitehawk-sb.cfg, and the system starts with no errors.  The hot end fan spins up as it should very shortly after the heater is on, and runs for a period afterward until parameters are met.  What I can't seem to get running is the part cooling fan; using the Dashboard slider, it *will* spin up, but only at 49%, (no spin at all at anything less than 49%) and then it spins at about 20% (ballpark guess), and stays at that same speed (again, a guesstimate using a worn-out Mk I eyeball), until the slider reaches 100%, then it takes off like a gas-powered leaf-blower.  RPM's measure zero, until 100%, then I get a reading that fluctuates around 9880 RPM (specs say it's rated at 7200 plus/minus 10%.)  I get the same response using gcode commands directly: m106 s(0 to 255)... no spin until s129, same spin rate until s254, then s255 where it takes off at warp speed again.

Triple-checked the wiring, which is correct according to the information on Fabreeko where I bought it (HoneyBear 5015, four-wire with PWM and Tach).  It IS a 24-volt fan, and spins up fine with 24 volts directly applied to the plus/minus leads. 

Here's the config entries for the fan:

## Print Cooling
[fan]
pin: nhk:gpio6
max_power: 1.0hnhk
shutdown_speed: 0
cycle_time: 0.010
hardware_pwm: false
kick_start_time: 0.100
off_below: 0.0
tachometer_pin: nhk:gpio17
tachometer_ppr: 2
tachometer_poll_interval: 0.0015

Doesn't look any different than the hot end fan config entries, save for the naming and the nhk pin callouts.

Attaching both printer and nitehawk config files for 'full disclosure.' 

Any suggestions are much appreciated.  Boy, can't wait to get into the "barf" LED effects.... that should be a trip!

nitehawk-sb.cfg printer.cfg

[RopusLongus]

Depending on the Manufacturer it may needs another kick off.

I use rep rap but with sunon fans I need to use a different setup then with a fan from other manufacturers.

Can't translate it into Klipper but I guess the hrz rate needs to be lower.

[RopusLongus]

Just a guess but maybe hardware pwm needs to be activated?

[kharrisma]

Stumbled across an answer of sorts on the Fabreeko discord.  Apparently quite a few people have issues with the Nitehawk and this fan. (4-wire version.)  One guy sets his his with "hardware_pwm: true", and "cycle_time: 00004 # 24kHz".  Tried those settings, and it runs much better; still a bit rpm heavy at the low end; 2% is as low as it goes, and it's making noise at that (not the quietest fan going....)  It's not ideal, but it's useable at this point.  I can fine-tune it as I go - - at least I can print with it now!