Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle I have been having this issue for months now. However, only yesterday did I notice where the issue is coming from. When I print with Nylon230 the print randomly stops. I checked the extruder motor. Extruder voltage etc. However, I shined a flashlight on the Hotened Fan that is always on. I could see the fan spin and then turn off during a print. Then immediately turn back on. This occured for every layer. The fan would go full blast, then slow down to off for the next layer, it would turn on again, then for the next layer slow down to off but immediately turn back on to finish the layer of the print. Randomly the nozzle would get clogged at different z heights. I assume because the heatbreak got too hot. Is this a known issue? Is there a cure? I have attached a second larger fan to the hotened but it has the same issue of turning off but then immediately back on. It doesnt help with the prints much. https://reprap.org/forum/read.php?416,776740,776740#msg-776740 Sat, 12 Sep 2026 21:54:42 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?416,776740,776944#msg-776944 Re: Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776944#msg-776944
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dc42
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o_lampe
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The fans are connected to EO and E1 on the Duet Ethernet board.

I don't have my DuetWifi at hand, so I can't check....but it sounds like you powered the fans through the Extruder ports? Or are there fan ports called E0, E1?
Forgive me if I'm wrong, just shooting from the hip.

I agree, that's what it sounds like. The hot end fan should be connected either to one of the always on fan connectors, or to the Fan1 connector and Fan1 left in thermostatic mode - or you could connect it to the Fan 2 output if you are using Fan 1 for something else and configure Fan 2 in thermostatic mode.

Checked the cabling. The hotend fan is connected to FAN1 and I set it to always on. The 2nd Hotend fan is connected to FAN0 and I have that set to be able to be used by the Fan Slider in the PanelDue and Web interface.

Always on Fans are connected to a Fan that cools the Extruder motor on the Kossel. The 2nd Always on Fan is set to cool the CPU on the Duet Ethernet. Because of my Arduino I am afraid of frying my CPU.

DC42 thanks for the advice. I will connect the main hotend fan to always on connection. Leave the 2nd hotend fan to Fan0 so I can control it as I need. I will then swap the CPU cooling fan to the Fan1 location as it is set to always on but not that important (I have it because of my fear of frying another Duet board).

Update: Rewiring of fans complete. It works perfectly. Thanks for the help DC42. My clogged nozzle issue with odd fan behavior is fixed.]]> DRTak Duet Fri, 07 Jul 2017 11:36:23 -0400 https://reprap.org/forum/read.php?416,776740,776894#msg-776894 Re: Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776894#msg-776894
Quote
o_lampe
Quote

The fans are connected to EO and E1 on the Duet Ethernet board.

I don't have my DuetWifi at hand, so I can't check....but it sounds like you powered the fans through the Extruder ports? Or are there fan ports called E0, E1?
Forgive me if I'm wrong, just shooting from the hip.

I agree, that's what it sounds like. The hot end fan should be connected either to one of the always on fan connectors, or to the Fan1 connector and Fan1 left in thermostatic mode - or you could connect it to the Fan 2 output if you are using Fan 1 for something else and configure Fan 2 in thermostatic mode.]]> dc42 Duet Fri, 07 Jul 2017 05:47:31 -0400 https://reprap.org/forum/read.php?416,776740,776862#msg-776862 Re: Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776862#msg-776862
Quote

The fans are connected to EO and E1 on the Duet Ethernet board.

I don't have my DuetWifi at hand, so I can't check....but it sounds like you powered the fans through the Extruder ports? Or are there fan ports called E0, E1?
Forgive me if I'm wrong, just shooting from the hip.]]> o_lampe Duet Fri, 07 Jul 2017 01:50:28 -0400 https://reprap.org/forum/read.php?416,776740,776845#msg-776845 Re: Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776845#msg-776845
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dc42
Which fan output do you have the hot end fan connected to, and how have you configured it in config.g? Are you sure that the cabling is sound?

I will double check the cabling. But I have added another fan to the heatsink part of the hotend. The fans are connected to EO and E1 on the Duet Ethernet board. Both intermittenly stop and go during a print. But by adding the 2nd fan I can now fully complete a test print of a temperature check tower that I found on thingiverse. However it doesnt make sense that new fan is stop and go as well. Example: the calibration tower is square that I am printing. Every revolution of the hotend the fans slow down or stop, then pick back up during the next layer. It is only noticeable if I shine a flash light into the fan itself.

Here is my config.g file:
; Configuration file for testing Duet Ethernet and Wifi

; Communication and general
M111 S0 ; Debug off
M550 PDuetMindy ; Machine name and Netbios name (can be anything you like) Originally DuetTest
M551 Preprap ; Machine password (used for FTP)
;*** If you have more than one Duet on your network, they must all have different MAC addresses, so change the last digits
M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address

;*** Networking - Enable for both WiFi and Ethernet boards.
M552 S1 ; Turn network on

;*** Ethernet networking: Adjust the IP address and gateway in the following 2 lines to suit your network
M552 P192.168.1.14 ; (0 = DHCP)
M554 P192.168.1.1 ; Gateway original was P192.168.1.255
M553 P255.255.255.0 ; Netmask

M555 P2 ; Set output to look like Marlin
G21 ; Work in millimetres
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves

; Disable Fan 1 thermostatic mode
M106 P1 T20 H1
; Added this myself to make extruder fan always on at 20 deg celcius
;M106 P0 T20 H1 ; I added this myself

; Axis and motor configuration
M569 P0 S1 ; Drive 0 goes forwards
M569 P1 S1 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S1 ; Drive 3 goes forwards
M569 P4 S1 ; Drive 4 goes forwards
M574 X2 Y2 Z2 S0 ; M574 X2 Y2 Z2 S1 set endstop configuration (all endstops at high end, active high)
;*** The homed height is deliberately set too high in the following - you will adjust it during calibration
M665 R108.97 L215.00 H237.62 B110.00 X0.76 Y0.60 Z0.00 ;Old M665 R108.99 L 215.00 H237.63 B110.00 X0.78 Y0.65 Z0.00
;set delta radius, diagonal rod length, printable radius and homed height
M666 X0.22 Y0.27 Z-0.48 ;Old M666 X0.21 Y 0.27 Z-.47 and original M666 X0 Y0 Z0 put your endstop adjustments here, or let auto calibration find them
M350 X16 Y16 Z16 E16:16 I1 ; Set 16x microstepping with interpolation
M92 X80 Y80 Z80 ; Set axis steps/mm
M906 X1000 Y1000 Z1000 E1200 I60 ;M906 X1000 Y1000 Z1000 E800 I60 original ; Set motor currents (mA) and increase idle current to 60%
M201 X1000 Y1000 Z1000 E1000 ; Accelerations (mm/s^2)
M203 X20000 Y20000 Z20000 E3600 ; Maximum speeds (mm/min)
M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute
;M579 X1.001 Y1.03 ; Added this myself to scale correctly

; Thermistors
M305 P0 T2100 B3435 R1000 H-10 L0 ; Original M305 P0 T100000 B3950 R4700 H30 L0 Put your own H and/or L values here to set the bed thermistor ADC correction
M305 P1 T100000 B4725 C7.06e-8 R4700 H-10 L0 ; This works: M305 P1 T100000 B4267 R4700 H-10 L0 Put your own H and/or L values here to set first nozzle thermistor ADC correction
;M305 P2 T100000 B3974 R4700 H30 L0 ; Put your own H and/or L values here to set 2nd nozzle thermistor ADC correction

; Adjustments for J-heads used as dummy heaters on test rig
M307 H0 A90.0 C700.0 D55.0 S1.00 B1 ; I added this myself
;M307 H0 A144.1 C680.4 D0.5 S1.00 B0 ; cut and paste from config-overide
M307 H1 A250.0 C140.0 D5.5 S1.00 B0 ; cut and paste from config-overide
;M307 H0 A250 C140 D5.5 B1
;M307 H1 A250 C140 D5.5 B0
M307 H2 A250 C140 D5.5 B0

; Fans
M106 P1 S255 ; Fan1 is the extruder fan by default. It is NOT disable thermostatic mode for fan 1
M106 P0 H-1 ; added this myself to disable thermostatic mode for fan0 which is the object fan

; Maximum temperature I added
M143 S295

; Tool definitions
M563 P0 D0 H1 ; Define tool 0
G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
;M563 P1 D0 H1 F1 ; tool 1 uses extruder 1,heater 1 and fan 1
;*** If you have a single-nozzle build, comment the next 2 lines
;M563 P1 D1 H2 ; Define tool 1
;G10 P1 S0 R0 ; Set tool 1 operating and standby temperatures
M92 E100:100 ; Original M92 E663:663 Set extruder steps per mm

; Z probe and compensation definition
;*** If you have a switch instead of an IR probe, change P1 to P4 in the following M558 command
M558 P1 X0 Y0 Z0 ; Z probe is an IR probe and is not used for homing any axes
G31 X0 Y0 Z1.28 P500 ; Original G31 X0 Y0 Z4.80 P500 Set the zprobe height and threshold (put your own values here)

;*** If you are using axis compensation, put the figures in the following command
M556 S78 X0 Y0 Z0 ; Axis compensation here

M208 S1 Z-1 ; set minimum Z

T0 ; select first hot end]]> DRTak Duet Thu, 06 Jul 2017 22:16:36 -0400 https://reprap.org/forum/read.php?416,776740,776773#msg-776773 Re: Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776773#msg-776773 dc42 Duet Thu, 06 Jul 2017 14:06:23 -0400 https://reprap.org/forum/read.php?416,776740,776740#msg-776740 Duet Ethernet Hotend Fan Turns Off and On during print and clogs nozzle https://reprap.org/forum/read.php?416,776740,776740#msg-776740
Is this a known issue? Is there a cure? I have attached a second larger fan to the hotened but it has the same issue of turning off but then immediately back on. It doesnt help with the prints much.]]> DRTak Duet Thu, 06 Jul 2017 11:34:51 -0400