When is the fan supposed to start?
Hi. I started an print with minimum fan speed of 10% after first three layers, but fan never started.
I went into live tune menu and the fan was at 25, did give the fan an manual flick with my hands and it started.
I tried on another print with zero fan to slowly increase fan speed in live tune menu, it seems like it didn't start before between 25-30, is this normal?
Re: When is the fan supposed to start?
This doesn't really work 100% securely.
The fan is only powered wirh supply voltage, no PWM. So the fan has an relativ high starting point. My fan starts securely at about 35 (LCD-Menue) or at 15% (in slicer-programs).
A better way is to use an PWM controlled fan, but this is not supported by the Rambo. But it's relativ easy to modify. You should have experience in soldering SMD or very thin wires !
Thomas
Re: When is the fan supposed to start?
Thanks, that's what I expected. Just wanted be be sure.
Wierd that default minimum value of colorfabb HT is 10% in slic3r.
Shouldn't the settings be tuned, or an feature in firmware that always bumped fan to 35 points before going down to setpoint.
Re: When is the fan supposed to start?
this behaviour of the print fan is quite common. other printers suffer the same problem.
that's why some slicer programms have an option to set the fan for a short time to "full power", so that it starts properly.
but you have to enable this behaviour first.
in simplify3d you can find the option at the <Cooling> tab, it's a checkbox labled with "Blip fan to full power when increasing from idle".
dem inscheniör is' nix zu schwör...
Re: When is the fan supposed to start?
10% is similar to 25 (on LCD). This is not enough to keep the fan running, it will stop.
For my printer 15% (35 LCD) are save values. OK, this is the second reason why I upgrade to an PWM powered fan with auto-restart 😉
But be carefull, fan will not start at 15%, starting value is more, for my printer 20%.
Thomas
Re: When is the fan supposed to start?
Yeah, did some experimenting, mine seems to start fine at 15%.
But tried searching google for pwm controlled fan for prusa, but I could not find any guide or simular.
Do you know of some that shows what is necessary to add pwm controlled fan? I do have experience with soldering.
Re: When is the fan supposed to start?
You find some information in the thread here : http://shop.prusa3d.com/forum/improvements-f14/alternative-nozzle-cooling-t4395.html
Just waiting for my rods, then I will implement and test the new extruder, and test the fan too. Please be patient.
But if you are familiar with electronics, the theory is to add to additional parts in the Rambo, a diode and an elco, make an 3rd wire to the fan (for the PWM).
You have to add the elko (470µF should work) parallel to the power-supply of the fan. The 3rd wire (PWM) goes via the diode (1N4148 or equivalent) to the junction R9/R16 on the Rambo PCB. Cathode on R9/R16, anode to the fan.
Thomas
Re: When is the fan supposed to start?
Update : http://shop.prusa3d.com/forum/improvements-f14/alternative-nozzle-cooling-t4395-s30.html#p36090
You don't need any additional eletrronic parts, except a 3rd wire and some sockets & plugs.
Thomas
Re: When is the fan supposed to start?
Having the same issue. It only gets connection when the extruder is on the front/right of the bed. I've emailed tech support to see if they've developed a fix.