Fan installation (Page 3 of 5)

I'm a little iffy on this as well. Perhaps you should ask Eric Zalm.

I had that same issue using that design. I had to beef up the insulation around the hot end. Perhaps another wrap or to of fiberglass mat and some kapton.

Guys, i've read through this post but still need a bit more help... I want to connect a fan to my normal sanguinolou board. How do I go about the wiring to control it through gcode? I have very little experience of gcode, but fine with a soldiering iron!

I need to know which terminals I connect to and is it possible to control the fan speed through software?

Cheers

Throw a MOSFET on that pin. Ian details it in his blog:

http://solidoodletips.wordpress.com/201 … ruder-fan/

Elmoret, that's what I thought too (that the MOSFET would "translate" 5V PWM to 12V PWM), but I tried something similar (this: http://www.thingiverse.com/thing:22202, which I believe is what Ian started with) and it's either fully on (even with low, but non-zero control signal) or fully off, no in-between.  However, I do hear a slight whine from fan when PWM is <255 (so some switching must be going on), but a voltmeter says either 0 or 12V.  I believe I read somewhere that Ian had similar issues? I'm investigating (although semiconductors are not my strong suit, to put it mildly), if I make any progress, I'll post.  Did you manage to get it to work?

This is normal for PWM, especially cheap multimeters.

Don't motor speed controllers pulse at full voltage and the speed controlled by the number of pulses? I don't know if this is true for these type of fans?

Wish i knew more about this stuff!

P.s. what does pwm stand for?

Ok cheers... My multimeter does sign waves i think i've never used it to do much, should be interesting to see if i can monitor the mudulation.

Thanks -- I suspected this, so I checked what my meter said for pin 4 (D12), and it gave the expected results (5*pwm/255 Volts). Unfortunately a multimeter is all I have.  Does it matter if there is a load on the MOSFET output or not (I measured both D12 and MOSFET with just multimeter connected)?  Could it be the capacitor (too large)?  Or something to do with PWM frequency perhaps? I'm mostly trying things blindly, I admit.

Also, the fan speed seems to depend on history -- i.e., if I go from S5 to S60 in +5 steps, the fan doesn't move up until ~S50. But going in -5 steps from S60 to S0, the fan only stops moving around S5. Is this also normal?  Or something wrong with the fan?  (BTW, at ~S10 I can see by eye that the fan rotating slower -- unfortunately, the flow is not enough to judge airspeed by hand or even by hanging a piece of, say, string in front of the fan). 

The main reason I care about PWM is not so much the plastic, as that I would like to turn it on gradually, since nozzle temp drops by up to 25C if I turn it on at once -- I was hoping that PWM might help with that.

Thanks everyone for all the hints!

I tried the fan installation today following Ian Johnson's write up on solidoodle tips.wordpress.com.  It was very well written which was good for me since I am a complete novice.  The net result was that the fan is on 100% of the time. I could not shut it off from the manual control screen in Repetier. Nor could I set it to turn on or off with Slicr settings.  Are you guys manually inserting M160 commands in the Gcode after slicing to get the fan to turn on or off or would you say I have a problem with my mod somewhere?

I noticed that the MOSFET I ordered did not have the same number as the one displayed on Ian's blog, so I'm tempted to try and find that exact one and try again, but it seems like along shot. I did update the pin settings in the Marlin_SD3.pde file to #4 from the default -1 however, in an attempt to trouble shoot I switched the pin setting back to -1.  The fan still turned on and ran 100% of the time with define pin set at -1.  At any rate I suppose it is all part of the learning curve, but any tips or suggestions would be much appreciated..........

I suppose I could have mixed up the ground and the gate (right and left side connections on the MOSFET). Would you say this could cause the fan to run 100% of the time?  Luckily I used some extra wire for the MOSFET connection and should be able to get to it relatively easily without pulling the circuit board off again. Running a print now but will try transposing the left and right leads soon. Thanks

Thanks Lawsy.  I very much appreciate the help.  In this case it turns out I made a bit of a boneheaded move and updated the wrong section of the pin.h file. After reviewing with more care, I found the SD section within the pin.h file and changed the fan pin from -1 to 4.  The fan is working well now (turns off,on, variable speed, Gcode controlled etc).  I'm surprised the fan came on at all with the wrong pin setting, but perhaps with this MOSFET the gate is open until a signal is received.  Thanks again for the tips. 
Frank