Insufficient Part Cooling - [Solved]


#1

I’ve been noticing a lot of overheating issues on my parts and I suspect that the fan is not getting enough power.

I have tested hotend temps from 170-210, all with similar results so I am pretty sure the issue is not caused by an excessively high printing temp. Granted, I am using a cheap PLA that I have had to bake to get rid of moisture, but I still don’t think the issue is with the filament, because it has worked for me before.

I tried using Marty’s alternate fan duct (found on wilson github), but there was barely any airflow coming out. To see if my fan was burnt out, I ordered two other fans with similar electrical specifications. When plugged in to the FET4 connection on the PICA board, they both made noise, but neither spun. I ordered two blower fans, you can see them here and here.

Because none of the fans that I’ve tried have worked, I suspect that my PICA board is not outputting enough power to my fan. I could be totally wrong about this conclusion, so I wanted to see what everyone else thought?

I am looking for suggestions on how to get my fan working again. Should I try another fan duct? Am I buying bad blower fans? Should I crimp on different connectors to my fan and plug it into another connection?

Thanks!
Nick


#2

That looks very much like over extrusion to me: https://www.google.com.au/search?q=overextrusion&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwivxaKFj7rUAhVKHpQKHQQODAcQsAQILg&biw=2135&bih=1030

Have yo calibrated your e-steps?

Granted I don’t run the stock fan, but I found it to be ok, certainly nothing that would lead to that.


#3

That’s a good thought, it has been awhile since I re-calibrated my extruder steps. My main issue is that the top layers of my print (especially corners or overhangs) will curl upwards during printing and sometimes get in the way of my nozzle. Does this sound like over-extrusion? To be clear, only the top layers are curling upwards as shown below, this is not a thermal warping issue where the part detaches from the print bed.

One of the main reasons I thought it was due to insufficient was this article on curling and rough corners. The picture shown above is very similar to what I am experiencing with corners and overhangs.

However, I have still have one big issue. I would really like to switch to a blower style and make a fan duct similar to the Prusa i3 MK2 (like this one), but the only fan I have that works in the FET4 power connection is the stock fan. Is it possible that my board is simply not supplying enough current or voltage through this connection anymore? Or do I need to buy fans with different source voltage’s and impedance’s?


#4

Keep in mind I’m a relative newb, so take any advice I give with a grain of salt.

I am running ramps (although a pica upgrade might be on the cards in the future) so I can’t comment on it, but I doubt that it would be insufficient to run a fan unless it was defective. You could try connecting the fan straight to 12 v and see if there is a difference You could also do a crude displacement test but directing the fan into a garbage bag and timing how long until it fills - I’d only use this method for comparative measurements (ie FET vs 12v direct) as it would be far too inaccurate for a decent measurement.

I am certainly no fan of the stock duct, I had heaps or problems with it, but I’m not sure that was an issue with the duct or the user. I am currently using the magnetic mounted duct found here: https://www.thingiverse.com/thing:2068291 the pro is that being magnetic you can remove to observe the first layer going down.

I am currently in the process (ie waiting for all parts to come in) of upgrading to a titan setup, and with that I plan to use a prusa style blower setup:https://www.thingiverse.com/thing:1746358

However I just saw this: https://www.thingiverse.com/thing:1771184 while looking for the link above, and it is intriguing.


#5

If you’re not sure if the problem is enough air flow from the print fan, a good way to tell is just put a desk fan next to the printer and point it at the print area. For PLA, air flow is good and as long as it’s not so much that the bed can’t stay warm then more is better. If your prints suddenly look great then you know it is indeed the print fan.

I agree also that it looks like over extrusion (too much plastic per area). What are your esteps/mm set to?


#6

I’ll make sure to try your desk fan suggestion and let you know what I find. But my Esteps/mm are 100.8, does that sound too high?


#7

Did you figure out what the problem was? I’m having a similar issue now. I calibrated my my extruder and my Esteps/mm are 101 so it’s close, but with my previous board I had to turn it all the way down to 55 to get it to print correctly, it might’ve been a bad board. I still get what appears to be over extrusion with a calibrated nozzle.


#8

So turns out that the PICA board does supply enough power (Sorry for overreacting). When I was testing fans, I would unplug the stock fan and plug in the replacement fan without turning off the machine. This seemed to cause some issues with the software and I couldn’t get the fan to run. When I turned off my printer and changed fans, I could get the fan to properly run at full power.

As for the actual issue, It does appear to an overheating issue. My stock fan was pretty weak and the air duct was aimed behind the nozzle and was not properly cooling the parts. I bought a blower fan and made a fan duct similar to the prusa i3 mk2. I’ll post a picture of it and the part files when I test the design a little more.