Unresolved Temp Falls After Fans Turn On

Hey folks,

Have a little bit of trouble maintaining temperature on my hot end after the cooling fans kick in. Here's my config:

Hardware:

• E3D v6 Hot End
• Screw-in Stud Thermistor (from Printed Solid)
• Novice Expert's Tooless Fan Ducts
• 2 x 40x10mm fans
• PLA

Software:

• Cura 15.04
• 200c Print Temp
• Cooling Fans Enabled
  • "Fan full on at" 1.6mm
• Max Fan Speed = 60%
• Min Fan Speed = 60%

Here's a picture of my temp graph. It's odd, because it starts to recover, but seems like the heater block doesn't stay on long enough. You'll see it hovers pretty consistently, but is 8-10 degrees too cold.

What do you think? Could the fans be cooling off the heater block that much? Why won't the heater stay on until it's fully recovered?

I don't think it's the thermistor because it's fully encased in a brass threaded stud with an epoxy on top.

 

Actually, I may have answered my own question just now...

I put a paper clip to stop the one fan from turning that's closes to the side with the thermistor and heater block. Wouldn't you know my temp went right back up.

I wonder if turning the heater block 90 degrees will solve that problem, moving the thermistor away from direct cooling... Any suggestions?

 

Moving the thermistor away from the fan will absolutely help the issue

 

I created a Y adapter so that I could just unplug one fan or the other in moments like this. Just glad it wasn't your finger Also, I've heard from others on this site that using a fan shroud with a 10mm fan is not as affective as a 20mm fan for getting the volume to push the air. I haven't tried either with a shroud, so I can't say for sure, but worth mentioning just in case you wanted to upgrade in the future.

Sounds like you fix will work though.