by RetireeJay » 2019-Mar-Fri-14-Mar
That's not the right way to connect the fans.
If you hot end requires a fan, then the fan must be on at 100% speed whenever the hot end is above 55C. With a Printrboard, that generally means the hot end cooling fan will be on 100% of the time because the Printrboard doesn't have a separate driving circuit for the hot end fan. Instead, you wire your hot end fan directly to a source of +12V. If you have an ATX power supply, that's easy and the Printrboard is not involved.
The print-cooling fan, on the other hand, can be off some of the time and turned on at various percentages depending on the material you are printing and the type of printing you are doing. Small-area layers (like the smokestack on Benchy) pretty much require cooling, and bridges also benefit from cooling.
So the two functions are truly independent of each other; the needs are unrelated and hooking both fans up to the same (controlled) output on the Printrboard is not recommended.
If you find that you don't need a print-cooling fan ever, then you could use the Printrboard's controlled fan output to run the hot end fan; just be sure it's on 100% whenever the hot end is in use.
Or, you could have your print-cooling fan AND the hot end fan on at 100% all the time. It's noisy, and the print-cooling fan might actually degrade your print quality in some circumstances. You'll have to monkey around with settings in your slicer to make sure the fans never get turned off.
Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S