Fan & fan duct upgrades, hot end square fan upgrade  

Try improved fan ducts first

You might experiment with different ducts before making too many hardware mods. I found a slightly modified version of the stock fan improves cooling results. My testing on my Prusa Mk3 with the original (R2) duct didn't yield as much improvement as on my cheap Artillery Sidewinder X1. Don't expect huge improvements.

RE: Fan & fan duct upgrades, hot end square fan upgrade

Posted by: @michaelw-2

I've found fans with way more power than stock in 24V variants and I was thinking of just hooking them (indrectly) up.  The power would not come from the einsy board but the main power supply.  The einsy would simply control a mosfet type thing to prevent 24v exposure.  

Same with the hot end fan. I can find a fan that flows so much more.  

 

But is all the extra flow worth it?

I would have to optimize the fan duct to prevent hitting the nozzle directly (I think)

use a heat sock

can't think of any negatices for the hot end fan (the square one).  Can you think of any negatives?

Yes, there are some negatives, especially for the hotend fan, the square one.

Prusa Mk3 series monitors the speed of both fans.  If the Hotend fan speed is not detected very soon after the fan is activated, the printer will shut down.

The part cooling fan is also speed monitored.    Both fans are 3-wire speed sensed 5v fans.  To bypass the speed monitoring will require firmware mods.

You can get much more powerful 5v  3-wire fans, but it is not necessary.... all they will do is make a lot more noise with no benefit unless you've set up the printer in a heated chamber or are trying for max speed on PLA? 

RE: Fan & fan duct upgrades, hot end square fan upgrade

First: You do not need external Mosfets. All Mosfets on 3d printer boards do switch the GND, not Vcc.

So you can connect the ground wire of a 24v Fan directly to the ground Pin of the fan socket of the Board and the Vcc wire directly to 24V.

The problem is Tacho wire. The input on the Board is 5V. >5.5V would destroy electronics. So you have to adapt voltage of the signal. A simple voltage devider containing of two resistors and connection to a (permanent!) ground should do.

In normal operation, Firmware just checks if there is a tacho signal (so fan is spinning, not beeing blocked or disconnected). It does not check if RPM is what it should be. So if you have the fan you dream about every night, but do not have a Tacho-Line, you could even use an NE555 as oszillator to generate a fake tacho signal to avoid modyfing the firmware.