After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan
 
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After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan  

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thebrucecrowder
(@thebrucecrowder)
Active Member
After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan

I've been having thermal runaway (nozzle) problems since upgrading from MK2 to 2.5s. As seems to be a typical problem, the nozzle temp drops considerably when the fan kicks in. It seems that the stock MK2 heater cannot keep up with the new fan. I can get it to print for longer by dropping the max/min fan speed but I can't make the issue go away. And also I figure the fan is there for a reason. Fan shroud looks to be centered and properly installed.

I noticed that my heater lead insulation is blue (with red sleeves at the cartridge), and that the resistance measures 5.7 Ohms cold. This is consistent with a 25W cartridge (12*12/5.7 = 25W). So I ordered a 40W heater from filamentone. It says 40W/12V on the cartridge, but I measure 5.2 Ohms (28W). Power supply to the heater is 11.9V.

1) What should the cold resistance be for a 40W heater? Can I be confident in saying that they sent me the wrong heater? I assume these are rated at cold resistance, I haven't checked current while plugged in. 

Ambient temp in the room is pretty cold. Maybe 15C. But I have a heater blasting on it and the temp is 19-22C.  Regardless, I don't think ambient temp would be as much of a factor.

2) could ambient temp be causing this issue?

My next order of business will be to order another 40W heater

3) I am in the US. Can anyone recommend a reliable supplier that can ship quickly?

Any and all advice is appreciated. Thank you!

Posted : 09/01/2021 6:04 pm
JoanTabb
(@joantabb)
Moderator
RE: After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan


these resistances are possibly a little high, because the cold value is usually a little lower than the hot value, but they will put you in the correct ball park... 

Try Printed Solid, or Matterhackers or any of the E3D resellers 
https://e3d-online.com/pages/resellers

regards Joan 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 09/01/2021 11:15 pm
Tom Anderson
(@tom-anderson)
Active Member
RE: After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan

Try my nozzle fan shroud fix

https://www.prusaprinters.org/prints/56604-mk25-fan-shroud-fix

Posted : 07/04/2021 10:30 am
Chicago Keri
(@chicago-keri)
Trusted Member
RE: After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan

...

I noticed that my heater lead insulation is blue (with red sleeves at the cartridge), and that the resistance measures 5.7 Ohms cold. This is consistent with a 25W cartridge (12*12/5.7 = 25W). So I ordered a 40W heater from filamentone. It says 40W/12V on the cartridge, but I measure 5.2 Ohms (28W). Power supply to the heater is 11.9V.

1) What should the cold resistance be for a 40W heater? Can I be confident in saying that they sent me the wrong heater? I assume these are rated at cold resistance, I haven't checked current while plugged in. 

Ambient temp in the room is pretty cold. Maybe 15C. But I have a heater blasting on it and the temp is 19-22C.  Regardless, I don't think ambient temp would be as much of a factor.

2) could ambient temp be causing this issue?

My next order of business will be to order another 40W heater

3) I am in the US. Can anyone recommend a reliable supplier that can ship quickly?

Any and all advice is appreciated. Thank you!

Your resistance readings are consistent with a 12v 30w E3D heater, which has blue wires. The 12v 40w E3D heater has red wires and should check at around 3.6 ohms.

A reliable supplier in the US with genuine parts is Printed Solid.  You can get a plain 12v 40w E3D heater with 2 meter wires that you should  terminated with ferrules, an E3D 12v 40w "high precision" heater with 1 meter cables and a connector near the heater, a Slice Engineering 12v 50w heater with long cables and a connector near the heater or a complete "drop in" complete PRUSA-specific 12v E3D hotend with heatsink, heatbreak, heater, nozzle and thermistor. Printed Solid also ships quickly in the US.

Over time, I have used most of the above! Nowdays I use the 50w Slice heater in a Mosquito on my MK2.5S.

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Nein! Nicht Versteh!
Я немного говорю по-русски но не очень хорошо, и...
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Posted : 07/04/2021 3:21 pm
Cswany
(@cswany)
Active Member
RE: After upgrade, Mk2 nozzle heater can't keep up with Mk2.5S fan

I had the same problem and I realized that I had turned off in prusaslicer when the fan got up to full speed.

Look under filament setting tab- cooling -half way down  this setting "full fan speed at layer" my setting for PLA is 6 layers to full speed. I have not had any problem with thermo drop after I had changed this

...
Posted : 24/04/2021 7:02 pm
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