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Hi Guys,

I just added 2 more of the 30mm layer fans for a total of 3. Naturally they turn on after the first 2 layers are printed but once they turn on, the tempature of the hot end starts to dive. It have to stop the print because it just keeps cooling down. Last time it got down to 140 before I stopped it.

Its maintaining print temperature fine until the fans turn on. Does this mean the power supply does not have enough power to run everything at once? If I turn off the fans, the temp climbs again.

Strange....

I assume you're still using the stock hotend and resistors. If so, you're head can't keep up with the heat loss from the extra fans,,,,

But they are layer fans... They aren't blowing right on the hot end so shouldnt it be fine?

Having three fans providing air "against each other" is probably causing turbulence and air bouncing off of the bed/object onto the nozzle, so your layer fans are most probably cooling the nozzle. If you want to test it, move the hot nozzle close to the platform, start the fan, and try to shield the nozzle from the air somehow. If you manage to keep the air away from the nozzle, you'll most probably see no temperature drop.

You guys nailed it. Those fans were cooling the nozzle that much. They were blowing against each other. Once I removed one, the air had somewhere to go and its doing better.

Now at 176 instead of where it should be at 190. But its an improvement over the 144 I did have.

Boundless wrote:You guys nailed it. Those fans were cooling the nozzle that much. They were blowing against each other. Once I removed one, the air had somewhere to go and its doing better.

Now at 176 instead of where it should be at 190. But its an improvement over the 144 I did have.

i have the same exact problem, but i have been running my dual fans like this for 2 months, no problems, now when i start a print it rises to the target temp, but i can tell the hot end seems to take longer, even with fans off its not as fast as before, then when it starts printing it drops lower to 140 for sure as well and if i switch fans off it will rise again, or when i drop fans to 25% manually. so before i run out and get a new hotend setup with new resistors, could this in fact be a problem with the PSU or just my hot end coming to its life end? its the original on mine

My hotend used to go up to 245 (max i tried) now it only goes up to 233. And i do not have a alyer fan.

I think some of the rtv has gone so the heat is not reaching the metal... i will try squirting more rtv in there or redoint the whole rtv part.

What you should do is (in my opinion)
1 redo the calibration with the fans on and the hot end close to the bed to simulate the air bounce from the part.
2 wrap some kapton tape or some other heat resistant insulation around the hot part of the hot end to shield it.

teoman wrote:My hotend used to go up to 245 (max i tried) now it only goes up to 233. And i do not have a alyer fan.

I think some of the rtv has gone so the heat is not reaching the metal... i will try squirting more rtv in there or redoint the whole rtv part.

What you should do is (in my opinion)
1 redo the calibration with the fans on and the hot end close to the bed to simulate the air bounce from the part.
2 wrap some kapton tape or some other heat resistant insulation around the hot part of the hot end to shield it.

its not an air bounce issue because i can be 3-5 inches off the bed and same thing. besides i ran these 2 fans for 2 months no issue it just started randomly now

sorry about hijacking thread, ill start a new thread.