Cold Hot End

[fredini]

Hi folks!
I have a Rostock Max v2 that I have been very happy with but it has been having a few extruder issues of late so I'm turning to the crowd for advice.

I typically run long prints(~48 hours) in PLA. My first layer is 230 degrees then the rest of the print runs at 218 with the plate at 60 (fans are set to 100% as well). I've had stellar prints and have racked up a lot of time (16,000 meters of filament) on the machine since I got it in September.

A few weeks ago I had several failed prints (all extruder feed issues) before realizing that the fan cooling the extruder barrel was not working. I just replaced it and now realize there's another issue.

Now the hot end is failing to keep up to temp. In order to get the extruder to 230 to start the print, I have to touch the fan to stop it- otherwise it never gets hotter than 221. Then when the print is running it runs at 207. or 206. instead of 218. In fact I usually run the machine at 125 or 130% speed, but the temp was in the 194 area until I slowed it down and cut the cooling fan to 50%.

I'm thinking one of the heating resistors is probably bad. I'm not so electrically minded. How do I check this with a voltmeter? Or do you have any other advice?

[Nylocke]

Go to the V1 from forum and look at Gene's stock hotend upgrade video. He uses a heater cartridge and a screw in thermistor. You'll get much better results heating and a more stable and reliable hotend. The screw in thermistor is less necessary but IMO a heater cartridge is pretty much necessary for a reliable hotend.

[Earthbound]

If you haven't already done so, wrap the hot end with kapton tape. Cover from the bottom of the PEEK (finned) section down to the nozzle. Without tape insulating the head, the resistors will struggle to achieve target temp. I also suggest making sure the PEEK fan airflow is not blowing across the thermistor.

If you want to check the resistors, disconnect the heater wires and measure across the resistors. Should be about 3-3.5 ohms. If closer to 6-8 ohms, one resistor is bad.

[gleb]

I've got similar issue. Seems that are heating resistors are dead. Could anyone suggest which resistor could replace them?(I mean brand and parameters for new resistors)
Also if anyone got same issue: any guess why it might happen?In my case I was doing calibration using this algorithm http://forum.seemecnc.com/viewtopic.php?f=36&t=4677 and all of the sudden heating stopped working(fan and thermostat are fine)

[BenTheRighteous]

Replace your resistors with a certamic heater cartridge. Not much more work, but very efficient. Geneb has a youtube video on how to do the upgrade, and you can source from either filastruder or amazon.