incorrect hotend temperature reading

Hi
I am having an issue with my 3d printer. When the printer is set to 200ºC the printer seemed too cold, and when I checked the temperature with a temperature gun the nozzle temperature read 160ºC.
When I set the printer to 240ºC the printer prints well and the nozzle temperature becomes 205ºC.
I thought it was the thermistor so I replaced it and the problem is still there.
This problem started about a month ago, it used to show the perfectly before that.
I was wondering what could cause this and what can I troubleshoot to try to fix this?
My hotend is a E3d V6, board is a smoothieboard 5x, and host software is Repetier Host.
Thanks
Tanner

Have your PID Numbers been changed

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Roberts_Clif
Have your PID Numbers been changed

I did a PID tune after I switched thermistors.

Those IR thermometers are junk. Don't trust it to tell you anything. You don't know what's it's aimed at, or the emissivity of whatever it's pointed at. Accurate temperature reading isn't needed- just run a few experiments with your filament and find the best temperature to use.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Heat guns are usefull for the heatbed, but they just don't work for hotends. I use a thermal camera and it is still sometimes hard to determine correct temperatures.
The cheapest and best option i found was to tape the k-type sensor with kapton to the hotend

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

I am not trying to start an argument, but two years ago I was trying to decide what hot end to put on my new printer. I chose the Prometheus. I have yet to have it clog or jam. I am now printing in two colors with it as well.

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cwaa
I am not trying to start an argument, but two years ago I was trying to decide what hot end to put on my new printer. I chose the Prometheus. I have yet to have it clog or jam. I am now printing in two colors with it as well.

Not sure that's gonna help the original poster!

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Waitaki 3D Printer

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waitaki

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cwaa
I am not trying to start an argument, but two years ago I was trying to decide what hot end to put on my new printer. I chose the Prometheus. I have yet to have it clog or jam. I am now printing in two colors with it as well.

Not sure that's gonna help the original poster!

Nope, but it makes me cringe since I chose the E3Dv6 over the Prometheus, and am feeling like I bet on the wrong horse. I too am having issues with my brand-new E3Dv6 clogging. I haven't been able to run a single successful print yet. I chose the E3Dv6 over the Prometheus because I couldn't find a Delta Prometheus end effector and more people seemed to have the E3Dv6.
I am getting frustrated with the E3D hot end, but hope to solve its problems soon. The three common suggestions are:
Reduce your retraction distance, 0.8 for direct, <=2mm for Bowden
Increase temperature 20-30 degrees
Drop of canola oil on the dust sponge to "prime" the heat break

All are pretty simple, I will be trying them in that order tonight to see if I can get some joy from my new (non-functioning) hot end.

DLC

I guess you are using PLA? I make my own hot ends based on the E3D design - with some differences but.. I print mainly in ABS.
PLA can cause havoc in many types of hot-end and I wouldn't be surprised if the Prometheus has its problems also -not that I would know. If I use PLA, I am very concious of the fact that it can't be left hanging around in the heater block. To this end, I get the heated bed up to temp(60C), load the gcode and then, finally, switch on the heater for the hot-end (185C). As soon as its at temp, I would do a quick 10-20 mm prime then immediately start the print.
I don't go above 185C or "oil" the filament, and I don't bugger about with retraction. Having said that, I am told that some PLA needs a higher temp but the stuff I have bought works best at 185. I've had my problems with PLA but usually I can make it work ok. I certainly don't like the stuff much though, that's for sure.

Edited 1 time(s). Last edit at 08/24/2017 06:28PM by waitaki.

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_______________________________________
Waitaki 3D Printer

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waitaki
I guess you are using PLA? I make my own hot ends based on the E3D design - with some differences but.. I print mainly in ABS.
PLA can cause havoc in many types of hot-end and I wouldn't be surprised if the Prometheus has its problems also -not that I would know. If I use PLA, I am very concious of the fact that it can't be left hanging around in the heater block. To this end, I get the heated bed up to temp(60C), load the gcode and then, finally, switch on the heater for the hot-end (185C). As soon as its at temp, I would do a quick 10-20 mm prime then immediately start the print.
I don't go above 185C or "oil" the filament, and I don't bugger about with retraction. Having said that, I am told that some PLA needs a higher temp but the stuff I have bought works best at 185. I've had my problems with PLA but usually I can make it work ok. I certainly don't like the stuff much though, that's for sure.

Yeah, it is PLA. My previous "cheap Chinese Copy" of probably, a J-head worked great with it. I am having huge issues with it and my E3Dv6. I never even got a print to finish until I jacked the temperature up to 230C on the E3D. However, my DVM-thermocouple says that 220 (from the thermistor) was 190C. So, I question the accuracy of the temperature sensor on the E3D.
But, as the old saying goes "A man with one watch always knows what time it is, a man with two is never sure."

**edit**
It appears that my E3D problem was with the nozzle. I am still printing far hotter than I used to for PLA, but heck, this hot end can deal with it, so no big. I replaced the .4mm nozzle that came with the E3Dv6 with a "no-name E3D" .4mm nozzle and all is working great!

DLC

Edited 1 time(s). Last edit at 08/24/2017 11:16PM by dlc60.