Issues after E3D upgrade

I need some help in tuning my K8400.

Everything was working fine before the upgrade. PLA printing at 195C@ 42mm/s with a 0.35mm nozzle.

I wanted more and better prints, so I bought an E3D V6 and printed this setup.
At first I used the original thermistor that came with the k8400. That gave me fairly good results, but I got into some feeding issues. Firtst print no issue, second print blocked nozzle. I can see the tension being build up in the ptfe tube and than there is a click from the extruder.

Preheating the printer to 210 mostly solved that issue. But the results for prints, like shafts, or any of these result in a hairy print. From layer 50 (or so) the extruder just stops feeding anyway.

So I changed the thermistor to the original E3D. Checked the fw setting only to find that it is already set to the correct thermistor setting “TEMP_SENSOR_N 5”, which is strange, because the original thermistor is clearly a different one.

Now I need to print at at least 230C to get the PLA even flowing. If it prints, the prints look fine up until the print get a little tricky, with bends etc… The prints still fail most of the time because the extruder just stops

I will post some pics later.

So in short: Changed to E3d V6 with .30 nozzle, prints fail or look really bad. I need to print at 230C using pla. With the old thermistor @195C

I Check for mechanical issues, but I cant find any. Nothing is broken or sticking.
I use a 40mm cooling fan

I am out of ideas at the moment. Any help is appreciated.

I check the thermistor resistance e3d = 106ohms @22C The original thermistor show 93ohms@22C

So what setting should I use in the firmware?
Did another test, I can touch and hold 50C? That can be right.

This is what I am experiencing It is my setup.

It is a bit late for you rgrs, but it might help other ppl out there struggeling with the same issue.

first of all the IR temperature gun measures an average surface temperature which would be inadequate for this purpose as you dont just measure the hot end.

secondly Velleman has made everthing non standard on this printer.
eg: using 15v instead of 12 or 24 and 5volt rail being 4.12v rather than 5.0v and not forgetting to mention the pain in the butt non 3d printer standard plug types and the pins we could solder to the board but that are not delivered with them.

The problem you are experiencing is correct as the temperature sensor is normaly a 4.7k and 100k ntc in series between 5v and ground and the measuing adc is done between the 4.7k and 100k ntc. but on this board they have added another 4.7k between the measuring point and the actualy adc resulting in way lower temperature than expected.

this problem can be solver in 3 manners:
1: make your own custom temperature lookup table with a temperature probe and flash it.
2: bridge the annoying 4.7k resistor and use the normal table 5.
3: use another analog ping with a different 4.7k resistor and build it your self, or use an measuringt device like a pt100 rtd-type measuring device with any other analog pin. as using the default analog port would still have that 4.7K in series with what you actualy wanted to measure.

ps: keep in mind that the 5V probebly isn’t 5V but rather 4.12V as ive measured that on both my K8400 boards

Currently im using the 1st solution but would only be viable if printing PLA as if you went with ABS or other higher temperature materials you would lose out on the resolution of the 10bit adc due that 4.7k resistor.

Keep in mind that im not a certefied electrician but from looking at the technical data sheets between different vendords and boards this was about the only explanation i could find for this issue.