Printing gone Bad

Hello Dear Reprappers

I have been building my reprap in the last 5 months, now i have tried in 2 months to get my reprap printing propperly, but without succes.
I got a Prusa Mendel, with Arduino Mega, Kliment Sprinter firmware.
Hot end from Ebay (See here) and ABS from czechreprap.eu.
I'm using Pronterface to print.

When i set the temperature in the interface to 230, the ABS does not melt, then i read the temp with an IR-temp it says about 120 on the outside of the heater. Then i turn it over 300 it slowly starts to melt. Then the outside temp from the IR terometer i around 220, but then the filament starts to smoke and smell bad. The print gets very bad. Then i bought some of the parts fra ultimachine i got a free sample af filament - no problem extruding at about 230-250.

I can't find out what's wrong???
I hope some of you can help me

You can't measure the temperature with a typical IR thermometer. The aperture is too big, even at close range for the hot end to fill it. Also the emissivity of metals is lower than the value they are typically calibrated for.

The best way to calibrate the temperature is to use a multimeter with a thermocouple probe and place it inside the hot end (preferable before you even put plastic in it).

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[www.hydraraptor.blogspot.com]

Have you checked that the thermistor defined in your firmware (configuration.h) matches the thermistor you have in your nozzle heater?
It sounds as though you're not getting the correct readings at all.

I use a laser guided IR-thermometer (Link to IR-thermometer).

I have put "black tack" (mat black heatresistant tape) around the heater to avoid emissivity problems.

I think i use the right settings?
Settings from firmware:

//// Thermistor settings:
// 1 is 100k thermistor
// 2 is 200k thermistor
// 3 is mendel-parts thermistor
// 4 is 10k thermistor
// 5 is ParCan supplied 104GT-2 100K
// 6 is EPCOS 100k
// 7 is 100k Honeywell thermistor 135-104LAG-J01
#define THERMISTORHEATER 1
#define THERMISTORBED 1

Is the hot end big enough to fill the measurement aperture? Usually you would need to hold it very close and then the laser is offset. I have never managed to get an accurate reading with a laser IR thermometer but I only have a cheap one. I have used an IR probe to measure the temperature of small chips on a BGA rework station, but that has a lens and is only about 50mm away.

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[www.hydraraptor.blogspot.com]

To two laser beams should be precise, but i'm not sure...

But it's a little odd that the sample from ultimachine was no problem?

In my thermistor settings, could it be 6 or 7?

[reprap.org] go here and match your thermistor to the pictures