Welcome to the SeeMeCNC Community

In Repetier if I have my extruder set to 55 mm/min and I tell it to extrude 55mm it spits out almost exactly 2.5 inches worth of ABS. Shouldn't it spit out exactly 55mm? What setting should I change?

Also, how can I calibrate my hotend for the ideal temp? What's the best test target for that?

I did a trial and error method of getting my feed right. I created two marks 100mm apart on the bowden tube then set the extruder to extrude 100mm. My first try wound up being 112mm. I then adjust the firmware axis steps for the extruder and repeated the test until I got 100mm extrusions.

If using the Marlin firmware look for the following line in the configuration.h file and change the last value;

define DEFAULT_AXIS_STEPS_PER_UNIT {53.333, 53.333, 53.333, 292.0} // 53.333(xyz)/292.0(E)

The ideal temperature is a trial and error method. I haven't perfected it myself yet. It depends on the material you are printing and the speed of the print. Just remember not to go to hot as you risk melting the PEEK part of the hot end. I read in another post the PEEK will begin to soften at 245C. I also read to use a thermocouple to measure the actual tip value as the thermistor could have variation due to assembly and position.

I believe the 55mm is the length entering the extruder

@unititle86 - 55mm/min is the rate of extrusion. Then, when you tell it to extrude 55mm, it should take one minute. It should feed 55mm of the source filament. What comes out the nozzle will be CONSIDERABLY longer! However, the volume of material in should equal the volume of plastic out. Read my build thread - I have a post on how to do this calculation. It is a good way to check calibration. I also have a post on optimizing the hotend temperature from last week, I encourage you to take a loot at that, it should be pretty clear.


regards,
Michael