I need some help with esteps calibration.
I’ve got a custom built 3D printer with a Bowden setup. I can post a pic later.
I took of the PTFE tube off the cold end and instructed the printer to extrude 100mm.
It fell short by a few mm.
I calculated my new esteps and it over extruder.
I finally started going up in small increments until I got my 100mm extruded.
Remember that this was only on the cold end, without the PTFE tube attached.
I tried my first print yesterday, and got under extrusion on my layers.
I of course understand that the pressure in the tube + pressure to push the plastic out of the Hotend would make some difference.
How do I calibrate the extrusion to ensure 100% proper extrusion with being over or under?
What’s the most reliable method?
You should be getting the same extrusion with or without the ptfe tube or the hot end, esteps are esteps, if the total extrusion changes with additional resistance on the filament your motor is skipping and needs more power or to be switched with a more powerful motor or something to fix the insufficient force.
But you also need to calibrate your filament diameter and extrusion multiplier in your slicer. After you measure the filament in a few places and put the average of those measurements in your slicer, try printing a small single walled square, you can find plenty of things like that on thingiverse. Then measure the thickness of the wall and compare to the expected thickness your slicer thinks it’s producing. Use that ratio to set your extrusion multiplier in your slicer and try again, then repeat until you get a result you consider close enough.
I would also use all of the decimal places (at least 4-5) in your calculations when dividing.
What @Stephen_Baird said is not true. There is a difference between extruding with or without hotend.
You did fine with setting the steps to the point where you get the matching result. This is your base calibration. You never need to change that again.
Now to the final calibration:
Then, measure your filament diameter. It is common, that eg 1.75 Filament has a lower diameter of eg 1.7 or 1.65 or such. Put this number in your slicer. Start printing. Adjust the flow during printing with the flow-setting and try to achieve a working extrusion. Put this number in your slicer, too. Remember to set the manual flow setting back to 100%, slice again with the right diameter and previous noted flow. Print. Rinse and repeat.
@Mark_Rehorst Triffid Hunters Calibration Guide is so outdated, that it is nearly wrong to use it. And he suggests to adjust the steps over and over. That is not the way to go.
I know, he put much work in it and in a time before heated beds and PEI-coating, he was mostly right. Sadly, it is outdated in very much aspects :-/
I tend to just extrude with the Bowden tube in the hot end, yes it wastes plastic, and YYMV, but I just measure from the base of the extruder as with a direct drive and that seems to provide me with the best all around results.
I did a looooooooong post inthe german sub-forum about triffids guide and sry, but I am not motivated enough to write it down again in english and in just a comment that is gone in a day. I am working on a guide to publish on my own, to adress this issue. A few points to mention, so hopefully you begin to think about it: There is a knob to turn, called flowsetting. But you don’t use it and instead you put some M-Code via console to change the steps midprint?! Doesn’t sound easier… Further, Triffid says, that 0.2mm is the length to keep in mind with thermal expansion of the hotend. So all hotends are the same? Then: He doesn’t even mention a heated bed, given that this has thermal expansion, too. Furthermore, the amount of extrusion is highly depending on temperature. Do your calibration with the 100mm filament, then reduce the temp by 10 deg and your off by some mm. I can go through every point of the guide, but, seriously, I am not in the mood right now, sry. Not offending!
as was said. 100mm is 100mm. once you get that you adjust your flow rate to nail it down. this is why you do not recalibrate for each roll of filament
@Rene_Jurack What you said is basically what I said - if the esteps are correct the remaining calibration is in the slicer.
Nothing that comes after the extruder will change how many steps it takes to move your filament a certain distance, that is entirely controlled by your microstepping and hobbed pulley/bolt. The only way that varies from what you expect is if the motor is skipping.
@Stephen_Baird no. The hobbed bold does not punch a perfect toothed rod into the filament. There are multiple measurements about this (including my own) and discussed @ http://reprap.org forum…
@Rene_Jurack could you provide more specific directions to some of this information. The reprap site is huge (and old), I’m on my phone right now and searching is not working out. I would like to get a better understanding of what you are describing. Thanks!
@Alan_Thomason These discussions are spread all over the forum, you know, one is discussing an issue and someone other is wandering off the subject, one thing lead to another and next thing one sees is some integral-equation talking about pressure inside the nozzle-tip 
Hmm… lemme think… a noticeable one (or one I remember) is this: http://forums.reprap.org/read.php?249,528860
@Rene_Jurack thanks! I missed that you were referring to the German language area. The one thread seems to say that pressure can affect the extrusion calibration. I’m trying to understand mechanically what that means - I think the implication is that molten plastic is compressible. If that is the case, perfect calibration may be very hard to attain.