More thoughts on extruder "calibration"?

I ranted some earlier about "calibration" of the extruder and want to follow up. Please shoot me down or add to the discussion; I think this topic is worthy of critical scrutiny.

I now have some printing time under my belt with media of different types and from different suppliers. There's the obvious need to re "calibrate" upon changing media type (abs<>pla) and a surprising need to recalibrate on changing color of the same media. So it seems that if I frequently want to play with different media, I best be prepared to frequently re "calibrate" my extruder. I'm sure many in-the-know have settled on suppliers having media that produces prints of consistent quality and all that, but...

As near as I can tell, there are at least four different ways to achieve "calibration" (a fancy word that means “consistently make nice looking prints”):

1) E_steps in firmware
2) Diameter of filament in the slicing program
3) Extrusion multiplier in the slicing program
4) t:h setting in the slicing program

They all seem to do the same thing: Change the rotational speed of the extruder motor for a given linear distance traveled by the nozzle.

This level of complexity makes the calibration process more art than science and must unnecessarily complicate slicing code. In the realm of "I wish": I wish there was an easy and intuitive way to quickly ascertain the need to calibrate and then the extrusion vector required to achieve a state of calibration. It would be oh-so-nice to see a single textbox or slider in the slicing program, or better yet the printer interface, that allowed easy manipulation of extrusion rate. I don’t possess the coding expertise and if I’m the only one interested in this, then I guess I’ll just live with it. But that’s a sad outcome given the level of interest people are showing in this technology and the rate at which noobs are entering the fray…

You need 1 & 2 because they can be measured much easier than the resultant volume, which is what is being controlled.

3 is only useful because 1 is stored in firmware. I store 1 in my host software and so don't have the equivalent of 3.

4 is a different thing entirely. It isn't something you need to calibrate, it is something you specify to set the level of detail / strength trade off and depends of the die swell. It also affects bridging and overhang ability.

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[www.hydraraptor.blogspot.com]

I have NEVER had to recalibrate my e-steps or use the extrusion multiplier because of the brand / color of plastic I am using. The only thing I change is the filament diameter and I have been printing for over a year and have three/four machines going. Once you have it set up correct and have a good mechanical side it will print consistently. I would say you may have a poor hobbed bolt that is causing the inconsistent drive between filament and it has nothing to do with the settings.

Yes you do have to change some settings when switching filaments but they are:
Temperature.
Filament diameter.
Speeds.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

The E step per mm varies between PLA and ABS due to the teeth sinking further into softer plastics so I can imagine some colours might make a difference to the hardness. They certainly affect temperature and viscosity.

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[www.hydraraptor.blogspot.com]

I have switched from 4043D PLA which is really hard and brittle to China PLA which you can tie in a knot without breaking and never had to change a thing. Maybe it is because I use a deep groove hobbed bolt that grabs the filament around the sides that I have better success with different hardness's of PLA. I have never used ABS so I don't know about the switch between them.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

I measured a 5% difference between PLA and ABS for a 15mm hobbed pulley: [hydraraptor.blogspot.co.uk]

For an 8mm hobbed bolt I have a 21% correction factor for PLA.

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[www.hydraraptor.blogspot.com]