In Slic3r (0.9.8) for nozzle diameter are you supposed to input the actual diameter

@Whosa_whatsis same thing with me if I use the tiny little notification dropdown; I actually had to hit up the community page in a browser to see his replies. Weird. :confused:

@ThantiK I don’t even see them there. Only when I view the thread logged-out.

Hey just got home from work and 100mm = 108mm so I’m going to adjust my Marlin settings and see how it goes. Thanks for the suggestions and lively convo.

“I’ve had to adjust the filament output ratio to .9-.92”

Well, you said you were about 10% off. So that sounds about right! 108*0.92 = 99.36

@Chapman_Baetzel to have a 15% strain in 1.75 mm ABS you need to have a force of 59lbs. I used the modulus of ABS listed here: http://www.engineeringtoolbox.com/young-modulus-d_417.html If anyone wants to check my work: Modulus=stress/strain. and Stress=F/A.

Regardless, when measuring the E steps in the manner accepted community wide you are measuring where the filament isn’t compressed. Therefore, unless there is slippage or missing steps as said several times there is something wrong.

Measuring without the hotend eliminates variables for new printers so that they can get the E steps calibrated without wondering about other issues.

15% slippage does seem like lot. Perhaps a particularly soft batch of ABS? On the other hand, I would generally advocate calibrating systems under conditions as close to operating conditions as possible. On yet a third hand, I also have a MG extruder, and see no evidence of 15% slipping on 1.75 ABS. When I back the filament out (after a jam, no less), the tooth marks in the filament are straight, not wiped.

Also, 15% strain is approaching the yield strength of about 18% (depending on the particular blend). At the yield I would think weird things would start to happen in a mechanical sense. I should mention that this is largely based on tensile forces and not compressive.

So, back to the ORIGINAL question…

It’s not clear to me why you wouldn’t want to use the measured diameter of the extrudate rather than the stated nozzle diameter.

Seems similar to measuring the filament rather than just taking the stated diameter.

I did a test this evening. My machine supposedly has a 0.5mm nozzle. I extruded some ABS in free air, then measured its diameter. It measured at 0.61mm.

If I tell the slicer my nozzle is 0.5, and it does all its calculations based on that value, but my actual extruded diameter is bigger, isn’t that going to throw things off?

The extrudate is not thicker because the nozzle bore is bigger. The extrudate is thicker because the plastic is made of polymer chains that have elasticity, and they contract axially and thus expand radially after leaving the nozzle. The calculations that the slicer does take this effect into account based on the stated nozzle bore, so giving it the wrong information by telling it the extrudate diameter will foul those calculations.

Ok, that makes sense now.
Thanks!