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

In Slic3r (0.9.8) for nozzle diameter are you supposed to input the actual diameter of the nozzle, or measure some filament extruded into open air and put that in instead? I’ve not been able to find a clear explanation for this.

I’ve just started working with 3mm ABS on a Buddaschnozzle with a non-bowden Wades style filament drive and 0.35mm nozzle with .35mm and .2mm layer heights and it seems to be over-extruding and I’ve had to adjust the filament output ratio to .9-.92 to keep prints from overfilling and blobbing out. It prints pretty good at .9, but I know that’s a fudge factor number. I’ve accurately measured and calibrated the feed of filament through the Wade style drive and a 10mm feed = 10mm of filament from the drive. I didn’t have any of these problems when I was printing 1.75 PLA on my QU-BD extruder so I’m trying to figure out how to get it right. - Thanks!

If you bought the nozzle as a “0.35mm” nozzle, you enter 0.35mm. They’re not asking the extrudate size, they’re asking the actual diameter of the nozzle.

Also, when calibrating E-steps-per-mm, you want to be calibrating over 100mm, not 10mm (or at least 70mm). Too easy to get the esteps wrong on that small of a movement. Best way to do this is with the hot-end off of the extruder, so you can freely extrude this much without bumping into the hot end.

And measure the diameter of your filament at a few different places. The drift of filament diameter can be quite high. I typically only change filament diameter when tuning. My e-steps and nozzle diameter are never changed.

When measuring the filament(with the extruder off) I was scoring with a blade, running 10mm and then scoring again and measuring the distance between the scores with calipers, but I’ll try 100mm and see how that goes.

This filament (Ultimachine) is pretty stable and good on both dimensions(not flat or squished) at about 2.85mm along several meters length it doesn’t change much. Thanks for the input!

Also, as for the nozzle diameter, that’s is what I thought but then I got to second guessing myself when it started extruding too thick on the print, thanks for reaffirming it.

@ThantiK I was told that it was important to actually extrude when calibrating, to make sure you have proper back-pressure and all that.

Is that untrue? Is it fine to calibrate E steps without actually wasting filament?

@Miles_Wilford it’s fine to calibrate e-steps without extruding. In fact, it’s probably best. If your hot end causes skips, jams, etc while you’re trying to calibrate, your numbers will be off.

Bowden tube setups are great for this I’ve found, because you typically have more than 10cm until the filament even reaches the hot end anyways.

@Miles_Wilford Sounds like whoever told you that is a little behind the times. A stepper motor will move at the same speed regardless of the resistance (unless it skips a step, which is a problem that needs to be fixed). Older extruders based on brushed gearmotors would slow down due to back-pressure, which is only one of the many reasons they are not appropriate for volumetric control without an encoder to give you a feedback loop.

@ThantiK You need to have the hot-end attached to get an accurate measurement. Compression of the filament and resistance from the hot end can make up to 15% difference in extruded length. I tested that myself on a MG Hotend with a brutstruder. 100mm into the air was less than 85mm with the hotend attached. Same number of e-steps both times and I told it to move 100mm. Can’t remember if it was 3mm or 1.75, but the fact is that the hot end makes a difference.

@Chapman_Baetzel , if your filament drive is slipping, that should not get factored into the esteps value. The esteps should be the same for all machines with the same hardware.

If filament- or environmental-differences cause an effective change in length going into the drive, that should be dealt with via a slicer setting like, say, filament packing density…

@Chapman_Baetzel , you may want to update your information here, as you’re wrong. Your extruder causing lost steps like this is a problem with the extruder, and should never factor into your esteps-per-mm setting.

It is not losing steps. The distance extruded is different with a hotend on vs with a hotend off.

Then there is something wrong with your machine (compression or not), and you’re still giving people incorrect information.

So pushing filament against resistance is equivalent to pushing filament against no resistance?

Yes. Stepper motor driven filament, regardless of resistance, will always drive the same length unless there is slipping, missed steps, etc going on.

I can’t speak to the extruder you’re using, but I have measured a difference in extruded distance with no hotend vs with a hotend. All other variables of the machine being constant.

Then you’re missing something. Ask in #reprap if you don’t believe me. Make sure to ask someone who actually knows wtf they’re talking about though, like Kliment or Triffid_Hunter. Even @Whosa_whatsis up above has stated the same thing. You’re being told this by 3 different people, yet you continue to argue it. Maybe being told by the whole #reprap community might change your flawed opinion.

You are ignoring the flexibility of plastic. But that is tangent to the original question, and my initial point.
If you want the measure extruded distance with the most accurate representation of actual operating conditions of the machine, the hotend must be attached to the extruder.

The flexibility of the plastic doesn’t matter. The stuff could be string cheese and still not matter. Given that there is no slipping, the pressure that it applies post-grip will not change the distance unless there is something wrong.

On TOP of all of that, it is impossible to measure 100mm worth of plastic moving back and forth to get the most accurate measure, if you’re extruding through the hot end. There just isn’t that much distance before the extruder would eject the filament.

The further you extrude the filament through the driver, the more accurate of a measurement you will be able to achieve. Which ties back into the distance being extruded not being affected by back pressure of any sort.

I’m not seeing anything from chapman baetzel. Maybe he blocked me? Nothing in my block/ignore settings…

Anywho, I logged out so that I could read the messages up to this point. Any difference in length through the extruder for the same number of steps with/without a hot end attached indicates a mechanical problem, either filament slipping or skipped steps. Compression of the filament between the drive gear and the nozzle will not affect the amount of plastic moving past the drive gear unless there are other mechanical problems with the mechanism.