Slic3r Volumetric Extrusion

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Slic3r Volumetric Extrusion

Postby Mooselake » 2016-Jan-Sun-17-Jan

In the release notes for the current slic3r they mention an experimental option for Autospeed volumetric extrusion - in other words adjust the print speed to keep the extruder flow constant. With my current interest in themaximum flow rate of the all metal ubis hot end, it was an obvious testing project for the Mooselake R&D Lab.

In the slic3r advanced Print Settings tab under Speed, if you scroll down to the bottom of the window there's a couple options for Max print speed and Max volumetric speed

Slic3rVolumetric.jpg


These allow slic3r to determine what speed will produce the desired extruder flow rate, intended to keep the flow (and therefore) extruder pressure constant. My AMU has a maximum continuous flow just under 14 mm^3/sec (thanks, RJ!), good results in the Ultimaker 10 mm^3/sec flow test (does this mean an old KSCP does at least as good as an UM2?). 8 looked a little better than 10, maybe, so that's what went into the max flow box, and since I've been using a max of 80 lately (at my previous 100 the AMU would skip in some areas...) that went into max speed. Per the directions all the other speeds were set to zero. The test object is a part for a K40 Laser mod (let's call the design mistakes learning attempts, it's taking a while to get this table adjuster gadget right), and the filament is HH3D transparent orange PLA, 0.2mm layers (with variable infill it's no slower than 0.3). Let the slicing begin. Whoops, set the bottom layer to 30 so it'll stick, try again. Success, sorta. While the prior prints with this filament had an excellent surface finish, this one would make a good micrograter.

VolumetricTest1.jpg


As you can see, the outside is pretty rough. Still successful, since appearance doesn't matter, but we can do better. Take 2, violating the MLDL only change 1 thing at at time rule, the max speed was bumped up 100 mm/s, and the perimeter speed set to 40. These are the speeds in the screen snapshot above.

VolumetricTest2.jpg


Left is the second (not counting the non-sticker) attempt, the cheese grater is on the right. The color difference is because it's transparent with varying innards, but the surface is smooth and artifact free. The top is a little nubby, probably needs some speed adjustment. So far Autospeed looks to be a success. I should have dug out the stopwatch and timed it, but it seems faster than the fixed speed sliced version. Time to bump the speed up another notch, I need 4 of these things. Hint, leave a pocket under the turning part of the bearing. If you put a dab of epoxy on the bearing (the first batch was done with craftware and slightly loose) it glues the center to the pocket and you have to bust out the bearing and chip off the glue. These were a tight fit, just right with a little scraping, just enough undersize to grip well without splitting the side at the seam.

Kirk
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Slic3r Volumetric Extrusion

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Re: Slic3r Volumetric Extrusion

Postby ktfergus » 2016-Jan-Mon-23-Jan

If you're just looking to decrease print times, I highly recommend picking up a 0.75mm nozzle; however I applaud your efforts to maximize printing efficiency. I grabbed one for my new Ubis 13s & a print that would normally take 6 hours with the 0.4mm nozzle took just 2 1/2 hrs with the bigger nozzle (.5mm layer height vs. .25mm)-I just don't have the patience to print lower than .25mm when I'm not overly concerned with the part's appearance.

I still have to do some testing to make sure the strength is equivalent, but for now that's my go-to nozzle for giant prints.

I also picked up a 0.2mm nozzle to try some micro printing, but haven't tried it yet.

-Kelly
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Re: Slic3r Volumetric Extrusion

Postby Mooselake » 2016-Jan-Tue-07-Jan

The metal Ubis has a lower maximum flow than the older varieties, so a larger diameter nozzle will be limited by it's lower melt capability. PB's pending dual heater core hot end is their answer to that, the 13p iirc.

A couple years back there was an issue with the 3.0 original Ubis with a Wades extruder and a large diameter nozzle being limited by Marlin's maximum step rate. It's in the archive.

Maybe you just need another printer, like the furball's delta, and print two or more parts at a time :)

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