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joergen

volumetric netfabb?

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I've heard rumors about a volumetric netfabb update... does anybody have any details, especially when this might come?

(I have issues with the speed scalability of my current netfabb profiles, meaning it prints ok at 100%, but not enough extrusion at 200%, and needs manually adjusted in the live tuning window)

related: live tuning the speed and extrusion doesn't relate in faster printing (printing netfabb code via repg26b1), it seems there is a brickwall of what netfabb and marlin think as the max extrusion per sec. if i bring the printing speed to 200% and wait 2 sec for the printer to catch up, and then increase the extrusion rate (to match an imaginary factor), the tool head speed gets slower to get to the requested extrusion rate, instead of simply spinning the motor faster (nowhere near the max yet). also a thin (0.5mm) at medium speed (100mm/s) prints much faster (guestimate 2x) than a medium (0.6mm) at medium (100mm/s) speed (which makes no sense to me at all).

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I've heard rumors about a volumetric netfabb update...

I've been working on something sorta like that for a while but work (the work that pays my mortgage, not the work where I get to play with 3D printers) keeps getting in the way - only so many hours of coding I can do in a day before my brain turns to jello! Next Friday is probably my last work day this year (woot!) so I'd be reeeeally suprirsed if I didn't have something at least partially working in the next few weeks.

No idea if netfabb themselves are working on such a thing, too. If not, they should be. It's the way to go!

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What exactly would a volumetric profile do for a print?

For a print? Nothing much..

The short answer is that "volumetric" has come to mean calibrating via math instead of via trial & error - the software calculates the volume of threads it wants drawn then does a bit of math to figure out the right amount of filament to pull *into* the extruder to get that volume. Once you get a bit of setup done, you can just tell it any layer height or thread width or speed you want and it figures out what to do with the extruder.

I was just posting about this (in the skeinforge context) over in the mbi google group so I'll copy/paste that here..

 

The basic idea is that slicers used to output gcode that talked about extruder speed and x/y/z coordinates separately - it was stuff like "Start the extruder at speed A. Move to position B at feedrate C. Move to position D at feedrate C. Stop the extruder." over and over in the gcode.

 

With the dimension plug-in, those two separate commands merged into one single gcode command - this was "5D" since each line of gcode told the firmware how far to move in X, Y, Z and E (extruder) as well as saying how fast (time) the move/extrusion should be. The problem with this was that the E part of that command referred to extrusion length out of the nozzle and, for a given specific volume of plastic, that length can vary based on nozzle size, flow rate, temperature, plastic formula and 97 other things.

 

With volumetric 5D (SF40), that troublesome E component changed to specify the length of raw filament into the extruder drive. Because the slicer (SF) knows the volume of threads it's outputting (h * w * l) and now knows the diameter of your filament (from the Dimension tab), it can very exactly calculate how much filament needs to go into the extruder to draw the correct shape/size line in the the correct amount of time.

 

So.. Volumetric 5D slicers like SF40+ are frickin' awesome, since there's no more screwing around with calibration cubes to get the flow rate to match the feed rate. You want to print at a different layer height? Just change the layer height and you're done. Want different thread widths? No problem - just change w/t and SF figures out the right flow rate. It's really quite nice.

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