Filament feed rate limit instead of nozzle speed limit

[jamezracer]

While I appreciate the ability to change nozzle speeds for support, perimeter, and top/bottom layers, I find myself constantly having to re-tune the nozzle speed for different layer heights and different infill extrusion widths. The reason for this is that both of my printers are limited in the filament extrusion rate, not in nozzle speed. They simply cannot melt filament very fast and little changes like increasing the layer height can push it over the edge very easily.

I would much rather set a hard limit in Simplify for the feed rate in cubic mm per second, and have the nozzle speed adjust accordingly. This means that the nozzle will slow down for thick infill extrusion widths, but still run quickly for perimeter layers, support structure, and solid infill. This would also help me get the fastest prints possible for a known extrusion limit.

This is particularly a problem on the Ultimaker 2 which is well known for underextruding and the feeder motor skipping even with it's own slicer and defaults. Even on my massive 3DP Unlimited X1000 which has geared steppers and a remarkable feed rate, I still encounter rushed jobs where I need to get a massive part printed where quality doesn't matter and I just need to push it as close to the extruder limit as possible.

Thank you!

[Scottty]

Having the same problem and a slightly different request proposal:

If due to big layer heights and/or wide extrusion width the extruder does not deliver enough heat and there are gaps between the material.

Therefore let me propose to add a parameter like „max. Volumetric Speed“ at the extruder settings area.
If this limit is not exceeded, the nozzle speed limit is active.
Otherwise the nozzle speed is decreased to reach the „max Volumetric Speed“
If no value is entered, this parameter is inactive.

For finding out the value for your extruder, use the command „G1 E100 Fxx“ several times with different xx find out the max F Speed where the extruder does not loose any steps and no slippage is recognizable (put a little mark 100mm above the extruder on your filament before this tests for measuring)

I read about people using a script to add "M203 E2" and "M203 E30" before and after each retract move.
I also think of adding this command wrapping directly in the firmware and create a new command setting this „max. Volumetric Speed“.
But in my eyes it is a slicer job and I highly appreciate to see it in the next version.
Thanks.

[mroek]

I second this. The max volumetric flow of an extruder is more or less a constant, and having such a setting as a hard limit that cannot be exceeded will simplify things a lot, and skipped steps will be more or less a thing of the past. To get really fancy, it could also be two settings, one for sustained volumetric flow rate and one for short-term, since an extruder typically can run with a higher rate for a short period of time.

[BaronWilliams]

I agree. This is absolutely needed. I get the impression that many people don't really understand the distinction between feed rate and print speed, and that's why these requests don't get taken seriously by the rest of the people on this forum.

I put together a request for both Default Feed Rate and Maximum Feed Rate found here: viewtopic.php?f=23&t=4877&p=21073&hilit ... ate#p21073

I tried to explain why it's needed in my request. Maybe I didn't explain it well enough. It seems like no one cares.

I am sure the Simplify3D engineers understand the need for this, but with so few people requesting it, it will probably not get implemented.

People are so used to seeing print parameters in the simple mm/s format. This comes from using CNC machines, which 3D printers evolved from. Even filament manufacturers don't give you the maximum feed rate for a filament, but instead give a recommended mm/s print speed, which is quite honestly useless without also knowing the layer height, extrusion width, extrusion multiplier, nozzle size, hot end type, etc.

Working with feed rate in terms of cubic millimeters per second is what we need. Why isn't everyone using this? This is the ONLY WAY to properly measure print speed. Your prints are made from the filament coming out of the extruder. This is the heart of the 3D printer. Everything depends on the filament flowing at the proper speed out of the extruder. If that feed rate is not set right, you cannot print anything.

Using print head movement speed, such as the Default Printing Speed setting, to adjust your printer is a seriously flawed method, which has somehow become the norm across most slicers, not just Simplify3D. To fix this is going to require a LOT OF PEOPLE being educated on this subject.

Using mm/s is really the wrong way to go. Who cares how fast the print head moves if you exceed the feed rate, your print fails. Even if you move slowly, but still exceed the feed rate, which is easily possible, your print will fail. It doesn't matter how fast or slow you move. The feed rate is EVERYTHING. You want your feed rate to be at or below the maximum speed, and then you can adjust these other print parameters. They should all be based on the feed rate and NOT Default Printing Speed. Its backwards, and it's not just Simplify3D that has this backwards, nearly all slicers have it backwards.