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Joined: Wed Jun 20, 2018 12:45 pm

Re: Default Feed Rate and Maximum Feed Rate

Tue Aug 27, 2019 11:49 am

Markos2f wrote:
Thu Aug 22, 2019 7:58 am
Hi there

I know its an old post but would you be willing to share your spreadsheet as I want to understand the formula to use for other materials. My current need is ABS with 0.25mm nozzle what parameters need to change to get the safe Extruder Flow Rate. I guess it is Extruder width, Multiplier, Layer Height. But Extruder width wuld have to be set to Manual to change it and that would negate using the Multiplier parameter. Please help if you can.

The extrusion multiplier will get applied even when you use manual extrusion widths!
"A bird does not sing because it has an answer. It sings because it has a song."

Posts: 14
Joined: Mon Nov 19, 2018 1:31 pm

Re: Default Feed Rate and Maximum Feed Rate

Sat Oct 10, 2020 1:08 pm

YES it might be nice to have all these type of functions in Simplify3D. Especially the price we paid for said software. Until then learn Marlin. You can add any Marlin command to your starting GCODE. This is what I am doing to change these setting. I am still tweaking the setting, Jerk, Acceleration, Travel FeedRate. To see how fast I can print. I just installed the E3D v6 Gold hotend and Zesty Nimble Direct Drive Extruder. So far I love this combination!! Really smooth printing at the moment with a Travel feed Rate of 120mm/s. I am going slow in my move to print faster. I find right now that for long runs the printer moves very fast, very smooth and very quite. It is with short moves where my printer is slowing down quite a bit. So I am really trying to determine how to increase that speed. I am thinking it is more about movement when not printing than when the hotend is laying down filament.

BaronWilliams wrote:
Tue Mar 22, 2016 2:44 am
To help prevent print failures and especially print jams, we need to be able to read and set the current Default Feed Rate. This is an important feature that's missing in Simplify3D, and probably most people don't realize how important this actually is. Feed rate is measured in mm³/s (cubic millimeters per second). It's a volumetric measure of exactly how much plastic is extruded per second from your extruder. The feed rate of a filament limits the speed at which you can extrude the filament, It's based on how fast the filament can physically melt in your hotend. it doesn't limit how fast the print head moves while printing. If you exceed the feed rate, your printer will skip, and then likely jam. But how do you know when you exceed the feed rate? Simplify3D hides the feed rate from you.

People are often using Default Printing Speed to adjust the feed rate. This is a poor way to adjust feed rate, because this adjusts printer head movement speed while feeding filament, it doesn't tell Simplify3D to use a specific feed rate.

In Simplify3D, all 4 of these settings are used to calculate the hidden default feed rate that Simplify3D uses internally:

Extrusion Width
Extrusion Multiplier
Primary Layer Height
Default Printing Speed
(this is the printer's head movement speed while printing, and is not the feed rate)

Increasing any of these values will increase the default feed rate. Decreasing any of these will decrease the default feed rate. However, the actual default feed rate is not given anywhere in the software, and we cannot set it explicitly.

A lot of people confuse the Default Printing Speed with the feed rate. Using the Default Printing Speed is truly a misleading way to adjust print speed for 3D printers. How fast your print completes a 10 cubic millimeter print is entirely dependent on the feed rate. Use of the head movement speed for adjusting print speed is based on CNC machines, where movement speed is everything, because nothing is extruding, you are cutting things. For 3D printing, you're most concerned with feeding filament for extrusion. You cannot exceed your printer's optimal feed rate for a particular filament or it will skip and likely jam your printer. You can however exceed the printer's optimal print head movement speed while printing as long as you don't exceed the feed rate and your printer will not skip or jam. It's critical that you know the feed rate to avoid printer jams. Your printer's optimal feed rate is determined by the temperature of it's hotend, the size of it's nozzle, and the size and type of the filament being used. Change any of these things and suddenly your required optimal feed rate changes.

Simplify3D calculates the feed rate internally. It's required data for adjusting the speed of the filament drive motor that moves the filament through the print head at a given speed. Currently we can adjust the feed rate by adjusting Extrusion Width, Extrusion Multiplier, Primary Layer Height, and Default Printing Speed together, and then let Simplify3D magically come up with the feed rate on it's own behind the scenes. If we increase any of these settings, we can possibly exceed the optimal feed rate and jam our printers. Since the feed rate is kept hidden from the user, most users are unaware of the optimal feed rate and usually just take a stab in the dark when adjusting these settings and just hope they don't exceed their optimal feed rate when printing with a specific filament.

For example, 1.75mm ABS on a printer with a 0.40mm nozzle tends to have a typical optimal feed rate of around 13.50mm³/s on a MakerBot or FlashForge style printer. With a 0.6mm nozzle you get around 15.00mm³/s. If you want to print at 0.10mm, or 0.20mm, or 0.30mm layer heights, and change from 0.50mm to 1.00mm extrusion width, whatever you chose, you should not exceed 13.50mm³/s on a 0.40mm nozzle or you're likely to jam your printer. But when you change these settings, how do you know if you've exceeded 13.50mm³/s? Simplify3D doesn't show you this information. It's hidden. If it wasn't hidden and you exceeded 13.50mm³/s because you increased the extrusion width, the extrusion multiplier, etc., then you would know not to print because your print will fail. But since it's hidden, most people have no idea they went overboard, and then run the print job, and then click...click...click...jammed printer! :(

If you're always using the same filament, same nozzle, same temperature, etc., then you have a fixed optimal feed rate. This will not change. If you switch to different filament, a different temperature, a different nozzle, etc., then your optimal feed rate will change. If that happens, most people go through the tedious trial and error method of trying to find the new optimal print speed, and usually base it off of the usual Default Printing Speed, and just hope it works. I have done that myself. Once I realized that the feed rate is the most critical element for print success versus print failure, I started calculating it manually, and then entering the appropriate Extrusion Width, Extrusion Multiplier, Primary Layer Height, and Default Printing Speed combinations to get the exact feed rate I need to ensure a good print. If you shift any of those numbers, you still need to be at or below your optimal feed rate. You can't exceed it. With Simplify3D hiding this detail, it makes it hard to know when you've overstepped the optimal feed rate.

I suggest adding this feature in this way. On the FFF Settings dialog in the Other tab in Simplify3D, include the following editable settings in the Speed section:

Default Feed Rate
Maximum Feed Rate

Both values are specified as mm³/s (cubic millimeters per second). Or mm³/min, if using minutes as your Speed Display Units.

If you adjust Extrusion Width, Extrusion Multiplier, Primary Layer Height, or Default Printing Speed, then the Default Feed Rate will be automatically updated accordingly. It is essentially these 4 values multiplied. If you change Default Feed Rate manually, then it updates Default Printing Speed accordingly, by calculating it from Default Feed Rate, Extrusion Width, Extrusion Multiplier, and Primary Layer Height. This way the user is always aware of the feed rate in use for a print job.

Maximum Feed Rate lets you set a limit for the print job. If you choose any combination that takes things above the Maximum Feed Rate, then Simplify3D will warn you and not allow you to press Prepare To Print without fixing your profile. That way you prevent yourself from accidentally printing something that is going to fail and possibly jam your printer.

I also suggest showing the default feed rate in the upper left hand corner of the G-code viewer, and also have an option to view the G-code by feed rate rather than print speed. It's far more useful to me actually. Knowing the feed rate will help you diagnose jamming problems.

For the advanced 3D printer operator, who changes nozzles, changes filament types, print temperatures, extrusion width, layer height, etc., on a regular basis, these settings will be extremely useful.

Posts: 32
Joined: Thu Aug 03, 2017 5:20 pm

Re: Default Feed Rate and Maximum Feed Rate

Sun Oct 11, 2020 5:55 pm

PrusaSlicer, SuperSlicer, and others already have a "Volumetric Flow Rate" feature that you can set for different materials. I'd give that a shot until S3D one day releases a version of software that might have it.

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