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BaronWilliams
Posts: 159
Joined: Tue Jul 15, 2014 8:30 pm

Default Feed Rate and Maximum Feed Rate

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.

User avatar
BaronWilliams
Posts: 159
Joined: Tue Jul 15, 2014 8:30 pm

Re: Default Feed Rate and Maximum Feed Rate

Wed Mar 23, 2016 1:50 am

One of the main causes of a 3D printer jam is exceeding your 3D printer's feed rate.

Most 3D printers cannot print ABS faster than about 13.50mm³/s using a 0.40mm nozzle. Filament manufacturers should tell you this. But instead they give mm/s speed recommendations, which is nearly useless. If your printer can print ABS at 13.50mm³/s, like mine can, then that's what your printer settings should be based off of. Every setting should stem from that. Some printers can print ABS a little faster, some a little slower. If you know your feed rate, and don't exceed it, then you can adjust layer height, extrusion width, print speed, etc., and never worry about your printer exceeding the feed rate, clicking from it, and jamming from it.

The maximum feed rate for a particular filament on a particular printer is a constant value. Being able to set a limit for the feed rate is something you only need to do 1 time for a given filament, and a given printer configuration. It doesn't change, unless you change filament type, or change printers, or change your printer configuration. However, with Simplify3D, changing extrusion width, extrusion multiplier, layer height, print speed, etc., all change the feed rate, and unfortunately Simlify3D gives you no indication of the feed rate it will use based on all these settings. You need to calculate this on your own to know if you've exceeded your printer's feed rate for the filament you're using. I have a spreadsheet that I use for this now.

Here's a photo of a spreadsheet I use to calculate the proper maximum print speed at different extrusion widths and layer heights, to ensure that I don't exceed my printer's feed rate for ABS, which is the typical 13.50mm³/s on my printer when using a 0.4mm nozzle. I use this spreadsheet all the time. As long as I follow this, MY PRINTER WILL NEVER CLICK. I don't worry about exceeding my feed rate, as long as I use this spreadsheet.
PrintingSpeeds.jpg
Simplify3D should automatically prevent me from exceeding my printer's feed rate. I should not need my own spreadsheet for this. If we had Default Feed Rate and Maximum Feed Rate settings as I proposed above in my initial request, I could delete this spreadsheet and never look at it again. Boy would that be awesome.
Last edited by BaronWilliams on Mon Mar 28, 2016 4:21 am, edited 1 time in total.

mroek
Posts: 146
Joined: Mon Oct 26, 2015 1:47 pm

Re: Default Feed Rate and Maximum Feed Rate

Wed Mar 23, 2016 7:28 am

+∞

In other words, I could not agree any more. It would have been absolutely awesome if S3D would implement this, as the first slicer (that I know of) to get this right. And it really isn't difficult to implement either, so no real reason for them not to do it.

inventabuild
Posts: 80
Joined: Sat Mar 19, 2016 12:29 pm

Re: Default Feed Rate and Maximum Feed Rate

Sat Mar 26, 2016 12:46 am

+1
Feed Rate does seem like it would be a useful tool to prevent someone from unwittingly trying a setting that causes a hot end jam. S3D already has this information so why not let print masters use it to their advantage?

User avatar
BaronWilliams
Posts: 159
Joined: Tue Jul 15, 2014 8:30 pm

Re: Default Feed Rate and Maximum Feed Rate

Mon Mar 28, 2016 4:55 am

I am printing today and using different layer heights and extrusion widths for different transparency effects using clear PETG. Transparency is greatly increased if you use larger extrusion widths and larger layer heights, and larger nozzles. If you push your largest nozzle to the limits, you can get some really nice clarity from PETG. Using a 0.6mm nozzle I was able to get an extrusion with of 2.0mm and a layer height of 0.5mm, just as long as I didn't exceed an extrusion feed rate of 9.38mm³/s, which calculates out to using a print speed of 9.4mm/s.

For the novice, doing these kinds of adjustments tends to cause printer jams, because it's so easy to go above the maximum extruder feed rate for PETG, since it melts slower than PLA or ABS. A novice is typically not aware of extruder feed rates, despite it being the single most important setting you can ever use for a successful print, because slicers wrongfully hide this from users.

For PETG, on my printer with a 0.6mm nozzle, I get a maximum extruder feed rate of about 9.38mm³/s. Using my spread sheet, I have pre-calculated feed rates for PETG, ABS, etc., so I know exactly what combination of Extrusion Width, Primary Layer Height, and Default Printing Speed settings I can use without exceeding 9.38mm³/s for my 0.6mm nozzle.

On a FlashForge Dreamer 3D printer using the 0.4mm nozzle it comes with, I calculated that ABS has a maximum extruder feed rate of about 13.50mm³/s. PETG's maximum feed rate is about 8.44mm³/s for a 0.4mm nozzle. It would be great if the Simplify3D FlashForge Dreamer profiles had this information. When you select ABS, it should by default use a Maximum Feed Rate value of 13.50mm³/s. When you select PETG, it should by default use a Maximum Feed Rate value of 8.44mm³/s. Of course it should let you customize these settings.

Each default printer profile should have Maximum Feed Rate information stored for each filament type.

For a novice, wouldn't it be great if you could adjust the layer height, extruder width, etc., and not worry about a printer jam from exceeding the extruder's feed rate? No one likes to deal with a jammed printer. By having such settings, we greatly limit the possibility of jamming our printers when we fiddle with settings.

By adding both Maximum Feed Rate and Default Feed Rate settings to default printer profiles, Simply3D would greatly reduce the number of printer jams it's users report. I think that's a big plus.

KC_703
Posts: 238
Joined: Tue Aug 26, 2014 5:23 pm

Re: Default Feed Rate and Maximum Feed Rate

Sat Apr 02, 2016 4:43 pm

I mixed feelings about this...

While it would be good to know the default calculated feed rate. I think becuase its a combination of all the settings mentioned, an "override" could be detrimental.

Rather than considering all the parameters above, why not just focus on one. For instance the multiplier is a good parameter to adjust for control of feed rate. Using more than one increases the control, but increases the complexity.

armstrongc02
Posts: 3
Joined: Sat May 21, 2016 11:02 am

Re: Default Feed Rate and Maximum Feed Rate

Thu Jul 07, 2016 2:09 pm

BaronWilliams wrote:One of the main causes of a 3D printer jam is exceeding your 3D printer's feed rate.

Most 3D printers cannot print ABS faster than about 13.50mm³/s using a 0.40mm nozzle. Filament manufacturers should tell you this. But instead they give mm/s speed recommendations, which is nearly useless. If your printer can print ABS at 13.50mm³/s, like mine can, then that's what your printer settings should be based off of. Every setting should stem from that. Some printers can print ABS a little faster, some a little slower. If you know your feed rate, and don't exceed it, then you can adjust layer height, extrusion width, print speed, etc., and never worry about your printer exceeding the feed rate, clicking from it, and jamming from it.

The maximum feed rate for a particular filament on a particular printer is a constant value. Being able to set a limit for the feed rate is something you only need to do 1 time for a given filament, and a given printer configuration. It doesn't change, unless you change filament type, or change printers, or change your printer configuration. However, with Simplify3D, changing extrusion width, extrusion multiplier, layer height, print speed, etc., all change the feed rate, and unfortunately Simlify3D gives you no indication of the feed rate it will use based on all these settings. You need to calculate this on your own to know if you've exceeded your printer's feed rate for the filament you're using. I have a spreadsheet that I use for this now.

Here's a photo of a spreadsheet I use to calculate the proper maximum print speed at different extrusion widths and layer heights, to ensure that I don't exceed my printer's feed rate for ABS, which is the typical 13.50mm³/s on my printer when using a 0.4mm nozzle. I use this spreadsheet all the time. As long as I follow this, MY PRINTER WILL NEVER CLICK. I don't worry about exceeding my feed rate, as long as I use this spreadsheet.
PrintingSpeeds.jpg
Simplify3D should automatically prevent me from exceeding my printer's feed rate. I should not need my own spreadsheet for this. If we had Default Feed Rate and Maximum Feed Rate settings as I proposed above in my initial request, I could delete this spreadsheet and never look at it again. Boy would that be awesome.
Can you give me some insight as to how you came up with this spreadsheet? I'm having a hell of a time getting my Airwolf Axiom tuned right with a nozzle smaller/larger than the .5 mm default. It grinds and crunches with smaller nozzles, and sputters with larger ones when I use Simplify (in Cura I just adjust the flow rate and that seems to work well). I appreciate any help!

CptanPanic
Posts: 3
Joined: Fri Jul 10, 2015 9:52 am

Re: Default Feed Rate and Maximum Feed Rate

Wed Aug 24, 2016 10:35 am

Any updates to this? I would like to have this feature also. Would like to be able to limit max feedrate, or at least see what the calculated one is.

adams3463
Posts: 3
Joined: Thu May 22, 2014 12:29 pm

Re: Default Feed Rate and Maximum Feed Rate

Tue Jan 03, 2017 10:24 am

I agree this is very important also and would like to see this feature added. I would also like to add yet a further nuance regarding feed rate which is that the lower limit is just as important as the upper limit. Most people seem to be focused on how fast they can extrude, but when printing small parts at 100um resolution or less, I believe there is also a minimum extrusion speed that becomes a factor as well. This has to do with feed rates that are slow enough to allow the filament to dwell too long in the melt zone resulting in the glass transition point traveling farther up the filament, resulting in softening and eventually jamming because the filament is no longer stiff enough to resist the nozzle counter pressure. To correct this, you might say just lower the temperature of the hotend, which is an option within a certain window of factors, but lowering the temp also increases nozzle counter pressure, therefor at some point it becomes difficult to balance the extrusion speed with all of the other factors. Not to say that it can't be done, it is just much more difficult to do so without the ability to set the extrusion speed directly.

CompoundCarl
Posts: 2005
Joined: Wed Aug 05, 2015 7:23 am

Re: Default Feed Rate and Maximum Feed Rate

Wed Jan 04, 2017 5:08 am

adams3463 wrote:I believe there is also a minimum extrusion speed that becomes a factor as well
I control this already using the options on the cooling tab. That allows you to set the minimum speed so that it will only slow down to say 20% at most even when printing tiny parts. That's how I control the min printing speed right now.

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