100% fan for bridges/overhangs

[mrx23dot 0]

Hello,

 

What settings can I use to set the part cooling fan to 100% but only for bridges/overhangs?

 

On other layers I need it to be 0%, because PETG doesn't like cooling. 

[gr5 1,733]

I don't think this is in normal cura but it is DEFINITELY in the MB version of cura made by our own @burtoogle and I've used this feature many times - it's very useful for me when printing above 200mm/sec.  There are all kinds of bridge settings.

 

By the way, in either version of cura, once you have the advanced settings open, type "bridge" in the settings search box and it shows you things even if they are normally invisible.

 

Anyway here it is:

https://github.com/smartavionics/Cura/releases

 

Yeah it seems sketchy but I vouch for the guy.  I've met him in person.  Good guy.  His versions of cura are the version I use the most.  burtoogle is the same person as smartavionics on github.

 

[mrx23dot 0]

Thank you so much, I will try it out!

 

 

Bridge settings is already in mainline 4.7.1 under Experimental.

I hope we keep merging in his changes.

 

[paoletto 2]

Thanks for the useful info! I wish offy cura would at least offer cooling for overlaps among the settings -.-

[calinb 11]

I need a fan speed control behavior that's even simpler (and, as I recall, available in the original Cura as well as the netfabb engine).

 

I don't desire any kind of fan speed scaling from "Regular Fan Speed" to "Maximum Fan Speed." I honestly don't see any reason for this behavior, except maybe for printing pyramids or cones!

 

I simply want the fan at 0% speed or, upon reaching a minimum layer print time threshold, xx% speed--nothing in-between.

 

An even more advanced behavior would be for the fan speed to inversely scale with layer time, but not UNTIL reaching a "min-layer-time-before-fan-enable" threshold. Until reaching this min threshold, the fan is OFF.

 

I mostly print nylon. The only time I need a fan is when the layer area is very small that layers print very fast--even at minimum speed (usually set to 10mm/sec). Often times, this is when the print features suddenly "neck down" to a very small layer surface area.

 

I usually just hand edit the gcode and add a M106 SXXX command at the appropriate layer, but I really think Cura should handle this behavior!

 

It would also be nice if Cura's Preview layer numbers matched the layer numbers in the gcode. Cura Preview begins numbering with  layer "1" but the gcode it creates starts with "LAYER:0." When I forget about this inconsistency, my M106 hand edits end up being off by 1 or 2 (if I compensate in the wrong direction) layers. Doh!!!

 

 

 

[calinb 11]

Deleted--quote didn't work!

Edited April 11 by calinb

[calinb 11]

 

I'm downloading the smartavionics Cura. It's great to see ARM support too!

 

The README.md says:

* Initial Fan Speed At Height/Layer lets you specify the layer at which the initial fan speed comes into effect. Below that layer, the fans are off.

 

Woo-whoo! Thanks, gr5.

 

On 12/25/2020 at 7:44 AM, gr5 said:

I don't think this is in normal cura but it is DEFINITELY in the MB version of cura made by our own @burtoogle and I've used this feature many times - it's very useful for me when printing above 200mm/sec.  There are all kinds of bridge settings.

 

<snip>

 

 

 

 

 

[calinb 11]

Smartavionics fan control is buggy. I can't get it to do what I want it to do either (what it claims it can do with the "initial fan speed" feature). I'll just keep patching M106 statements into the gcode by hand. I could patch dozens if not hundreds of files in the time I've wasted on this.

Edited April 11 by calinb

[calinb 11]

I spent more time trying to make sense of fan control in the new Smartavionics Cura Master 20210420-3 release. As with the official UM Cura version documentation, I still don't think it works as advertised in the README.md file but I'd like to document a few useful settings and behaviors that I have discovered.

 

One behavior that must be always be considered in my following examples is "Regular Fan Speed" is always enforced at Layer 1 (layer 0 in the gcode) so, in many of the examples that follow, it must be zero to delay fan activation to a higher layer. I will explain other "Regular Fan Speed" effects in my examples, when pertinent.

 

In the following examples, I believe either "...at Height" or "...at Layer" may be used according to one's preference, but I used "at Layer" controls.

 

A Simple Constant Speed Cooling Fan "On" at Height Example:

 

50% fan speed will activate at layer 50 and gradually decrease to a "Regular Fan Speed" of 0% at layer 9999. "Regular Fan Speed" must therefore be set to an arbitrarily large number so the decrease is negligible to the last layer of the print. If "Regular Fan Speed" is set to 50% to match the desired speed, the fan will activate on layer 1 at 50%, which violates the README.md claim:

Quote

* Initial Fan Speed At Height/Layer lets you specify the layer at which the initial fan speed comes into effect. Below that layer, the fans are off.

 

Even though the "Regular/Maximum Fan Speed Threshold" is set to 0, "Maximum Fan Speed" must also be set to zero, else fast printing layers can affect fan speed, usually negligibly.

 

A Layer Time-Based Cooling Fan Example:

 

The fan will run at the "Regular/Maximum Fan Speed Threshold" and scale inversely with layer time between 0% and 100%.  "Regular Fan Speed" must remain zero to avoid fan activation at and after layer 1. "Initial Fan Speed at Layer" is a don't care, because "Initial Fan Speed is set to zero."

 

A Layer Time-Based + On at Height Cooling Fan Example:

 

Layer-time control has precedence over "at Height" control so Layer-time will override (reduce or increase) "at Height" control when the "Regular/Maximum Fan Speed Threshold" is satisfied. In this example, Layer-time control will vary fan speed inversely with layer time between 0% and 100%. If the "Regular/Maximum Fan Speed Threshold" is not met, the fan will run at 50% anytime after layer 50 in this example.

 

A Simple Constant Speed Cooling Fan "Off" at Height Example:

 

The result is 75% fan on at layer 1 and fan off at layer 10. "Regular Fan Speed at Height" must, again, be set arbitrarily large, because the fan increases to "Regular Fan Speed" after layer 10. Setting the value to be very large keeps the fan nearly off (insufficient enough voltage to even spin the fan, which should not be harmful to the fan).

 

There are plenty of other examples, but the above set is a good start and covers nearly all that I need from fan control. I think two, usually helpful, rules to keep in mind are:

 

1. If "Regular Fan Speed" is non-zero, the fan will receive power at layer 1.

 

2. Unless a layer time component of fan speed control is desired, set "Regular/Maximum Fan Speed Threshold" to zero and set "Maximum Fan Speed" to the value of "Regular Fan Speed." (Cura does not permit "Maximum Fan Speed" to be less than "Regular Fan Speed.")

 

Some the above should be useful with UM Cura too (though UM Cura lacks the "Intitial Fan Speed at Height / Layer" settings), but now I need to go check if I can get any good results from UM Cura.

 

I think both versions have a long way to go before they become intuitive--at least for me! 😞

 

P.S. Please ignore the following screen capture. I delete it but it keeps coming back and I can't figure out how to remove it from my uploaded images but I figured out how to turn it into a linked image.

 

ignore_this_image

Edited May 4 by calinb

[calinb 11]

I still can't do anything with UM Cura fan control but run a fan from layer 1, which isn't very useful with the nylons I usually  print.

 

Using Smartavionics Cura Master 20210420-3, I get layer time based fan speed control with the following settings. Only the fastest printing layers receive fan cooling (up to 100% for the very quickest ones).

 

 

Essentially the same settings in UM Cura 4.9.0 barely powers up the fan (not enough to spin it) for much lower layers on the same model, which are not the fastest printing ones and don't need any fan. I tried other settings but I still can't get the UM version to behave in a useful way.