Overhanging Wall Speed Request

[Safety_Lucas 0]

I have had some great success with the experimental "Overhanging Wall Speed" and "Overhanging Wall Angle" features, printing unsupported walls at up to 70° without sagging! I would like a feature where the speed scalar is a function of the overhang angle, rather than a constant value that activates at some threshold angle as it is now. The effect would be that the speed at which overhanging walls are printed varies according to how steep the overhang is. 

[burtoogle 508]

Hello @Safety_Lucas, thanks for the interesting report. Can you provide more info, please? What range of speeds would you want to use WRT the overhang angle?

 

BTW, my Cura builds also provide a separate fan speed setting for overhanging walls:

 

 

That feature has already been rejected by the Cura developers so it's only going to be available in my builds (Linux and Windows only, I'm afraid) which can always be found at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0

[yellowshark 153]

Very impressive @Safety_Lucas. What size fount did you use?

[Safety_Lucas 0]

10 hours ago, burtoogle said:

What range of speeds would you want to use WRT the overhang angle?

@Burtoogle, Thank you for the link. I will take a look at those distributions Do you make them yourself? As in, do you write the code for Cura features? The setting is presently handled by multiplying the overall print speed by some decimal amount. I typically print at 40mm/s and scale the overhanging wall speed by 0.25. Overhangs are thus printed at 10mm/s. But I have experimented with higher and lower values from 5mm/s to 15mm/s with predictable results. I would prefer the feature be a function of overhang angle rather than a range of values though as different materials, temperatures, flow rates, etc. will require different reduced speeds to print the same overhang angle. I suspect an appropriate equation for such a feature would not be a simple straight line scale from 0 to 90° but rather would slow the print speed more severely at extreme angles and less severely at shallower angles. Like a scaled e^x sort of curve. 

[burtoogle 508]

2 hours ago, Safety_Lucas said:

Thank you for the link. I will take a look at those distributions Do you make them yourself? As in, do you write the code for Cura features?

 

Yes, I make them myself and they are based on Ultimaker's development sources + my own fixes and additions.

 

OK, I'll think about the speed factor. Maybe something based on the tan of the overhang angle would be good?

[Safety_Lucas 0]

I'll run some experiments this weekend to come up with some good maximum speeds for various extreme angles. An equation can be made to model that data.

[usshadowop 0]

Not related to the request but what speed did you print at for your tests in the photo?

[usshadowop 0]

Also what fan speed?

Edited July 6, 2019 by usshadowop
accidental double post

[Safety_Lucas 0]

@usshadowop The bulk of the print was at 20 mm/s but walls overhanging 30 degrees or more were scaled by 0.25. So 5 mm/s for the overhangs. The fan speed was 100% all the way through.

Edited July 6, 2019 by Safety_Lucas

[Johnn 2]

Good stuff ! Overhangs are such a pain, I hope it will be in the official release soon.

[LeckieInstalls 0]

On 6/26/2019 at 1:07 PM, burtoogle said:

Hello @Safety_Lucas, thanks for the interesting report. Can you provide more info, please? What range of speeds would you want to use WRT the overhang angle?

 

BTW, my Cura builds also provide a separate fan speed setting for overhanging walls:

 

 

That feature has already been rejected by the Cura developers so it's only going to be available in my builds (Linux and Windows only, I'm afraid) which can always be found at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0

Is there any version of cura for mac that supports "Overhang wall fan speed"? This is absolutely essential for PTGE! 

[burtoogle 508]

3 hours ago, LeckieInstalls said:

Is there any version of cura for mac that supports "Overhang wall fan speed"? This is absolutely essential for PTGE! 

 

Yes, the macos builds that you can find at https://www.dropbox.com/sh/s43vqzmi4d2bqe2/AAADdYdSu9iwcKa0Knqgurm4a?dl=0 have that setting. Please read the README.md file there.

[geert_2 556]

That overhang is very impressive, indeed.

 

And what is the effect of this setting on the "curling up" tendency of steep overhangs? Where the edges bend upwards instead of sagging, causing the nozzle to bang hard into them, and causing vibrations and ugglyness too? And in extreme cases knocking the model off the bed?

 

See these tests.

 

 

 

 

 

 

[brunoosti 6]

Reviving this topic:

I think this feature should be a fixed velocity, and not a % of the inner/outer walls.

Some (like me) may want to print inner walls at 80mm/s and outer at 30, and set all overhanging walls to 20mm/s. This could be very useful and make cura a lot more capable. 

Another thing I noticed is that cura does not tell apart overhangs from bridge walls very well, changing velocities if you do not have everything set to the same speed (lets say 30mm/s normal wall speed at 70% for overhang wall (=21mm/s), and 20mm/s for bridge walls. 

See below how the first inner wall changes from green to blue, when it should be only green (as my inner walls are set to a higher speed). To work absolutely well this wall should be all blue (20mm/s), as it overhangs, but as my inner walls are set to 80mm/s, I can't slow them that much based on a %.