Increase Print Time Estimate Accuracy?

[DaHai8 68]

I was wondering if there was something I could do to increase the accuracy of the print time estimate after slicing.

In both v15.x and 2.1x, the current estimates are around 20%-25% under. In other words, if Cura estimates a 8hr print, it will take closer to 10hrs. For a 1hr estimate, its usually takes 1hr 15 mins.

Maybe this is just an artifact of a non-Makerbot printer or its firmware specific. I read some previous posts from a few years back about acceleration factors. So maybe there is a tweek I can add to a parameter in Cura (15.x or 2.x) to take this into account and narrow this delta a bit?

Wondering if anyone else is seeing this delta or if its just me and my printer.

Thanks!!!

[Dim3nsioneer 446]

Difficult as Cura doesn't know about acceleration, jerk and maybe retraction settings of your printer.

[gr5 1,134]

Cura used to always be inaccurate in predictions but then they included most of the marlin planner mechanism into the planning and now it's spot on - around 1% error. But they used the acceleration and jerk settings for a typical Ultimaker and even Ultimaker people mess with that. Ultimaker is 25% faster at the speeds you print (because of the higher acceleration). So one solution is to buy an ultimaker.

[DaHai8 68]

Thanks guys! I didn't think there was much that could be done, but thought I'd ask.

I'll save my pennies.

Cura 2.x beta and 15.x are still excellent slicers as this is just a minor thingy.

Cheers.

[DaHai8 68]

I'm guessing there is no where in Cura to set the Acceleration, Jerk and Retraction settings of my printer?

[DaHai8 68]

Found the fdmprinter.def.json file on GitHub and have been trying to insert the Acceleration and Jerk settings for about 3 hours last night before giving up. I thought maybe they weren't implemented yet, but then saw this post:

https://github.com/Ultimaker/Cura/issues/798

Clearly, I'm doing something wrong. Any help on this would be greatly appreciated:

 

"speed": {       "acceleration_enabled": {           "label": "Enable Acceleration Control",           "description": "Enables adjusting the print head acceleration. Increasing the accelerations can reduce printing time at the cost of print quality.",           "type": "bool",           "default": false,           "settable_per_mesh": false,           "settable_per_extruder": false       },       "acceleration_print": {           "label": "Print Acceleration",           "description": "The acceleration with which printing happens.",           "unit": "mm/s²",           "type": "float",           "min_value": "0.1",           "max_value_warning": "10000",           "default": "300",           "enabled": "acceleration_enabled",           "settable_per_mesh": true       }   }

 

Edited June 13, 2016 by Guest

[DaHai8 68]

Update: While defined in fdmprinter.def.json, a superscript of 2 in "unit": "mm/s²", of acceleration_print is not like by Cura. removing the 2, allowed the .json file to load.

Now to see if it actually impacts print time estimates....

[DaHai8 68]

And that would be a big "NO". No effect. I guess I'm back to: It's defined but not yet implemented. bummer...

[nallath 623]

Did you use the lastest version of the engine? You are using nightly builds (which do work for me, but you might not have updated everything)

[DaHai8 68]

Na, I was just using the 2.1.2 release.

I'll dig into the nightly builds - wasn't sure if I should go there.

Thanks!

[gr5 1,134]

 

@nallath - is this parameter highlighted above simply sent as a gcode at the start of the print? Or is it used only to estimate print times? Or is it used for both things?

[nallath 623]

The nightlies of Cura can have jerk & acceleration set per "feature" (Infill, walls, roofs, etc). But some of the stuff might be on a branch, hence my comment.

[gr5 1,134]

The nightlies of Cura can have jerk & acceleration set per "feature"

Very cool but that doesn't answer my question.  Are these accelerations used to calculate the print time or is print time calculation not configurable (hardcoded)?

[nallath 623]

I'm not sure what is done. I do know that it should be taken into account.