Time remaining

[mark-hale 1]

Have noticed that the time remaining, displayed on the Ultimaker2 seems to vary a great deal compared to CURA.

Was printing an item last night, which on CURA said 15mins, but on starting this on the UM2, the display showed 2 hours, this time fluctuated quite a bit and only seemed to be accurate in the last several minutes. It did actually only take 15 minutes so assume its a calibration issue.

Where does the printer get it's time estimates from, is this something that the end user can adjust.

 

[IRobertI 520]

I haven't read through the firmware so I don't know but I'm guessing it's a simple estimation calculated based on how long the already printed layers took to print (average) * how many layers are left. That's why the estimate gets more accurate towards the end of the print. Cura probably does a more advanced calculation where it actually goes through and estimates the time for every layer all at once.

 

[Daid 306]

The estimate on the screen is a bit of a complex piece of code, and it depends a bit on the GCode file. If you have the UM2 profile, then the UM2 will show the time estimate from Cura in the LCD panel before selecting the file.

First, it calculates how long it has been printing already. Next, it takes how far it is in the GCode file, and how long the file is. With this it calculates the total time estimate for how long the print will take.

When it has Cura estimate, it will look at how long it has been printing already, if this is less then half the time of the estimate, then it will use this estimate combined with the estimate from the "how far is the print" estimate. And depending on how far it is with printing the more the final estimate will shift towards the estimate from the actual printing time.

Or, in pseudo code:

 

printTime = [Time spend printing so far]
filePosition = [current read position in the gcode file]
fileSize = [total file size of the gcode file]
timeEstimateFromCura = [Time estimate from Cura, if in GCode file]
totalPrintTimeEstimate = printTime / filePosition * fileSize
if printTime < timeEstimateFromCura / 2:
  f = printTime / (timeEstimateFromCura / 2)
  finalEstimate = totalPrintTimeEstimate * f + timeEstimateFromCura * (1.0 - f)
else:
  finalEstimate = totalPrintTimeEstimate

The "estimate by print time" is off for the first few layers because it's printing slower, so it's not that accurate at the beginning. The CuraEstimate is off due to it not accounting for acceleration.

(There is also some odd overflow bug, that causes the display to jump to 6 hours sometimes)

 

[mark-hale 1]

many thanks for the explanation. Yes funny you should mention the bug, I did notice that at one point.

So far the figures in CURA seem close enough to help me decide to either wait for the print to finish or go to bed :grin:

 

[nkuck 0]

I'm running a Prusa i3 model and can see the overall time, but nowhere do I see a remaining time. Is it somewhere hidden?

[geert_2 557]

In my UM2 (non-plus) with original firmware, the calculation goes wrong when the tune-menu is kept open. For example when manually adjusting temp. If this tune-menu has been open for some time, then the remaining time sometimes increases to hours extra (on a print of a few hours). It looks like the calculation is paused or so? After the tune-menu has been closed, remaining time slowly recovers to reasonable values. But I don't care, since it doesn't affect print quality.