S3D Print Time not Correct

[Alloy]

Has anyone else noticed prints taking longer than the stated build time in the preview? Setup a print last night and S3D stated it would take ~11H 43M to complete. Woke up this morning to find it still had 43 minutes to go. When it was complete the total run time as stated in the control was 1012 minutes, OVER 16 HOURS! I know the build time does not include warm up but it didn't take 4 hours to warm up. I am also thinking the build time estimator does not include raft build time...

[Jules]

Correct.

[Alloy]

Why not? It shows the raft in the preview, why cant it include the build time of it...

[Tim]

The actual timing of events is handled by the printer firmware, and S3D does not make any assumptions about what kind of firmware your printer has, and so it does not attempt to run through the detailed calculations. Instead, it just uses the maximum allowed speeds specified in the slicer setup, and maybe also does some guessing about the acceleration and deceleration. Because of that, you'll find S3D's guesses are closer for prints that have a lot of long, straight runs, where the print head can run at maximum speed for most of the print. For prints with a lot of short moves, the guesses get a lot worse. I think S3D's guessing was improved in some 2.X update, because early on, I found that the actual print time tended to be 50% to 100% longer than predicted, while recently it is more like 0% to 50% longer (although that's non-scientific, anecdotal evidence, and should be taken with a grain of salt). In my recent experience, the typical case is that the print takes close to 50% longer than predicted by S3D, which is close to what you got.

[Jules]

No, i meant "correct that the times are wrong", raft or no. Welcome to the club!

(Tim's right, just plan on S3D guessing the total time at about 2/3 of the actual time.)

[Alloy]

Thanks for explaining.

[Alloy]

and the reason I thought the raft was not included was I did not see the timer in the MCP start counting down until after the raft was complete

[Tim]

I just ran S3D with a tiny object scaled down to one layer. For the object by itself, S3D reports a build time of 1 minute. I then added a raft, and S3D reports a build time of 5 minutes. So it does include the build time of the raft. The time difference you see is just adding up bit by bit over the whole print.

[Matt_Sharkey]

my print time estimates come from pronterface, and when I see the estimate, I just double it. for the same reasons stated above. The gcode demands that your printer makes a specific move, and then the firmware calculates how to make that move, making estimates a crapshoot.

Now it would be nice if you could clone your firmware to your slicer software and it emulate a print to figure out the time...but maybe were just not there yet.

[Alloy]

Food for thought: Today I am watching the timer in the machine control panel and decided to time how long it takes for 1 "minute" to count off the clock. It is consistently taking 3:54 for 1 "minute" to go by. It would be interesting to see if this ratio is constant through the whole print...Ill keep you posted (if I remember to time it )