Well I can't fix it but I think I know how YOU guys can fix it :-)
I have a 200mm print going right now. S3D says 7 hours. its been over 7 hours and I am at 28% so estimating actual print time of 30hrs or so.
I think I know WHY its so "off"
jerk and acceleration. I don't think S3D is calculating jerk and acceleration properly into the equation AND I am pretty sure its not accounting for my Start Code script where I alter the Jerk and Acceleration with M205 commands.
basically the less "turns and changes" the print has the more accurate simplify 3d seems to be form me.
the current print I am making (the happy pilot gcode file is 83mb!!) with no infill 4 perimeters. but the "surface" detail on the model is simply ridiculous!
I set my Jerk to X5 and my acceleration to P500 T1000
so I Have these lines in my start script
M204 P500 T1000
I don't think this is being factored into the print time estimate calculations.
ALSO some of these machines have firmware hard ceilings (values they won't go beyond)
for example on older creality machines (not sure about newer) Retraction speed for the extruder was hard set at 25mm/s no matter how high a value I put in the slicer it was going to be 25mm/s
same with movement speed. my flashforge guider II appears to be hard set for travel speed at around 80-100mm/s
I set it for 150mm/s no change in print speed which made the slicer prediction that much more inaccurate.
SO for a partial fix end users can try and find out what they maxes are and do not program higher than that in the slicer (which will make it more accurate)
but you guys might also need to account for manual jerk and acceleration settings. OR have an entry box where we can specify these values so they are calculated properly in your print time estimations math.
it would also be nice if I COULD in fact enter these values for jerk and acceleration and S3D inputs the M205 and M204 commands itself and of course accounts for them in its calculations. even let me CHANGE it for different processes ie big round circles high acceleration and jerk. sharp corners LOW jerk and acc etc..
I can't upload a Factory file. its too large but its easy enough to make
scale to 195mm tall. 3 bottoms 3 tops 4 perimeters 0 infill 60mm/s 80% under 30% first layer under.
slicer predicts something around 7 hrs.
actual print time estimate based on current status of ongoing print 28-32 hrs. now higher up the model there are fewer "fine details" for it to apply jerk and acceleration changes too so it might actually end up faster but I doubt less than 20hrs. we shall see in 14-20 hrs :-)
Two Tree Sapphire S 200mm cubed core xy machine 0.4mm nozzle.
gcode analyzer is telling me 15hrs. we shall see. either way we are past S3D's prediction and only at 28%