Variable Layer Height greatly increases print time  

RE:

Not sure the feature was ment to decrease print time. It was just a way to automatically get more layers where needed which would INCREASE the time.

In the case of this model, because its so complex, I suspect reducing to very thin layers at detailed areas, hence the increase in time.

I never saw this as a say to speed anything up.. for me I use it when I want thinner layers at key points of the print without adding too much time to the print.

That said, i guess you could say that it does give an improvement in speed if you think of the feature another way.

Say for example you have an object sliced at 0.2mm and this has a print time of 1 hour. and then the same object at 0.1mm with a print time of 2 hours.. By using VLH, you can print the important bits at 0.1mm and the rest at 0.2mm giving you higher quality, without printing the whole thing at 0.1mm.. But the amount of extra time is all down to how detailed the model is and now many layers get printed at higher resolution..

RE: Variable Layer Height greatly increases print time

Great information... I have only used variable layer height to get better detail. If I use it to increase layer height from 0.20 QUALITY to 0.30, is the quality the same as 0.20 or is it more like 0.30 DRAFT, or somewhere in between?

RE: Variable Layer Height greatly increases print time

If the layer is made 0.3 using VLH then its the same as 0.3 draft for those sections.  The only resolution in question is vertical, the x/y details remain unchanged as the extrusion width remains the same regardless of printing at 0.3 or even 0.1.  If you have a straight sided wall like a box for example them a 0.3 can look better and it prints faster.  

RE: Variable Layer Height greatly increases print time

thanks, great information. I assumed my layer height setting was the 'minimum' height that would be used. is there a way to restrict the minimum layer height for VLH? I don't see any setting that would do this

Posted by: @joantabb

Variable layer height can be used to make layers thinner when more vertical detail is required, and make layers thicker when less vertical detail is required

If you only use variable layer height to make layers thinner, then the print time will go up, 
If you only use variable layer height to make layers thicker then the print time will go down
if you use variable layer height to both make layers thicker where detail is minor, and thinner where detail is greater the print time will depend upon the percentages of layer heights compared to the standard layer height for that profile

If you print Kratos Bust at 0.2mm  quality layer height the print time will be in the region of  8 hours 57 minutes
If you print Kratos Bust at 0.2mm layer height  and use variable print height to smooth his shoulder tops and head, the print time will be in the region of  11 hours 7 minutes
If you print Kratos Bust at 0.2mm layer height  and use variable layer height to print the supports quickly and smooth shoulder and head the print time will be in the region of  10 hours 9 minutes
If you print the whole Kratos Bust at 0.07mm layer height the print time will be in the region of 1 day 3 hours and 15 minutes

so as you can see variable layer height is faster than using a small layer height for the entire model, but slower than using 0.2mm quality for the whole model

If however you printed the same bust with an SL1s, and 0.05mm layer height, the print time would be in the order of 2 hours 4 minutes. (note I didn't modify the model to have drain holes)  it's a hollow object so without drain and vent holes the inner chamber would remain full of resin)

regards Joan

RE: Variable Layer Height greatly increases print time

There is but it’s not in an obvious place. It’s in Printer Settings>extruder. The vlh uses the minimum height value configured in there, and also the max too.