Orientation vs time to print

[shmbry]

I am experimenting with MC prior to getting my Rostock MAX V2. I have selected RostockMAX as the printer within MC and have been looking at the various settings and options. I have a solid block as a stl file measuring 10mm x 40mm x 90mm. I am getting different print times depending on the orientation;

With the block laying flat (90mm x axis by 40mm y axis) the print time is 49 minutes

with the block on its side (90mm x axis by 10mm y axis) the print time is 2hours 7 minutes

with the block upright (40mm x axis by 10mm y axis) the print time is 4 hours 30 minutes

These are all with the same settings.

can anyone explain the variance in the print time?

Many thanks

[Jimustanguitar]

To oversimplify it, the machine moves relatively quickly from side to side, and slowly from top to bottom. Generally, a part laid flat will print quicker than if it's standing upright.

The less layers you print, the quicker the job. Reduce the layer count by positioning and rotating the object, and you shave time off of the print.

[teoman]

With the same logic, printing multiple objects side by side takes less time than printing then one after the other.

When you print them all side by side, you can imagine it as many big layers and you have a flattish object whereas if you print one after the other it is like printing a tall object (parts stacked on top of each other).



Excluding setup time evidently.

[IMBoring25]

Jim's latter point is especially true if you have cooling enabled to avoid depositing on molten layers without running a part fan (per the general recommendation for ABS). If you have small enough layers that your selected minimum layer time drives the machine speed, print time will literally be proportional to number of layers.

[shmbry]

Many thanks for the replies. If this is the case does the slower travel / deposition in the z axis not negate, to a degree, the foot print vs height design of the MAX and other delta printers? Or do all 3D printers share this disparity in X,Y vs Z ?

[Jimustanguitar]

Its in all FDM printers. It's not the speed that the machine can travel in, it's in the way that the hot-end itself lays down plastic. For example, a .5mm nozzle is pretty standard, and the extrusion width is usually 10-20% wider than that because of die swell... So if you're printing layers that are .6mm wide and your layer height is set at .2mm (which is pretty standard), your layers are 3x wider than they are tall... That's why.

The other reason that z height can slow down a print, which was eluded to above, is that you can set a minimum layer time. Say 20 seconds or so. This is how long you determine the plastic needs to sit before it's cooled and solid enough to print a new layer on. Then you multiple that by the number of layers that you're printing, and it adds up quickly. With that example, 20 seconds times 5 layers per mm means that your print will take a minimum of 1:40 per mm in z height. Print a part that's 100mm tall, and you're talking about a long time.

The extrusion width vs height is what makes large parts take longer, and the minimum layer time is what makes smaller prints take longer.