Comments on (sorta) high volume FDM printing
Posted: Wed Nov 04, 2015 5:34 am
A primary reason why I purchased my M2 is because of its relatively large print bed. The initial task for the printer involves printing a relatively large number of pieces (about 500). These pieces fit 4 up on the M2 platen.
Printing 4 up does not increase print speed, but it does improve printer utilization and therefore thruput. For example, if I start a print last thing in the evening, 4 up gives me four pieces overnight, whereas 1 up yields only one.
I've now learned that taking an object that prints well at 1 up to 4 up is not so straightforward. The basic problem is the extruder doesn't behave well through extrusion stop/start. When printing 4 up, there are usually many extrusion stop/starts between pieces. And the duration of these stop/start cycles is relatively long.
The extrusion process is dynamic. When extruding continuously, an equilibrium is achieved in the extruder and this gives a uniform bead.
Retraction is a technique for synchronizing extruder equilibrium with extruder movement. My experiments with retraction so far have not been very successful. It seems like the slicer needs to drive the extruder material and extruder displacement such that a uniform bead is achieved. I use slicr3r. Its retraction algorithm doesn't seem to think this way. Perhaps other slicers are more better?
I've had good success when I am able to coerce my object such that it looks like a single piece (no stop/start) to the extruder. But alas, this is not always possible.
Without having any practical knowledge of FDM printing, I had assumed I could simply squirt molten plastic wherever I wanted it. For the most part these objects I'm printing are well suited to FDM. But for my use model (4 up), the difficulties around extruder stop/start turn out to be a major and unexpected consideration.
I don't have any answers, but perhaps reporting my experience will help others.
bignordique
Printing 4 up does not increase print speed, but it does improve printer utilization and therefore thruput. For example, if I start a print last thing in the evening, 4 up gives me four pieces overnight, whereas 1 up yields only one.
I've now learned that taking an object that prints well at 1 up to 4 up is not so straightforward. The basic problem is the extruder doesn't behave well through extrusion stop/start. When printing 4 up, there are usually many extrusion stop/starts between pieces. And the duration of these stop/start cycles is relatively long.
The extrusion process is dynamic. When extruding continuously, an equilibrium is achieved in the extruder and this gives a uniform bead.
Retraction is a technique for synchronizing extruder equilibrium with extruder movement. My experiments with retraction so far have not been very successful. It seems like the slicer needs to drive the extruder material and extruder displacement such that a uniform bead is achieved. I use slicr3r. Its retraction algorithm doesn't seem to think this way. Perhaps other slicers are more better?
I've had good success when I am able to coerce my object such that it looks like a single piece (no stop/start) to the extruder. But alas, this is not always possible.
Without having any practical knowledge of FDM printing, I had assumed I could simply squirt molten plastic wherever I wanted it. For the most part these objects I'm printing are well suited to FDM. But for my use model (4 up), the difficulties around extruder stop/start turn out to be a major and unexpected consideration.
I don't have any answers, but perhaps reporting my experience will help others.
bignordique