Hi all, I`m doing a project where I am attempting to 3D print large objects with a relatively simple geometry at high speeds. The idea is that the printed geometry will act as a mold for a final product and the objects I want to create will be about 0.2x0.2x1m (and preferably up to 1,5-2m in a later stage).


Because I`m working at a scale like that and with simple geometry (extruded triangles, squares and circles without any infill, just the outline) surface quality/finish is not very important to me, however strength and proper layer adhesion is.


The material I am using is PLA, 1.75mm and instead of having a traditional 3D printer I have mounted a Flexion extruder on a robot arm. The advantages of this is that I am relatively unconstrained in size, however the drawback is I am more limited in the use of 3D print software etc. as I am custom controlling it using Rhino 3D and an Arduino independently. Also I am not using a heated bed.


I have been doing many tests to see what the maximum speed I can achieve is but this is where I am having issues. With my 0.5mm nozzle and a layer height of 0.38mm the maximum speed I can reach while still having a reasonable surface finish (only some minor layer delamination) is 75 mm/s. Beyond this speed or above this layer height the layer adhesion starts to become such a problem that the objects are not stable anymore. I also drilled out another nozzle with a 1mm drill to see if using a larger nozzle I could improve my printing speed. I hoped to be able to multiply my speed by about 1.5x because of the thicker layers I can use, however this is not really the case. With the 1mm nozzle (probably it is a bit bigger even, 1.1 or 1.2mm I can go up to a layer thickness of 0.7mm, however in order for the layers to properly stick together I also have to decrease the speed to about 30 mm/s. This means actually it is even slower than printing with a smaller nozzle because of the extremely reduced speed.

Ideally I would like to achieve a combination of a layer height of 0.5mm and a speed of 100 mm/s or a layer height of 1mm with a speed of 50 mm/s using a larger nozzle. Even faster would be even better but for now this is a reasonable aim. Do you have any ideas on how to achieve those rates? I was thinking of perhaps switching to 3mm filament so I could use a 2mm nozzle and greatly increase my layer thickness. However this would require me to remodel the entire tool mounted to my robot arm because the extruder I am using does not support the bigger filament. That`s why before making this decision I would like to be sure that it would improve my speeds.


What are your thoughts? Any advice on large scale, high speed, low resolution printing? Should I try other materials? Other types of tools? Any advice is greatly appreciated!