How Model Geometry Can Be Used To Print Even Bigger
In Update 28, we listed the build volumes for different configurations of nozzles. For a printer with 5 nozzles, printing in 5 colors, our tables indicated that your maximum build volume is 6.06” by 9.71” by 7.55”. If that’s the case, then how did we manage to print this monster octopus that measures 9.08” by 8.95” by 6.22”? Doesn’t the value for the X dimension exceed the stated print area for 5 colors?
This 5 color Cute Octopus Says Hello was printed at 280% scale, and sliced into 5 colors using the technique described in Update 25.
In this Update, we are going to expand on our Build Area Update numbers and introduce how model geometry can be used to seemingly exceed the published build area.
Here is a schematic of the nozzle positions in a RoVa3D Printer. This is looking from the top down, and the bottom of the diagram is the front of the printer. Note the numbers assigned to each nozzle position.
In this print, we assigned nozzles in the following order from left to right:
- Nozzle 1: Green
- Nozzle 3: Yellow
- Nozzle 5: Purple
- Nozzle 2: Red
- Nozzle 4: Orange
While the entire print is larger than the stated build area of the 5 nozzles acting together, because we weren’t printing with all colors throughout the entire object, we were able to leverage the nozzle positions to get a bigger print based on the model geometry. No single nozzle is printing outside of the single nozzle envelope. But the print as a whole is bigger than the stated 5 color print envelope.
In our experience, most models can be leveraged in this way to take advantage of more of the print bed by positioning the model so that the individual colors or materials are kept within the printable area of a given nozzle or nozzles. And then the print as a whole can be scaled up to use areas of the print bed that can’t be reached by all 5 nozzles.
Some additional tricks for printing this big:
- You cannot print with a skirt, so configure your slicing settings so that infill is printed first, and you prime your nozzles on the infill of the first layer. In a print this big, there was very little lost due to priming. Or, manually prime the nozzles before each color started its first layer. This is more finicky, but can be done if you need a perfect finish on the bottom of the print
- Object positioning is key. Not just in the X, but also in the Y. Our initial print of this monster had the object too far forward on the print bed, and nozzle 4 (orange) couldn’t reach the very front of the bed to print the little bit at the tip of the red tentacle. This was discovered during the printing of the first layer, and meant we had to reslice the model, which took over an hour on the Windows machine we were using
- Make sure you have enough filament on your spools if you are printing unattended. If you are attending the print, you can swap out a spool for a new spool at any time by pausing the print, and then using the commands in Pronterface to move the print head to a safe area to reprime the nozzle. Then just click Resume and Pronterface returns your print head to its original position and continues with the print.
- With a print this long, it would be a shame if something external interfered and ruined the print just as it was approaching completion. Make sure that your spools are unwinding cleanly, that there is nothing to potentially bind them, and that the area under the Y carriage is clear of any obstructions, as it will be descending almost all the way to the bottom.
After Update 28, lots of people have sent us questions like: If I print with 2 nozzles for material and two for support, how big can I print? We hope that this Update illustrates how difficult it is to answer that question in a generic way. The model geometry has a significant influence on how big you can print. If you send us your model, we can give you a firm answer on its printability, but hopefully with the information we’ve presented here you’ll have a good idea how to figure that out on your own.
A bit more about the Monster Octopus. She was printed in ABS at 400 microns and 15% infill. She used 895 grams of filament (we weighed her). Slic3r says that the following lengths of filament were used (from the end of the GCODE file):
- ; filament used = 60023.6mm (144.4cm3) (Green)
- ; filament used = 87487.8mm (210.4cm3) (Red)
- ; filament used = 93774.7mm (225.6cm3) (Yellow)
- ; filament used = 57537.2mm (138.4cm3) (Orange)
- ; filament used = 96007.0mm (230.9cm3) (Purple)
- Infill: 120mm/s
- Perimeters: 100mm/s
- External perimeter: 30mm/s
The print took about 22 hours to complete. Here are several pictures we took during the print process.