Tall 3D printing can be quite useful, but height can cause many issues.
Most 3D printers offer a cubic build volume of reasonable size, usually between 200-400mm on a side. However, there are some machines that offer taller build volumes.
A typical manufacturer’s approach would be to take their standard 3D printer model and “stretch” it. This is done by simply lengthening the Z-axis hardware. Many 3D printer manufacturers have done this, introducing an “XL” type model.
Some hobbyists have done their own conversions using this approach. Here’s an example of how Reddit contributor GiaoPham0403 modified a stock Creality Ender-3 into a tall 800mm device. One problem encountered was a requirement to tweak the firmware to allow the motion system to travel farther than 250mm.
But that’s not the only problem with tall printing. After seeing this extreme modification, I thought it might be useful to explain three common problems encountered when printing tall items using different 3D printing processes.
Tall FFF 3D Printing
It might be mechanically possible to stretch a FFF 3D printer in this way, but there will be a big problem: model sway when using i3-style devices.
An i3 3D printer moves the Y-axis along the print plate. The plate literally moves forwards and backwards during printing. If the system is tuned properly, it should work fine.
But trouble begins when you get taller.
How sway increases in tall FFF 3D printing [Source: Fabbaloo]
In “short mode”, the print slightly oscillates, with a minuscule offset from the model to the nozzle.
Conversely, in “tall mode”, the model may experience significant swaying, and the gap between the intended position of the model and its actual location broadens. This circumstance could negatively impact print quality, and in drastic instances like the elongated Ender-3, it could even jostle the print off the plate completely.
The effect would hinge on the geometry, motion, utilization of supports, and other elements. While it may be feasible to offset this with progressive firmware, it’s advisable to circumvent tall i3 printing.
Tall Resin 3D Printing
Is it likely to encounter problems with tall prints in resin 3D printing? Undeniably so!
This effect has been something I’ve stumbled upon more times than I can count. Even though the plate remains stationary unlike in FFF 3D printing, the entire set up is inverted. The model is suspended from the plate throughout the course of printing.
Higher prints necessitate a larger amount of material, and as a result, become heftier as the print goes on. Hence, it is imperative for the support structures to be capable of bearing that weight.
Click Here to see an image on how support structures ought to adapt in tall resin 3D printing [Source: Fabbaloo]
On more than a few occasions, I’ve enlarged a model and failed to bolster the support structures. This oversight often leads to the model detaching from the supports mid-print, plummeting into the vat. The processing of the subsequent layer then grinds down the debris onto your sensitive FEP sheet at the vat’s base, rendering your day less than ideal.
Tall LPBF 3D Printing
Height impacts also take place in LPBF 3D printing, where a laser is deflected of a galvanometric mirror positioned at the printer’s apex. The mirror has the capability to direct the laser dot to any location on the printing bed. The concept revolves around selectively fusing specific areas of the powder, executing this on a layer by layer basis. This procedure finds its use in SLS, SLM, DMLS, and similar powder-based 3D printing methods.
However, an issue arises. When a greater build volume is necessitated, the mirror has to reflect the laser at a more acute angle. This action results in the distortion of the laser dot, which is not desirable. The energy within the dot is diffused over a wider area, thus making the powder melting process more challenging. This gives rise to a multitude of quality problems as the energy becomes inconsistent based on the print area’s zone.
The solution used by many LPBF 3D printer manufacturers is to make the machine taller! This positions the mirror in a place where the angle is decreased and the laser dot maintains a reasonable shape.
In the referenced image you can see a standard setup on the left, where the laser dot is reasonable in all zones. However, in the center configuration a larger build area results in a distorted laser dot. This is rectified in the right image, where the mirror is position high to reduce the angle.source
The next time you see a tall 3D printer or print job, recognize there are almost certainly a number of unique challenges in making it work properly.
Via Reddit
“Why did the 3D printer go to therapy? Because it had too many layers of unresolved issues!”
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