Resolution and thin parts

- [Female Instructor] One of the main reasons for using a resin printer is the fine detail possible in a resin print. However, there are limits to the best possible resolution. In this movie, we'll characterize those limits and help you think about what resolution really means, both in terms of surface quality and your ability to create fine features. - [Male Instructor] The smallest feature or thinnest wall you can produce depends a little on which illumination technology your printer uses. LCD-based systems can use very high pixel densities to achieve a minimum theoretical feature size of less than 50 microns. However, the horizontal resolution is determined by these pixels. So, these machines will exhibit a layering effect in the X and Y axes, as well as Z. The projectors used by DLP printers also use pixels. DLP machines can be designed to either focus a projector on a small area to create finer details, or a larger area to enable larger prints. - [Female Instructor] Laser-based systems trace out a design within a layer one spot at a time. Equivalent to the way a filament-based printer's nozzle lays down one layer's worth of design. A computer graphics person might think of this as tracing out curves within a layer using a vector path. The horizontal feature size for these systems is limited by the laser's spot size, which is typically larger than the pixel used by other methods but still under a hundred microns. Because they direct the laser by physically rotating mirrors, panels will be smooth somewhat, which helps to obscure the effects of horizontal resolution. This also means the accuracy in X and Y is not dependent on the laser's spot size. The thickest layers you're likely to see printed on a resin printer are a hundred microns. The same is the thinnest you typically see from filament printers. Whilst resin printers can print layers down to about 25 microns thick. This achieves a much smoother surface than filament printing. This is good for painting and similar post processing, and for applications that require smoothness, like some medical uses. The flip side of this is that resin printers tend to have pretty small build areas compared to comparably priced filament machines. Resin printers also typically take longer than filament printers to print the same object. Though a variation on this method used by a few of the more expensive resin machines can be much faster. - [Male Instructor] Stair step effects caused by layering in the Z axis, as well as projected pixels in the X/Y plane, will affect surface quality. This is particularly noticeable on surfaces that are nearly, but not perfectly, parallel to one of these axes. Because the lines will be spaced further apart. Features smaller than the width of the pixels or laser spot used, or thinner than one layer in the Z direction, obviously can't be printed. These define the minimum theoretical feature size the printer can produce. However, those features also need to survive the printing process, as well as post-processing steps. The printer's peel procedure makes a difference here. Since the forces involved can easily break structures that are too delicate. Some printer manufacturers offer design guidelines for various dimensions of features on a print. In practice, a lot depends on how they're oriented, their other dimensions, and what they're attached to. If you want to push these limits, it will require a little trial and error. - [Female Instructor] Resolution is not a straightforward concept for many 3D printing technologies. The minimum feature size in the X/Y plane is mostly unaffected by layer thickness, which is the number typically used when describing resolution. Unlike filament printers, the laser spot size may be comparable to the layer height. Minimum feature size may really be the smallest feature size that will survive the peeling process, rather than the minimum size feature that can be initially laid down.