Netherlands-based Printr released a new slicing feature for their Formide system that increases the reliability of dual extrusion 3D prints.
The feature, called the “Donut Wipe Tower”, involves automatically generating and printing an extra tower beside the 3D model in question. The idea is that during dual extrusion operations, it’s possible for drips to occur as hot end nozzles gradually heat up during color swaps.
If you’re 3D printing with a single nozzle machine, this is less of an issue because most machines have a startup sequence that simulates wiping stray drips by printing a standard pattern out of the way of the actual print.
However, dual hotend machines constantly heat up and cool down as they swap operating when multi-color layers are encountered. A heating nozzle will inevitably drip before it reaches full operating temperature. Typically this drip corrupts the 3D model by dropping onto (usually) the worst possible are of the print. Not fun!
Here’s how the “Donut Wipe Tower” works: near the actual 3D model, a hollow tower is also printed. The tower would, by definition, be at the same height as the partial print of the 3D model. The new slicing feature positions a heating nozzle in the hollow of the tower, where any drips will be caught in the tower when the hotend eventually moves away when it reaches operating temperature.
This leaves a cruddy looking tower beside the near-perfect print, but you’re tossing the tower away so that doesn’t matter.
The Katana slicer is also pretty smart about this feature. Here you can see it generates a tower only as high as is required to match the dual colors of the 3D model. It also optimizes the plastic used by the tower by making it thinner as it rises. Of course, the base is robust to ensure the constant wiping won’t tip it over during printing.
I’m thinking this feature could also be of some assistance to a single nozzle machine as well, particularly when printing complex geometries involving many retractions. I’ve noticed that high-end commercial extrusion machines have a fixed wiping system that is periodically engaged during print operations to ensure their hotend is always clean. The same process could be used on low-end machines, too.
To use the Donut Wipe Tower, you’ll have to use Printr’s Katana slicer, which is available with their Formide 3D printing set-top box.