Embedded Marble Tea Light Holder by DaveMakesStuff

Last crawled date: 3 years, 3 months ago

WARNING: Embedding objects in your print is risky. Mistakes or oversights in slicing could result in collisions between your nozzle and the object!
That said, this sample tea light holder demonstrates some of the interesting effects that are possible when you feel ready to take the risk. See here for video: https://youtu.be/1aovdxwkPn0
This file is designed for 15mm diameter marbles and a hot end with a nozzle that protrudes at least 5mm from the bottom of the heat block. If these aren’t an option for you, don’t try this project!
The clear marbles shown are from Michaels: https://canada.michaels.com/en/clear-lustre-marbles-by-ashland/10556564.html. There is some variability in diameter, so use calipers to select six that are between 14.5 – 15 mm.
Slicing
The recommendations here are for Cura 4.8.0.
Import “Reference Marbles” and “Tealight Enclosure” into Cura. Right click and “Reset All Model Transformations” so that the reference marbles are sitting inside the tealight enclosures where the real marbles will go eventually. You will notice that the reference marbles are on long 0.1 mm diameter “stilts” so that they don’t automatically drop to the build plate when they are imported.
The reference marbles will be used to program “no go” zones for the nozzle, they will not be printed.
Select the “Reference Marbles” and open “Per Model Settings” to apply customized settings to this object. Check “Wall Line Count, “Top Layers, “Bottom Layers” and “Infill Density” and set all of these values to “0”.
In the main section under “Travel,” ensure that “Combing” and “Avoid Printed Parts when Travelling” are checked. The reference marbles are now “ghosts” that won’t actually print, but will be avoided when generating gcode. Slice the file and closely preview a few layers to ensure that the nozzle does in fact avoid the spaces where the real marbles will eventually be placed.
Next we need to set the height for the print to pause and allow you to place the marbles midway through the print. This is done by going in to the “Extensions” menu at the top bar: Post Processing > Modify gcode > Add a script > Pause at Height. Setting the height to 31mm will get you close, but if you want to be absolutely sure, refer to the pictures above that shows a cross section of the marble enclosure and find the layer height that corresponds to line indicated by the arrow. At this height, the marble will not be extruding more than 4mm (so you’ll clear the underside of the carriage) and the nozzle is far enough away that the sloped side of the nozzle with not hit the marble sideways.
I set “Retraction” at 8mm and “Extrude Amount” at 20mm, but you might have reasons for doing things differently.
The “Park Print Head x” and Park Print Head y” are set in conjunction with the coordinates in “Layer Start x” and “Layer Start y” in the “Travel” section of the main settings. Basically, make sure that when your print head returns from pause that is doesn’t slam into a marble on the way! I set x=190 and y=110 to have the nozzle come in from the right side and start on the right-most part of the layer. Slice these settings and preview them closely!
I set speed to 30mm/s, partly just because the Voronoi structures print better at lower speeds.
Printing
Printing the “Collision Checker” beforehand is not necessary, but it might give you some piece of mind at the critical moment of this print!
Once you are confident that you’ve got the settings right, start printing the tealight as you normally would. When the print pauses, you will want to remove any strings or burrs from the hollows where the marbles will sit. I use a spherical abrasive bit on a Dremel. Any imperfections will raise them marbles and put them at risk of collision. (There is a 1mm safety buffer, but things are still pretty close!)
Place the marbles and eyeball or place the “Collision Checker” over the marble to ensure that nothing is protruding higher than 5mm.
Clear the nozzle of any ooze.
Cross your fingers and “Resume Print.” Watch the next few layers closely and ensure that there are no collisions and that the marble stay properly positioned. Once a few layers have been laid down, you can stop holding your breath. The rest of the print will go as normal.
If you make a successful print, please share pictures! If you wreck your printer in the process, please also share pictures!