Is it possible to merge 2 objects & keep a hole from one of them?  

RE: Is it possible to merge 2 objects & keep a hole from one of them?

Rather than cutting the hole in the slicer, can you leave a gap in your panel where you want this to go, and add this as a part in that spot? Or is the panel someone else's model also?

RE: Is it possible to merge 2 objects & keep a hole from one of them?

In most slicers, you can’t truly “merge with boolean logic” the way a CAD tool does. Negative volumes work, but once you start stacking negatives + solids, alignment and ordering get messy fast (as you’ve noticed). Slicers are optimized for slicing, not robust CSG operations.

A few practical options:

• Use the keystone model itself as a negative: duplicate the keystone jack, set one copy as a negative volume, subtract it from the panel to create the hole, then place the normal keystone model back in the same position. This works best if you group/lock them so they don’t drift.
• Export a combined STL from a lightweight CAD tool: even something simpler than Fusion 360 (like Tinkercad or OpenSCAD) will let you do a clean boolean subtract + union in minutes.
• Fusion 360 really is the clean solution here — once you’ve done one or two boolean cuts, this exact workflow becomes faster than fighting slicer hacks.

Short version: slicers can fake it, but if you want a clean hole that perfectly matches the keystone and stays aligned, a quick CAD boolean is the least painful path, even if it feels like overkill at first.

RE: Is it possible to merge 2 objects & keep a hole from one of them?

Posted by: @fallon

I'm trying to put a keystone jack https://www.printables.com/model/60732-simple-keystone-slot into a solid panel & trying to do it in slicer. Is there a good way to add the keystone jack to the panel & get the hole in the jack to get removed from the panel?

I can create a negative volume box & add it to the panel to create a hole, but stacking a negative volume & then another object on top is being problematic. Even if I could get it to subtract a hole from the panel then add the jack on top, getting things lined up is pretty janky.

The obvious answer is learn Fusion 360 & stop doing slicer hacks, but I've had enough success with just the slicer I keep avoiding that.

It can be done, but isn't really straight forward. I was going to mention that the order of parts in the object tree is important, but I experimented first. From the shape gallery I tried to place a torus in the middle of one of the sign bases and cut a hole with a cylindrical negative volume. I then found that I was unable to drag the negative volume up in the object tree.

My next experiment worked. For this experiment I first placed a negative volume cylinder on the sign base where I wanted it and then saved that out as an stl. Loading the saved stl I found that the hole was cut out and I was able to place the torus at the same X-Y coordinates of where the negative volume was. Unfortunately, this technique is quite cumbersome for iteration. I feel like we are getting the the Jurassic Park quote: "Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should." If you don't want to learn Fusion360 (and be subject to AutoDesk's fickle free license limitations), you could learn FreeCAD. I should warn you though, until you develop a good workflow, modifying STLs in FreeCAD can be annoying. (I'm still at the stage of trying to remember the workflow to convert a mesh into a solid object for editing every time I need to modify a downloaded STL file. I just don't do it often enough, so I usually default to trying complicated slicer tricks like above. I haven't pulled a Zach Freedman and designed a full multi-color MakerChip in PrusaSlicer yet...)

For aligning parts of an object in PrusaSlicer, you need to have a grasp of where the origin of each part and the origin of the object is. In the "Part manipulation" pane there is a drop-down selector that usually defaults to "World coordinates". For this type of alignment, you'll want to change that to "Object coordinates". The origin (0,0,0) of the Object coordinates appears to be the 3D center of the bounding box of where the first part of the object was when the object tree was created. The reference point (part origin) that the X, Y, and Z relative coordinates for all other parts is the 3D center of each part's bounding box. You'll have to do your coordinate math by hand (or at least external to Prusa Slicer) because the coordinate text boxes don't accept formulas, even simple "100-10" to move something 10 mm in the negative direction of an axis.

RE: Is it possible to merge 2 objects & keep a hole from one of them?

Theres a setting in your preferences that allows you to reorder the tree.  Make sure order object by types is UN-ticked.  It is on by default.

RE: Is it possible to merge 2 objects & keep a hole from one of them?

Thanks for the info. Will fiddle with things. "Learn CAD again" has been on my to do list for a while, but I keep finding easy slicer hacks to avoid spending the time. I used Autocad 11 way back in the Windows 3.11 & 95 days back in school. But for whatever reason I'm not able to get in the right head space when I've started in trying to work on Fusion 360. I'm not opposed to their licensing, although I'm not a fan, It's probably just me not taking the time to watch some tutorials & beat my head against a wall & power through learning a new system. I've done a few things in TinkerCad over the past could years, but haven't had much success in doing anything more complex than a few primatives.