Negative/Subtractive 3D Bodies? - Page 1
Forum section: electronics / general

author: Pack34
author_rank: Frequent Contributor
timestamp: December 15, 2017, 03:36:51 pm
content: Is there a way to make a cylinder or similar Subtractive instead of Additive? Meaning to use a cylinder to punch a drill hole on a model.I'm trying to make all my components as true as possible using the built-in 3D modeling abilities in AD17/AD18.

author: julianhigginson
author_rank: Frequent Contributor
timestamp: December 17, 2017, 07:05:32 pm
content: I haven't checked ad18, but component bodies using extrusions are very simple in ad, and additive only... for anything complex, use proper 3d modelling software (even freecad) and export a stepfile you can then pick up in altium footprint editor.

author: pigrew
author_rank: Frequent Contributor
timestamp: December 17, 2017, 07:11:40 pm
content: Nothing new in Altium 18, it still can only sum extruded shapes and spheres.Personally, I find OpenSCAD as a very light-weight and quick way to make parametric 3D shapes. It's much quicker for me than FreeCAD. I use FreeCAD when I need to modify existing models.

author: julianhigginson
author_rank: Frequent Contributor
timestamp: December 17, 2017, 07:29:35 pm
content: Oooh. Openscad? Thanks for the tip, haven't tried that before. Yeah freecad is a little clunky, but once you learn it, it's pretty useful.

author: pigrew
author_rank: Frequent Contributor
timestamp: December 17, 2017, 07:36:03 pm
content: Quote from: julianhigginson on December 17, 2017, 07:29:35 pmOpenSCAD is a scripting language for parametric 3D modeling. The downside is that it's text-based so that may scare away many folks, but it's the software that I've felt the most comfortable with. The graphical editors like FreeCad just seem clunky in comparison when I want to input specific dimensions. One can't generate mechanical drawings or tolerance information from it, but it's great for day-to-day modeling for PCB software or 3D printers.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 19, 2017, 01:31:55 am
content: Nope.The workaround I use is arc segments.1. With line and arc segments, draw the profile of the shape you want to make.2. For circles, rubber-stamp them in the same location, and set the angles of the circles to 0-90 and 180-270 degrees. This gives you snap points in the cardinal directions (make sure snap-to-object is on).3. Place a 3DComponentBody. Adjust the vertices to the snap points. Grab the control point of a line segment, and press SHIFT+SPACE to cycle through the line modes. Select the arc mode.4. Drag vertices and arcs until you have the outline, and make a concavity that encloses the hole. Close the concavity by dragging its wall vertices on top of each other, leaving a 'bubble' in the middle. You can use two arc segments to make a complete circle; you use the 0 and 180 (say) snap points to position the vertices, and the 90 and 270 snap points to position the arcs.5. If this shape does not lay flat, say it's a vertical wall with holes in it: open the Properties dialog and press Convert to STEP. Adjust the angle and position as needed.Example:https://www.seventransistorlabs.com/Images/Output%20Interposer%201.jpgThe cylindrical structure on the right is hollow; the plates on the left have rounded bends, and open holes (note the shoulder washers are open in the middle).It's a pain, but this is the best you can do, short of a 3D tool.No way to make compound bends (spheroidal, toroidal or saddle shapes, say).Tim