A quick guide to using a sketch grid in Onshape for 3D printing

When I started using this grid approach for my mounting hardware, I was initially worried about how the spacing would affect the final fit inside the enclosure. I was designing a bracket for a piece of heavy equipment, and I needed those threaded inserts perfectly centered. I experimented with a 4 millimeter offset between the points first, and then shifted it to 6 millimeters once I saw how the weight distribution would look. It made the design phase much cleaner than trying to manually align those complex hole patterns.

For me, the real benefit came when I was trying to make the top face components match the bottom plate. I had multiple diffrent sketch planes for different features, and keeping a consistent reference point across all of them was a pain. By projecting that initial grid onto each plane, I could see the alignment instantly without having to draw long guide lines or use alignment constraints. It sped up the tedious process of ensuring the holes didn't drift from one side to the other. I also found that if I needed to make a small adjustment to the overall part size, like reducing the footprint slightly, it was easy to just nudge the grid and let the entire pattern move. It's a lifesaver when you are working with tight clearances and need to make sure every single feature stays perfectly in sync.

This thread actually pushed me to try it out, even though my situation is a bit different. I mostly do woodworking templates and stuff, so I don't have a fancy setup, but I tried sketching onto a grid pattern for laying out shelf pin holes and it did help me stop guessing. I'm still not sure if I'm doing it right though. When you set the spacing, does it matter if the grid ends up not centered on your sketch origin? Mine seems a bit lopsided every time and I don't know if that causes problems later on.

I have to push back on the second reply though. Nudging the grid and expecting the whole pattern to follow sounds like it leaves your sketch undimensioned, wich is exactly the trap the original poster was trying to escape. If your holes are snapped to grid points but never dimensioned to each other or an edge, Onshape has no idea they shold stay put when the part changes. I tried something similar last year and my hole pattern wandered on the next regenerate. Sketch on the grid if you want, but lock it down with real constraints before you call it done.

One thing I'd add for anyone using this on curved or angled planes: check your grid spacing actually survives the projection. I laid out a vent pattern on a sloped face once and the on-screen spacing looked right, but the true distance between points along the slope was longer than what I typed in, so the holes came out stretched. Now I sketch a single dimensioned line between two grid points on the actual plane and measure it before committing to the full array, which takes about ten seconds and has saved me from two scrapped prints so far. Does the feature let you set an angular spacing too, or is it strictly rectangular rows and columns?