Is there a better way?

j_keslar

Edit - link to public document - https://cad.onshape.com/documents/ab3dc1d2f03f2a6979d646f8/w/d2a6be02f4cc02ae3fabda83/e/fde1944c6636c686f66710ea

I'm very new to OS - I'm learning, and so far, have been able to figure out how to get things done by Google, video, these forums, etc. I created a part and I can't quite figure out the best way to center the removed extracts from the original part (if that makes any sense). I started with a solid rectangle derived part from another document. Then, created construction lines on the top surface of that derived part to get center lines and a center point on that face. I then created a new plane (line angle) based on one of the center lines. Then created a new sketch based on plane 1 that became the circular center point extrude. All good - it's centered top to bottom and front to back on that derived part. Then created 2 new planes (plane 2 and 3) based on the front and back faces of that circular extrude, then added a square and rectangle feature tied to those planes. With that done, it's exactly what I wanted, and I could probably live with it like that. I decided, however, that I now want to center the combination of those void extrudes - the square is ~4mm wider than the rectangle, so just a bit overall off center front to back. After messing with the planes a bit, and trying to create some equal construction lines to no avail, I finally found that I could offset the circular extrude. By trial and error, got it close to center by just messing with that offset and using the measure tool to keep checking distances from the edge of the derived part to the edges of the square and rectangle. It worked, but I know I'm going to create some similar parts, and it seems like there's a better way to do what I did…. Any advice would be appreciated.

glen_dewsbury

No need for any of the additional planes if you learn about implied mate connecters for aligning your sketches. I also used the measuring tool to set center of circle sketch. The cross hairs sketch is also gone.

https://cad.onshape.com/documents/bd3575e2cbb44677acf12916/w/f9c0db12618d04249e1c4afc/e/337741db49929ea4b9a424d7

glen_dewsbury

Can you post a link to public document. Easier to analyze the issue.

andrew_kleinert

One tip is to look for symmetry in your design, and use the Mirror feature to implement that symmetry.

For example, with this design it looks like there are options to mirror in the front plane or mirror in the right plane.

This looks to be a spool holder of some form? If so, my instincts would be to mirror in the front plane - this is because a spool holder faces a user, and the part would have symmetry to the left and right of the spool. If you did it this way you wouldn't have needed to create both plane 2 and plane 3 - you would have only needed one of them. Also, if you did it this way, the two slots that hold the axle would need to be below the mirror in the feature tree because they're different.

Alternatively, you could mirror in the right plane. This would require fewer features because everything is symmetrical. But that not necessarily be the best option.

For example: You may find that your design intent (functional requirement and/or usability and/or aesthetics and/or manufacturability, etc, etc) drives your design to be symmetrical around one plane, and that makes that plane intuitive to mirror between. Conversely, your design may happen to be symmetrical around another plane more by accident, and in that case it might not make sense to choose that accidental plane to mirror between.

The_M100

I think it may also be possible to do it with symmetric extrudes.

j_keslar

I edited my original post with the link to the public document. Thanks for the input so far…

MDesign

@j_keslar to center your sketches you'll have to learn about constraints. the symmetry constraint will help a lot.

glen_dewsbury

No need for any of the additional planes if you learn about implied mate connecters for aligning your sketches. I also used the measuring tool to set center of circle sketch. The cross hairs sketch is also gone.

https://cad.onshape.com/documents/bd3575e2cbb44677acf12916/w/f9c0db12618d04249e1c4afc/e/337741db49929ea4b9a424d7

rick_randall

Don't forget to use the "equal constraint" and construction lines to center geometry in sketches, (assuming you want to always maintain that centered relationship). This is especially handy if the dimensions aren't established yet .

glen_dewsbury

Correction.

I mentioned implied connecters. You'll get better search results if you use IMPLICIT mate connecters.

j_keslar

Thank you Glen - didn't expect this much detail, but what a great explanation and example. I knew I unnecessarily over-complicated the model - this helps me greatly in understanding the use of mate connectors and variables. I did the crosshairs sketch as I thought I may need to go back and modify the derived part, and hoped that by doing the crosshairs that I'd be able to maintain center if I changed the derived part geometry (which I did have to do, and it did maintain center with the new version of the derived part). The variable in your version of the model is more elegant approach.

Thanks again!

glen_dewsbury

One more detail. Once I clicked to your circle extrude method, no need for measurement variable as well. It can be placed at an implicit point on the back face. Just use a starting offset when extruding the circle. Keeping a simple modal clean is good practice for when a more complex model comes up and it will. Clean models come with practice.

https://cad.onshape.com/documents/bd3575e2cbb44677acf12916/w/f9c0db12618d04249e1c4afc/e/337741db49929ea4b9a424d7