Adding Geometries to already extruded sketch

michal_bartak

Hello
This is my the first post so greetings to everybody and kudos to devs for this great software.

Some time ago I've learnt that using a single Sketch to create multiple shapes/parts from the single sketch is a powerful tool of onShape.
However, adding overlapping/inner figures to this sketch breaks already extruded parts. 

Let's imagine a circle extruded into a cylinder.


After adding another, inner circle to the existing one, the already extruded object changes


My question is: what is the strategy for using shared sketches for multiple objects, but do not break already extruded parts?
The only thing which comes to my mind is to create separate sketches which inherit some objects from the main sketch. but maybe there is something else?

Additional question: is there any way to command onShape to extrude using only specific faces/sketch regions or ignore others? Like in the image above, to extrude only from the outer circle ignoring everything inside?

With regards

robert_scott_jr_

Hello Michal. The method I used in the document below may not be the 'correct' way or a method that you might be able to apply in your project. I used two sketches and two extrudes. Sketch 'puck' is used to drive the puck as a solid (no center bore). Extrude 'puck' uses 'puck' sketch and controls the height of the part.The 'center bore' sketch drives the center bore 'remove' extrude.

By using a configuration table, different ODs, IDs and part height can be entered in the table and then that line of values in the table can be selected to drive your part by using the Configurations list that is now exists above the features in the panel on the left of the document.

If any of the configured parts are to be used in an assembly, any of the configured parts can be selected via a drop down list available during 'insert'.

- Scotty

 https://cad.onshape.com/documents/a5b530fa0708eb11b20a5b5b/w/a180778253e61d4b5153bb8f/e/08368c179598b9c10f39b6b4

glen_dewsbury

Yes to your question, You can select and unselect individual faces within the sketch to achieve the desired result. Select the regions with mouse pointer in the graphics area.
https://cad.onshape.com/documents/eeff86f87f2b3be9ae6915b8/w/c75821c5084576f01fba38b9/e/f545e845aebc8635dc2263e9

michal_bartak

robert_scott_jr_ said:

Hello Michal. The method I used in the document below may not be the 'correct' way or a method that you might be able to apply in your project. I used two sketches and two extrudes. Sketch 'puck' is used to drive the puck as a solid (no center bore). Extrude 'puck' uses 'puck' sketch and controls the height of the part.The 'center bore' sketch drives the center bore 'remove' extrude.

Yeah... I found a similar way. If I want to sketch multiple objects related to each other, (ie distance between outer and inner circle) I draw it on the master sketch and then derive selected figures onto dedicated sketches. This way adding intersecting figures on the master sketch doesn't affect already extruded objects while still relating to what is drawn on master sketch. Just hoped there is an easier way, not involving such amount of sketches.

michal_bartak

glen_dewsbury said:

Yes to your question, You can select and unselect individual faces within the sketch to achieve the desired result. Select the regions with mouse pointer in the graphics area.
https://cad.onshape.com/documents/eeff86f87f2b3be9ae6915b8/w/c75821c5084576f01fba38b9/e/f545e845aebc8635dc2263e9

Definitively, I wasn't precise enough. I meant to fix extrude feature to selected shapes, in a way that ensures that the extruded object will not change if other overlapping shape will be added to the sketch in future.