Why can I not extrude from a plane contained inside a solid? (cannot extrude from an inside plane)

yehia_boctor

Examples on YouTube shows it is doable, but it is not allowing me to do it. It is allowing me to draw on the plane I created or was a primary plane (was contained inside my solid). But once I accepted the sketch I created (just a simple circle or a polygon) it turned to dashed lines and would not extrude. I have split the solid with my sketch plane, drew my sketch, extruded it with a remove or an add, then united the two parts of the solid again. I am sure there is an easier way of doing this. Is there something wrong (maybe) with the defaults that I am operating under, that I am not aware of that is not allowing me to do this.  I know it is doable (I've seen it on YouTube), so, why is it not allowing me??? 

NeilCooke

The solid is just obscuring the selection of the sketch - either select the sketch from the Feature list or use "Select other" to pick through the solid geometry. https://cad.onshape.com/help/Content/select-other.htm?Highlight=select other

Matt_Shields

"Select other" is powerful!  I also sometimes just hide the parts that are obscuring my sketches.

yehia_boctor

Thank you, Matt, for your response. I tried to reproduce what you demonstrated but, every time when I try to define what I am trying to extrude, it does not show it as available to click on.  It would allow me to highlight the borders of the shape only, and thus it would extrude a surface?!?! I could not get it to highlight the area to extrude a solid. How can I make a short video like the one you did to show you what I am going through. 

steve_shubin

@yehia_boctor said:

But once I accepted the sketch I created (just a simple circle or a polygon) it turned to dashed lines

If the lines are dashed, then the polygon is probably not showing a shaded fill within its' borders
If that is the case, then you will not be able to make a SOLID EXTRUDE

So you need to change the dashed lines to SOLID lines
Once you do that, then there will be a shaded fill within the borders of the polygon, and you will then be able to make a SOLID EXTRUDE

Another possible reason could be that you sketched a polygon that did NOT make a fully enclosed shape
If a sketch is fully enclosed, there will be a shaded fill to that shape, and then that shape can be used to make a SOLID EXTRUDE

Also, make sure extrude is set to SOLID