Countersink hole from opposite face

tom_auger

The above is an extruded shape. I'm using the Hole feature and the points for the holes have been drawn on a plane derived from the "bottom" of the shape. Thus, the countersink is at that location. I'd like the countersink to start at the opposite face, to create a countersunk "pocket" hole in the curved face. The hole is not normal to the curved face.

A manual strategy would be to offset the drawing plane for the hole by eyeballing it to match where I think the hole would intersect the curved face, but if I ever changed the slope of the curve, or adjusted some other aspects of the drawing, the hole would no longer align.

I'm wondering if there is a parametric technique I'm missing? It would be cool if you could chose which "end" of the hole the countersink starts from...

edit: tag: "farside countersink" - obviously I'm not the first person to wonder about this!

owen_sparks

Howdy.

Good news; that's an easy fix.

A hole will be projected either up or down from your sketch point. As your point is in the middle you only have "half a hole". 

One thing that is not obvious at first is a counter-bored hole will be projected towards a part and respect the minimum CB required.  There is no need for the sketch point to touch the part, it can be above it if that makes positioning the sketch easier.

Example:-

Ensure the "Start from sketch plane" option is unchecked:-

Clickme

Hope that helps,

Owen S.

tom_auger

This is unfortunate. Sorry, it's not obvious from the viewing angle, but the hole is clipped at the intersection of the plane and the surface being "drilled".

Here's another view.

tom_auger

okay at this point I'm just going to assume the tool just doesn't work properly on curved surfaces and will focus on extruded shapes and a boolean subtract.

I'd love to get some seasoned veterans' opinions on this particular design challenge.

owen_sparks

Howdy.

Good news; that's an easy fix.

A hole will be projected either up or down from your sketch point. As your point is in the middle you only have "half a hole". 

One thing that is not obvious at first is a counter-bored hole will be projected towards a part and respect the minimum CB required.  There is no need for the sketch point to touch the part, it can be above it if that makes positioning the sketch easier.

Example:-

Ensure the "Start from sketch plane" option is unchecked:-

Clickme

Hope that helps,

Owen S.

tom_auger

Tried it as you suggested, Owen. Worked exactly as advertised. Where I had messed up was the position of my drawing plane - I was thinking in terms of where the center point of the hole would pierce the face, as opposed to the outer edge of the counterbore, which would require my plane to be considerably higher up.

Thank you for the excellent advice!

owen_sparks

Sure thing, it's like that here. 

Glad you've got it working

Owen S.