Blank parts in sketches

bart

When I want to make a blank part in a sketch (let's say I want to draw a washer—a solid circle with a smaller blank concentric circle) it sometimes just makes the part I want blank solid. It appears to decide at random whether or not I deserve a blank area in my sketch. I usually just leave it to chance and work around it but there must be a way. Anyone know?

Many thanks,
Bart

andrew_troup

@bart
Check out the training videos on sketching, they explain this issue well

bart

Thanks! I must have forgotten.

viru

@bart , you can select or deselect solid circle or blank concentric circle (required portion) of sketch for extrude from model space window as shown below video.

bart

Hi Viru,

Thanks! I think I already knew this but I haven't used Onshape for a while so perhaps I was just frustrated.

Thanks for your help  

Bart

3dcad

At some point it was filed as a bug when you select whole sketch to extrusion and sketch holds 'washer type' -geometry which you would expect to extrude as a washer rather than only outer circle.

bart

3dcad said:

At some point it was filed as a bug when you select whole sketch to extrusion and sketch holds 'washer type' -geometry which you would expect to extrude as a washer rather than only outer circle.

A washer *is* only the outer circle... Do you mean the whole thing would extrude?

andrew_troup

I think bart and 3dcad are both taking (different) liberties with the word "circle"
In the exacting language of geometry, as used in solid modelling, a circle is a single, infinitely thin line.

Extruding a circle would produce a surface, not a solid body.

I think 3dcad meant the area bounded by the outer circle only, in other words, something which would extrude as a disk rather than an annulus.

3dcad

@andrew_troup Thanks (again) for understanding my point and explaining it with better terminology.