Creating a sphere

catherine_jones

I'm trying to create a sphere in Onshape.  I thought it would simply be drawing a circle and a line through it to create an axis to revolve around ,then doing a revolve but that isn't working. Is that the right thing to do and i'm doing it wrong or should i buy doing it a different way?

andrew_troup

You could use your original sketch , @catherine_jones , provided it's correctly drawn, by selecting the sketch REGION of a single semicircle (rather than clicking on the arc, click inside it: instead of just the entities highlighting, the area within them will change colour)

There is a rather obscure reason why you cannot use the whole circle, even if revolving less than 180 degrees, which you would have to do to avoid the problem of the resulting solid self-superimposing (also see note #):

The problem would be that the resulting sectors, like an orange with two opposing segments removed, would share a single edge at the junction of two solid shapes. This is a no-no for solid modellers, usually referred to as "zero thickness geometry"

Note #: In your original attempt, the feature name (probably "Revolve 1") would have changed to red to indicate a problem.
If you had hovered over that name, a pop-up hint would have appeared, explaining the nature of the problem (probably using the expression "self-intersecting")

andrew_troup

Draw a semicircle with a diameter, not a full circle. That should do the trick

andrew_troup

You could use your original sketch , @catherine_jones , provided it's correctly drawn, by selecting the sketch REGION of a single semicircle (rather than clicking on the arc, click inside it: instead of just the entities highlighting, the area within them will change colour)

There is a rather obscure reason why you cannot use the whole circle, even if revolving less than 180 degrees, which you would have to do to avoid the problem of the resulting solid self-superimposing (also see note #):

The problem would be that the resulting sectors, like an orange with two opposing segments removed, would share a single edge at the junction of two solid shapes. This is a no-no for solid modellers, usually referred to as "zero thickness geometry"

Note #: In your original attempt, the feature name (probably "Revolve 1") would have changed to red to indicate a problem.
If you had hovered over that name, a pop-up hint would have appeared, explaining the nature of the problem (probably using the expression "self-intersecting")

catherine_jones

Thanks Andrew.  
  Yes using a semi circle worked perfectly.  In hindsight it seems obvious now.  Yes I saw my resolve name went red. didn't realise it gave me a tip on the problem

daniel_chow

Old post I know, but I was searching up how to make a sphere in onShape, just use the revolve command around a curved line and a center line. 

Here is something relevant and useful for anyone else searching how to do this... how to make it hollow:
https://www.youtube.com/watch?v=05VamP3F-4I