Round parts... Extrude or Revolve. Which is better?

[kineoptics]

Round parts... Extrude or Revolve. Which is better?

I have been experimenting with different ways to start a round part. One is to start with a circle and extruded the cylinder, the raw stock, and then revolve cut the features in it. The other is to sketch the half cross section in detail and revolve boss. I've come to the conclusion that sketching the cross section is better because when you want to change it, the ends remain constrained better than if the cylinder is extruded longer and the revolve cut is taken. Has anyone else come to this conclusion?

One issue that I'm sure someone has a work around is that when sketching the half cross section, the dimensions are the radius and when brought to the drawing, it shows up as that and has to be changed to diameter. Not a big issue though, but is there a way to get it to show on the drawing as a diameter without manual intervention?

 

[indesign]

I am not real sure if this will help but......Draw a reference circle in the sketch with the center contrained to the centerline of your half sketch. Apply a dimension to it were the diamter is equal to the diameter you wish to revolve. Constrain the half sketch line to be tangent to the diameter (this way you only have a diameter measurement).

You will get a diameter dimension but it will spin like it is free from a actual side.

 

[volker]

Hi,
i think it depends on what you want to model.
A simple shaft i think is easyer to revolve.
Dimensionning the diameter, i prefer to mirror the sketch and then convert it to refference geometry. I am then able to add a dimension for the diameter.
For more complex designs, i would prefer to extrude the cylinders one by one. The distances you make with ref. planes.

As soon as there are changes, a complex sketch may cause errors.
The best way to avoid is to have more, but simple features.

Cheers
Volker

 

[cgriffin]

I've been making a number of round lathe-cut parts lately, and I sketch the profile & revolve it. While the dimensioning is a pain (1/2 the OD...), the overall process seems less painful.

 

[cdub]

revolve vs extrude

My preference is to do both:

Draw a circle and extrude to represent the raw stock.

Then used revolved cuts to bring in the features one or two at a time.
If you reference the features to reference planes you can move them without modifying the sketch. By doing multiple revolved cuts it keeps the sketch complexity managable.

I personally don't like the "wedding cake" method of stacking, because when you "roll back" the part to make a change, the part gets shorter, and you lose visiblity to both ends, but that's just a personal preference.

Anyway, my 2 cents.
Have fun,
cdub