"Dimension to the Construction Line" in Revolve/Wheel exercise

laura_jones

I can't seem to add the dimensions as shown in the example, every time I try it only adds dimensions for the line on one side of the construction line. The example says "Dimension to the construction line to add diameter dimensions." Whenever I search for info about 'diameter dimensions' every forum just leads me to dimensions for circles. How do you actually do like in the image? More explanation in this part of the example is necessary.

laura_jones

Here is the image I was referring to

john_mcclary

There are a few rules you need to follow to place a diameter dimension.

First the center line must be a construction line (dashed)
Second the other line must be a normal line (not dashed)
Third you need to move your cursor below (or to the opposite side of) the construction line after selecting both your center line and object line.

After you place your dimension you can then change all lines to construction or object lines at will.

john_mcclary

To be honest onshape should show them diameter dimensions below the center line, as some people will try to mimic the placement of the dimensions while learning. (at least I do)

Jake_Rosenfeld

Hi @laura_jones

Please see "centerline dimensions" section of this help page for what we're talking about:
https://cad.onshape.com/help/Content/sketch-tools-dimension.htm

Thanks also @john_mcclary for explaining how to do this.  I've started the gears turning internally to get this terminology inconsistency ironed out.  Thanks for pointing this out!

bruce_williams

@Jake_Rosenfeld

Just to add another point on this subject -  I think the diameter symbols should be dropped or changed (to symmetrical?) we are not always making diameters with the geometry.  For example a mirror image can be used for extrudes.  

jackson_king

bruce_williams said:

@Jake_Rosenfeld

Just to add another point on this subject -  I think the diameter symbols should be dropped or changed (to symmetrical?) we are not always making diameters with the geometry.  For example a mirror image can be used for extrudes.  

Yes, I agree! Most times I use it as a symmetric dim not diameter. 

john_mcclary

jackson_king said:

bruce_williams said:

@Jake_Rosenfeld

Just to add another point on this subject -  I think the diameter symbols should be dropped or changed (to symmetrical?) we are not always making diameters with the geometry.  For example a mirror image can be used for extrudes.  

Yes, I agree! Most times I use it as a symmetric dim not diameter. 

This is true, Honestly I wouldn't care if they dropped the Dia symbol and just left it a dim like all the rest

Jake_Rosenfeld

Hi all!

Please put in an improvement request to remove the diameter symbol from this dimension type so that we can gauge interest on its removal, and start looking into the use cases where it is not used as a diameter.

bruce_williams

Here is the improvement request to remove diameter symbol.

Thanks!

john_mcclary

bruce_williams said:

Here is the improvement request to remove diameter symbol.

Thanks!

Thanks, cast my vote

jel111

I think you should be able to type the numeral of the dimension and then "dia" so there is no mistaking what is happening. Like "3 dia". On the 3 degrees angled line it won't let me add a dimension. All the others worked fine but the angled line gives me an angle degree or I get a dimension, nothing for diameter. Everything else including the constraints are the same it only allows a distance dimension.