Are external constraints possible?

w_s856

I am working on a highly complex object (just kidding, this is a threaded bolt) and came to wonder if it is possible to set some external, "outside of a sketch" kind of constraints to set the sizes of an obect.

In my example, there is a thread that I have the freedom to design (I am not bound by any norms or such) and both the core of the bolt and the thread can be any size. The only constraint I have is that the total diameter of the bolt must be at a certain value.

I have an opinion on the size of the thread so I would set it manually, but the core can be whatever (to reason, but I will handle this empirically). So constraining the size of the thread AND the final diameter would drive the diameter of the core (the blue double arrow above).

My question: is this possible?

Of course, I can do the computations by hand and in this case, it is easy. I can imagine that in some more complex situations it will be harder — so having such external constraints driving the ones in different sketches could be helpful. On the other hand it can quickly become a mess because you would not know what constrains what so i get it that it may be a very bad idea at scale.

robert_scott_jr_

If I understand your goal, variables and formulas (equations) will provide. In this document three variables were created: #thread_depth, #core_diameter, and #screw_diameter. The value of #core_diameter was set to #screw_diameter-#thread_depth. I think this is the 'outside of sketch' control you seek. - Scotty

eric_pesty

Simple, draw it as a side view in a sketch first, then reference that sketch for your next features (core, helix, thread profile, etc…)