model as master / dimensionless drawing

joshua_sams

so my question here is "what do other people call this?"
I'm trying to align with some industry standard terminology if possible

currently our release process requires a full drawing in order to approve and release a part.
many manufactures including one of our main ones don't use drawings for dimensions. they use the STEP file.
we typically know which manufacture we will be using before we finish designing the part.

that means we are wasting our time making a full drawing.
we are now producing drawings with no dimensions, we only include info not already included in a step file such as threads. material. surface finish. treatment processes. part number. labelling ect.

this also means the model controls the dimensions rather than the drawing. this in my previous company was called model as master. 


so. dose anyone else do something similar? if so. what do you call it?

thanks
josh

S1mon

Critical to function drawing.

Typically there’s also a note that references the .STEP file to say that it is basic, and all geometry must be within some surface tolerance of that using GD&T. 2D drawings can be considered a legal tool, so the GD&T is a way to say that everything must fit within a theoretical offset of the surfaces. This is often ok for parts that are machined or smaller injection molded parts.

ISO 2768 can also be a good way to specify tolerances without dimensioning everything. It’s based on feature sizes, and has a fine and course option. It’s better at dealing with giving a little more tolerance for larger features.

For injection molded parts, SPI has tolerance tables which increase tolerances as features get larger, and it has different tolerances for different types of features.

nick_papageorge073

In my experience, the term "master model" (sometimes also called "skeleton model"), which is close to what you wrote, but not exactly, is a CAD strategy that has nothing to do with 2D drawings. Just pointing that out incase someone gets confused by the terminology.

joshua_sams

S1mon said:

Critical to function drawing.

Typically there’s also a note that references the .STEP file to say that it is basic, and all geometry must be within some surface tolerance of that using GD&T. 2D drawings can be considered a legal tool, so the GD&T is a way to say that everything must fit within a theoretical offset of the surfaces. This is often ok for parts that are machined or smaller injection molded parts.

ISO 2768 can also be a good way to specify tolerances without dimensioning everything. It’s based on feature sizes, and has a fine and course option. It’s better at dealing with giving a little more tolerance for larger features.

For injection molded parts, SPI has tolerance tables which increase tolerances as features get larger, and it has different tolerances for different types of features.

we actually use ISO 2768 Fine at the moment for all our tolerances.

some of our manufactures have a stated minimum tolerance though and will work to that and ignore anything on the drawing as per there user agreement. its often a reasonable tolerance like 0.1mm which really covers a lot off the stuff we do. bracketry and jigs etc.