5 Replies Latest reply on May 26, 2017 1:41 AM by Jaja Jojo

    I just have some questions about gd&t

    Eric Eubanks

      I'm starting the drawings for my pen and I just had a few questions.

      Do I need a tolerance for every dimension?

      How do I decide what tolerance to use?

      When do I need to use MMC LMC and RMC?

        • Re: I just have some questions about gd&t
          Christian Chu

          Just depend

          If it's a machined part, then you need to dimension/Tol everything so the guys on the floor know how to machine the part

          If it's a molded part, some dim can be avoid

          The tolerance is very much based on the fitting between parts in the assembly

          When you add GDT to your dwg, then you need to add MMC, LMC depends on how to use material for your parts

          • Re: I just have some questions about gd&t
            S. Casale

            I think you are in the wrong place to get a definitive answer relative to GD&T.


            May be worth taking some classes...

            • Re: I just have some questions about gd&t
              Rick McDonald


              There is not one answer for this.

              It depends on so many factors, for instance:

              Is this to be 3D printed from the model or machined, molded ...

              What standards does your company use?

              What is the purchasing companies requirement for tolerance?

              What are the specifications of any mating parts?

              There are just too many things that would determine this.

              My company doesn't use formal GD&T We just specify tolerances and make notes where things are critical.

              I have worked in places that did use "Basic" GD&T - some things defined in detail, others not.

              You should know at least basic GD&T but most companies don't require every designer/drafter to be an expert.

              • Re: I just have some questions about gd&t
                Jaja Jojo

                GD&T are use for parts that are mating together it's also used for reducing cost of manufacturing the tighter the tolerance the cost become higher. As mentioned above it depends on the kind of parts to be manufactured because in reality it is very hard to manufacture a perfect parts. Some company has a GD&T Specialist so that designer and engineer will concentrate in there worked.