6 Replies Latest reply on May 11, 2012 12:28 PM by Lenny Bucholz

    Metric Countersink's

    Brad Joseph

      We have begun using more and more metric hardware in our designs. On a handful of parts we have some flat head machine screws M3-M5. The issue we are having seems to the be that the M4 for example sits far below the top of the part. Granted we would like it done a bit to ensure that its flush or below the surface slightly. But the screws seem to be further below that. It looks like we dropped M4's into a countersunk hole for an M6.

       

      Is the solidworks countersunk hole tables for metric countersunk holes correct? They seem much larger then they need to be. I'm using both the ANSI metric standard and the DIN standard to compare. Since McMaster is typically DIN standard parts. But they are essentially the same hole size. Can anyone clear this up? Or point me to a standard countersunk hole size chart for these screws?

       

      Thanks.

        • Re: Metric Countersink's
          Jody Stiles

          Hi Brad,

           

          I just tested the three hole types we offer in the Hole Wizard >> ANSI Metric >> Countersunk Holes and they all look corerct to me.  Did you override the values in the Hole Wizard Property Manager or the values in the Toolbox Configurator?

           

          C'sink hole comparison.png

            • Re: Metric Countersink's
              Dwight Livingston

              Jody

               

              Are you saying that the height of the head should match (meaning slightly shorter than) the height of the countersink? That doesn't work, since it doesn't take into account the different diameters.

               

              Dwight

                • Re: Metric Countersink's
                  Lenny Bucholz

                  if you look at the machinery's hand book, SW uses the theoretical sharp for the hole wizard hole and then SW makes the screw the same and then puts the flat edge on after.

                   

                  so when you put the screw in the hole it will be even with the top surface of the plate.

                  • Re: Metric Countersink's
                    Dwight Livingston

                    . . .  continued. Here's the rest of the McMaster-Carr drawing for 91801A244, which shows a 7.5 diameter. Doesn't say it's theortical sharp, but by the drawing it ought to be close. The diameter is 7.5. The sketch driving a SolidWorks M4 flathead shows a 9.4 dia at the top. The screw is going to be below flush by almost 1 millimeter. Sounds like a lot.

                     

                    As Lenny says, an ANSI flathead at maximum size of theortical sharp does equal 9.4mm.

                    Capture.PNG

                • Re: Metric Countersink's
                  Jody Stiles

                  Brad,

                   

                  Once I insalled the McMaster screw into the holes I see what you mean by it sinks way down.  My only guess is that the McMaster part is not to the ANSI Metric standard, if you put an ANSI standard screw in, it looks correct.

                   

                  Screws in holes.png

                    • Re: Metric Countersink's
                      Brad Joseph

                      McMaster Parts are not ANSI Metric standard there are DIN standard  or JIS. But in using the SW DIN standard...which seems to be the same as ANSI standard, it looks the same. And as i can assume alot of users typically buy from McMaster. We also get our screws from other vendors as well, and typically get in the same sized screw. I'm surprised this hasnt come up before. I mean granted it still works, and will still hold the part, but as far as aesthetics go when compared to other flathead screws that may be used near by, it kind of looks like we messed up in making the part.