Constructing a Circle from Cone

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Constructing a Circle from Cone

    I am measuring a very small internal cone. I have to construct a diameter at a surface of where the .1320 is dimensioned. The problem is that the part is so small that I can't see if it's actually hitting on the correct surface when measuring the cone.
    I am using the CAD model and according to that it looks okay. After the measurment in the graphics on the cone vector do not match the alignment of the part. Has anyone done anything this small and internal before ?

    Is there best practice in measuring a cone as small as this one ?

    My other question is when I create the diameter at the surface I need to create it to to plane. Do I use projection or intersection to the plane ?
    DEA MISTRAL
    PC DMIS CAD++
    Version 2013
    Windows 7 64bit
    DataPage+ 2011 MR1

  • #2
    That is very small. What size tip are you using? Is the actual angle of the cone correct after you measure? That is one way to know if you are getting good hits in the cone or not. The best way to construct the circle from the cone is to use the gage diameter/height radio buttons near the bottom of the column to the left of the selection window for a constructed circle.

    Measure the cone.
    Choose construct circle.
    Highlight the cone in the selection window.
    Use the radio button and put in the distance from the plane in the height box.
    Enter .132
    HTH
    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

    Comment


    • #3
      Originally posted by Wes Cisco View Post
      That is very small. What size tip are you using? Is the actual angle of the cone correct after you measure? That is one way to know if you are getting good hits in the cone or not. The best way to construct the circle from the cone is to use the gage diameter/height radio buttons near the bottom of the column to the left of the selection window for a constructed circle.

      Measure the cone.
      Choose construct circle.
      Highlight the cone in the selection window.
      Use the radio button and put in the distance from the plane in the height box.
      Enter .132
      HTH
      The angle has varied +/- 10 degrres on different ways I have inspected it. The angle on the print is reference because they want to hold the .1320 +/-.0005 and the intersection of the cone and the other suface a diameter of .035 +/-.001. So I am not even quite sure what the angle could be. I am working on getting a rubber mold of the part to verify but I am also having a difficult time with that.
      DEA MISTRAL
      PC DMIS CAD++
      Version 2013
      Windows 7 64bit
      DataPage+ 2011 MR1

      Comment


      • #4
        Mattfurtaw,

        You're on a better path, in trying to do a mold of the part, and then check it out on an optical comparator.

        Don't know if you have managed to somehow measure the cone yet.
        If you can, try to measure a minimum of 3 points at the top of the 0.132 dimension. Construct a plane from these points then meaure the cone, and last, intersect the cone and plane.

        As I said, don't know if you are able to pick up on these features with the cmm.

        Regards,
        ZydecoPete
        sigpic

        Comment


        • #5
          I don't think that a comparator is accurate enough for +/-.0005
          Try taking PCDMIS out of guess mode and tell it that you are measuring a cone, and manually measure it if at all possible. Note proper vector direction.
          Also try constructing a reverse cone of your original cone. Maybe PCDMIS is inverting your cone.
          I would construct an intersect circle of the cone and plane. If you construct a projected circle then as the angle changes on the cone and the location of the plane moves around (.132 +/-???), it will construct the circle from the actual measured features. More accurate in my oppinion.
          If you use the radion button and put in .132 that makes the .132 an absolute with no tolerance compensated for, from any dimensional changes.
          Time for the Trolls to leave.

          Comment


          • #6
            measured cone

            HI
            What are you search? major diameter, location , of cone angle?
            If you need know diameter value and location , you can use one ball with diameter calibrated and measured with sphere, for obtain location and measure height and calculate diameter.
            If you need touch cone directly, you can verify if form error and angle cone is correct

            Comment


            • #7
              To test your measurements, measure the feature as an internal auto-cone. Create a generic plane at the specified distance ( .1320 ) and do an intersection circle (select the cone first and plane second). This should give you an idea of whether or not you are measuring it correctly.
              sigpic
              Xcel 15-20-10 - PFXcel 7-6-5 - Merlin 11-11-7 - Romer Absolute 7525SI
              PCDMIS 2012
              Windows Office XP

              Comment


              • #8
                I would use a shadow graph for this (projecter). We use a 50x lens for some pieces and we can easily repeat our measurements within 10┬Ám.
                Recently jumped from 3.5 Mr 2 CAD
                to 2012 CAD++

                Comment


                • #9
                  Originally posted by Peter Warcholyk View Post
                  Mattfurtaw,

                  You're on a better path, in trying to do a mold of the part, and then check it out on an optical comparator.
                  Rather than making a rubber model, have you ever used "Facsimile", a compound that is designed for checking finishes, dimensions etc. I have successfully used it to check surface finishes/measurements in internal seal grooves and other small,hard-to-measure locations that could only be economically checked by sectioning a piece.

                  I purchase it from Flexbar Machine Corp.
                  sigpic
                  Just a scooter pilot

                  Comment


                  • #10
                    Originally posted by 56flh View Post
                    Rather than making a rubber model, have you ever used "Facsimile", a compound that is designed for checking finishes, dimensions etc. I have successfully used it to check surface finishes/measurements in internal seal grooves and other small,hard-to-measure locations that could only be economically checked by sectioning a piece.

                    I purchase it from Flexbar Machine Corp.
                    We use Facsimile and RTV from Dupont. Facsimile is great for tighter tolerances as it it more stable.
                    When in doubt, post code. A second set of eyes might see something you missed.
                    sigpic

                    Comment


                    • #11
                      The tolerance on this feature is +/-.0005 and I do not believe that by using a optical comparator is suffiencient enough. You have too much human error in person to person measurment.

                      I have also used Facsimile before but again we are talking about +/-.0005 toleracne in addition to inspecting numberous parts for a long period of time. And I have also found that facsimile is not easy to use on small internal features.

                      I am using a probe size of .012 on my DEA and I do believe that it is possilbe to measure this but it's just getting the software to understand what I am trying to acheive.

                      Thank you for all of your input.
                      DEA MISTRAL
                      PC DMIS CAD++
                      Version 2013
                      Windows 7 64bit
                      DataPage+ 2011 MR1

                      Comment


                      • #12
                        Originally posted by mattfurtaw View Post
                        The tolerance on this feature is +/-.0005 and I do not believe that by using a optical comparator is suffiencient enough. You have too much human error in person to person measurment.

                        I have also used Facsimile before but again we are talking about +/-.0005 toleracne in addition to inspecting numberous parts for a long period of time. And I have also found that facsimile is not easy to use on small internal features.

                        I am using a probe size of .012 on my DEA and I do believe that it is possilbe to measure this but it's just getting the software to understand what I am trying to acheive.

                        Thank you for all of your input.
                        It entirely depends on what size lens is used...
                        Recently jumped from 3.5 Mr 2 CAD
                        to 2012 CAD++

                        Comment


                        • #13
                          Originally posted by mattfurtaw View Post
                          The tolerance on this feature is +/-.0005 and I do not believe that by using a optical comparator is suffiencient enough. You have too much human error in person to person measurment.

                          I have also used Facsimile before but again we are talking about +/-.0005 toleracne in addition to inspecting numberous parts for a long period of time. And I have also found that facsimile is not easy to use on small internal features.

                          I am using a probe size of .012 on my DEA and I do believe that it is possilbe to measure this but it's just getting the software to understand what I am trying to acheive.

                          Thank you for all of your input.
                          Skip the mold making and the CMM attempts.

                          If your tolerance is that tight then you should be using a vision system to "look" down into that bore and check the diameter directly. A good optical comparator with surface illumination sufficient to allow this type of measurement will also work. They are accurate enough if the measurement is directly on the part. The mold will transfer too much variability.
                          Links to my utilities for PCDMIS

                          Comment


                          • #14
                            cone

                            ok........create a offset point where the dim. is taken from.......from that point create a plane ( in cast )......then create a circle intersecting the cone and the plane......ask the dia. of the circle

                            Comment


                            • #15
                              ok........create a offset point where the dim. is taken from.......from that point create a plane ( in cast )......then create a circle intersecting the cone and the plane......ask the dia. of the circle

                              Comment

                              Related Topics

                              Collapse

                              Working...
                              X