Datums in aligments

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

  • Datums in aligments

    I like to program with read points, then i do a rough dcc alignment and finally a final dcc alignment. My question is:
    1) Should i be bothered by the fact that in my final dcc alignment i don't always align to all datums?
    If the part has a very basic and easy to align datum structure i will. Example is Datum A is a plane (level & origin to this), Datum B is front edge (rotate and origin to y) and C is origin to x. (3,2,1 align). However, sometimes it's not this easy.
    2) Is it good practice to just pick up the datums as I go around measuring the part and then when it comes time outputing dims just output to datums or...
    3) Do i always have to create an alignment that matches the datums in the fcf.

    I hope this makes sense...

  • #2
    I always try to align my datums. In doing this. I am sure i am locking all 6DOFs and shouldn't have problems building my FCFs. I am sure, others do it differently. I work in the automotive industry and work with moulded and machined parts. I too like RP. I just started using them.
    Darroll
    2018R2

    Comment


    • #3
      Okay, thanks for the input. What sparked this question of mine is sometimes I have programs with dimension results that are way off...I'm talking like 80 inches. Obviously that's an error in my program so maybe not aligning to the datums is the problem. Another problem is i program offline sometimes and these results show up as nominal on the report but when it actually runs on the cmm like i said before, way off.

      Comment


      • #4
        I program off line too. Do you use CAD=Part? If not. Try snapping you cad and see what happens. Dont be alarmed by the screen saying you can't undo this because you can.
        Darroll
        2018R2

        Comment


        • #5
          No I haven't tried that. I'll give it a whirl. Is that kind of a check all to see if there are any red flags?

          Comment


          • #6
            Not really. What it does is match the CAD and machine coordinates so that they're in sync. Some programmers was taught to never use it as that's what I was taught but after research, I found that to be very useful and works.
            Darroll
            2018R2

            Comment


            • #7
              Oh i see. I'll mess around with it a bit.

              Comment


              • #8
                I use read points on 90% of my programs and all of my stuff comes out relatively accurate. Your measurement error must lie with how your subsequent alignments are set up.

                All a read point really is for is to roughly find the part. Once located, you build further alignments that build off of that to find your datums..align to them..recall the alignments you want and THEN go to town measuring stuff.

                If you can, post what you're working on and we'll be happy to try and offer you some advise.
                SF7107(PCD), SF454(PCD), 152614(Quindos), 9159(Quindos), 7107(Quindos), B&S Manual, M&M Gear Checker

                Comment


                • #9
                  Originally posted by bswagger View Post
                  I like to program with read points, then i do a rough dcc alignment and finally a final dcc alignment. My question is:
                  1) Should i be bothered by the fact that in my final dcc alignment i don't always align to all datums?
                  If the part has a very basic and easy to align datum structure i will. Example is Datum A is a plane (level & origin to this), Datum B is front edge (rotate and origin to y) and C is origin to x. (3,2,1 align). However, sometimes it's not this easy.
                  2) Is it good practice to just pick up the datums as I go around measuring the part and then when it comes time outputing dims just output to datums or...
                  3) Do i always have to create an alignment that matches the datums in the fcf.

                  I hope this makes sense...
                  perfectly normal. perfectly acceptable
                  Che Guevara is a communist scumbag.

                  Comment


                  • #10
                    Originally posted by bswagger View Post
                    No I haven't tried that. I'll give it a whirl. Is that kind of a check all to see if there are any red flags?
                    No. Red flags are usually (and irritatingly) shown in your forum Notifications::::::::::

                    Comment


                    • #11
                      Just to add... I think the goal is to measure your part with the least amount of cosine/probe error. You want to align your part in DCC to the features that will allow the least amount of error and will probe the part as normal to the surface as possible. It so happens that in most cases the Primary/Secondary/Tertiary datums are those features, but not always. I prefer to lock down my DCC alignment as tight as possible and then measure everything. I prefer to put my Datum Alignments and Characteristics at the end of the features so that they don't affect the nominals/actuals of the features if I need to change them for some reason during evaluation of the features.
                      PC-DMIS 2015.1, SP10, CAD++
                      Global 7/10/7, 5/5/5
                      Renishaw PH10MQ, PH10M, TP200

                      Comment


                      • #12
                        Max Tasty, I also like to put my Datum alignments at the end of the program. It seems to work out for me most of the time.

                        Dan_m I'll see if I can post an example.

                        Again, this question was sparked because I had a couple programs look great offline (of course all results were nominal) but when i ran the program on the machine I had a couple positions way off.

                        Comment

                        Related Topics

                        Collapse

                        Working...
                        X