Calibrate the unit - PH10M

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  • Calibrate the unit - PH10M

    Is it possible to use the "Calibrate the unite" feature to generate an error map for a PH10 head? The documentation is a bit unclear. In the Core documentation it indicates this is for infinite wrist devices only. In the CMM docs it indicates infinite or indexable wrists. Here is what I would like to try if it is possible:

    - Use "calibrate the unit" to generate an error map of PH10 by measuring the "T" configured tip at all possible rotation angles.
    - Load one of our multi-purpose tip builds and calibrate a dozen commonly used angles through the range of the device with the "use unit cal data" box checked.
    - Run a qualification check using three of the physically qualified angles and 3 of the angles that would be calculated from the error map data.
    - If everything checks out feel confident that I can use this tip build at any angle even though I have only physically calibrated a dozen of them.
    - repeat tip calibration once a week. Repeat wrist mapping once every 3 months.

    We currently calibrate EVERY angle on two our tip builds once every two weeks (we alternate weeks so each build gets calibrated every other week) We need to do this for two different machines so it adds up to a lot of calibration time. We have to do this because we have hundreds of programs dating back over 10 years that use these same tip builds and each program could potentially use a dozen angles or more. To be sure we are ready for whatever comes along we calibrate every angle. This takes a long time so there is strong incentive for people to forget. If we can reduce the time for calibration it will get done more often. Even if the error map isn't quite as accurate as calibrating each angle physically the increased frequency of physical calibration on our more commonly used angles will offset this risk.

    That's my thinking. Please poke as many holes in the logic as you can find.

    Thanks,
    Jeff
    2013MR1 SP6
    Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

  • #2
    No, as the HELP file states it is for infinite indexible heads. Continue with your regimen.
    sigpic

    James Mannes

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    • #3
      Ok, but the CMM documentation specifically says you can do this with indexable wrists and mentions the PH10 specifically:

      Calibrate the Unit (For Indexable Wrist Devices):
      This option is used to error map a Probe Head or a Wrist device. This section describes error mapping an indexing probe head such as the PH9, PH10, or the Zeiss RDS. A special probe configuration, consisting of three styli of the same diameter, is placed in the probe head and as many tip orientations (all possible orientations is best) that the user desires are measured with this probe configuration. Generally, you should arrange the styli in a ‘T’ configuration at least 20mm tall and 40mm wide (like a star probe with styli at 20mm from the center). The farther the styli are separated, the more accurate the error map will be.
      Once you have measured all possible orientations using the special configuration, you will be able to change probe configurations without having to do a calibration of the entire tip list. Each of the orientations measured in the original map will now automatically be calibrated in the new configuration. PC-DMIS provides complete support for calibrating and using all Renishaw and DEA probe heads, as well as the Zeiss RDS head.
      I'm using 2011 CAD, by the way. Is this a new feature and the core documentation hasn't been updated yet?
      2013MR1 SP6
      Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

      Comment


      • #4
        Originally posted by DaSalo View Post
        Is it possible to use the "Calibrate the unite" feature to generate an error map for a PH10 head? The documentation is a bit unclear. In the Core documentation it indicates this is for infinite wrist devices only. In the CMM docs it indicates infinite or indexable wrists. Here is what I would like to try if it is possible:

        - Use "calibrate the unit" to generate an error map of PH10 by measuring the "T" configured tip at all possible rotation angles.
        - Load one of our multi-purpose tip builds and calibrate a dozen commonly used angles through the range of the device with the "use unit cal data" box checked.
        - Run a qualification check using three of the physically qualified angles and 3 of the angles that would be calculated from the error map data.
        - If everything checks out feel confident that I can use this tip build at any angle even though I have only physically calibrated a dozen of them.
        - repeat tip calibration once a week. Repeat wrist mapping once every 3 months.

        We currently calibrate EVERY angle on two our tip builds once every two weeks (we alternate weeks so each build gets calibrated every other week) We need to do this for two different machines so it adds up to a lot of calibration time. We have to do this because we have hundreds of programs dating back over 10 years that use these same tip builds and each program could potentially use a dozen angles or more. To be sure we are ready for whatever comes along we calibrate every angle. This takes a long time so there is strong incentive for people to forget. If we can reduce the time for calibration it will get done more often. Even if the error map isn't quite as accurate as calibrating each angle physically the increased frequency of physical calibration on our more commonly used angles will offset this risk.

        That's my thinking. Please poke as many holes in the logic as you can find.

        Thanks,
        Jeff
        Poke, poke. Its a huge waste of machine time to do what your are doing. Do you have TP20 or TP200 ? Once you build the tips and calibrate, you are set, unless you unscrew something.

        Depending on where your programs reside, you can use global mark used and it will add the angles you need from all the programs with the probe file of that name.

        I could go on and on with many suggestions, but your way is not one of them, sorry.
        Jim Jewell

        Comment


        • #5
          Thanks Jim for the suggestions. The reason we are currently doing what we are doing is that we have had problems with tips going out of calibration because someone drops or bumps one, or even breaks one down, and doesn't tell anyone about it. We run 3 shifts, 7 days a week, so lots of time when no supervisors or senior people here to see whats happening. We felt our best bet is to calibrate on a bi-weekly schedule and if any odd results come up we will calibrate early just in case. Lots of wasted time, but nothing compared to what happens if a bunch of parts get inspected with an out-of-cal tip. We had that happen once before we started this schedule, managed to catch them all before any left the building, and don't ever want to risk that again.

          We do not have TP20 or 200. We are using TP6 probes with the autojoint.

          That "Global mark used" could be valuable once we get all of our programs transfered over to PC-DMIS. We are just beginning the switch this week from software we have been using for 10 years. We did not have an option like that in the previous software. Right now we are going at it backwards in that we will be transferring programs to PC-DMIS as needed so the tips will already need to be calibrated for any possible angles we need. Otherwise we would have to do a new calibration every time we transfer a program to add any necessary angles that haven't already been calibrated. I would guess that we are pretty darn close to using all available tip angles on the two tip builds in question so it might not make too much difference.

          I'm still trying to understand if what I'm suggesting in my original post will even work at all, never mind how efficient a use of time it is. I can't just go try it out because it will take a full shift to create the error map and I'll get my head chopped off if I take a machine out of production for 8 hours and have nothing to show for it.

          Has anyone ever used this feature on a PH10?
          2013MR1 SP6
          Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

          Comment


          • #6
            ALL it will do is 'tweak' the default angles (45,-90) to actual head angles (45.019,-89.582) to allow a DCC calibration to work without crashing the probe due to the head being mis-aligned.
            And I'm sure we don't need that, as we already run full DCC calibrations without any trouble. So thank you everyone for saving me a huge chunk of wasted time followed by bitter disappointment. As James recommended, we'll stick with what we're doing.
            2013MR1 SP6
            Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

            Comment


            • #7
              OK, not trying to beat a dead horse here, just trying to understand where the error comes from:

              - If ALL possible angles in the head are precisely mapped....
              - And a particular tip build is calibrated at enough angles (~12) that its geometry is precisely calculated....
              - Why can't the computer calculate the balance of the angles? Where would the error come from?
              - I could see some error from gravity if the tip is long an heavy. Where else?
              2013MR1 SP6
              Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

              Comment


              • #8
                Originally posted by DaSalo View Post
                Is it possible to use the "Calibrate the unite"?
                Of course it is but stay away from this area & get measuring.

                - Use "calibrate the unit" to generate an error map of PH10 by measuring the "T" configured tip at all possible rotation angles.
                If your Cmm has been calibrated right it already has enough error mapping to be going on with.......DO NOT give the software any more variables to think out about. Do you realise the errors you are talking about are in the realm of 0.00002mm (Renishaw figures) unless as stated earlier the 'Plate' has been bent by an occurence of which you know nothing?

                - Load one of our multi-purpose tip builds and calibrate a dozen commonly used angles through the range of the device with the "use unit cal data" box checked.
                - Run a qualification check using three of the physically qualified angles and 3 of the angles that would be calculated from the error map data.
                - If everything checks out feel confident that I can use this tip build at any angle even though I have only physically calibrated a dozen of them.
                - repeat tip calibration once a week. Repeat wrist mapping once every 3 months.
                All this shenanigans comes under the heading of 'Overkill' because I suspect lack of confidence elsewhere.

                We currently calibrate EVERY angle on two our tip builds once every two weeks (we alternate weeks so each build gets calibrated every other week) We need to do this for two different machines so it adds up to a lot of calibration time. We have to do this because we have hundreds of programs dating back over 10 years that use these same tip builds and each program could potentially use a dozen angles or more. To be sure we are ready for whatever comes along we calibrate every angle. This takes a long time so there is strong incentive for people to forget. If we can reduce the time for calibration it will get done more often. Even if the error map isn't quite as accurate as calibrating each angle physically the increased frequency of physical calibration on our more commonly used angles will offset this risk.
                You must use the KISS principle a lot more & get back to measuring accurately & with confidence that you can demonstrate.

                That's my thinking. Please poke as many holes in the logic as you can find. Thanks, Jeff
                As Jimminy 'Cricket' Jewell says in essence WHY??

                I too have access to tons of programs & where possible they 'borrow' probe builds from other programs to run if there is a'shared' commonality between probe builds. No point in re-inventing the wheel.......is there?

                Having said that, in principle each Cmm program has its own probe build @ the front of the program for use on that day with that batch or that 1st Off by that operator & not relying on the software to cover the variables with 'Marked Sets'.

                Everyone who uses the Cmm is responsible for the results that are then generated, saved, archived & decisions made on those results.

                We all know something might be 'NOT OK' but it might still be acceptable. This is where the probe calibration on that day with that batch & by that operator come to the fore. With other strategies you run the risk of having the customer stood behind you & you have your trousers down round your ankles.

                Not Good. In my case NOT a pretty sight so I do everything in my power to prevent it occuring. Especially with the likes of 'Ironhoe' & others on the same planet........they know who they are.

                I could not TRUST generated results based on the attempts of others to calibrate the probe right & then walk off & leave it in a fit state for me to use. Keep the variables to a minimum. The software itself will find variables you never even thought of without any interference from outside.

                All the time the probe is 'poncing' around the sphere it sure as h**ll is not measuring anything except LOST TIME.

                As Sheldon would say.........."Your'e welcome".
                Poleaxe

                Beware the environment you live in for it will shape you
                Be careful the friends you choose for you will become like them.

                sigpic

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                • #9
                  Thanks for the help everyone.
                  2013MR1 SP6
                  Global Frames, Tesastar-M Heads, LSP-X1M/H Probes

                  Comment

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