Double Hits in DCC Mode (Press operation makes tip shake) & Part Machine Setup

[CMM2020]

Hello fellow operators,

I'm new to this forum, have been running CMM for the last 2.5 years and have been learning as I go (hit the ground running).

I have a question with regards to my probe taking hits twice sometimes when the press is running shaking the buildings foundation.

When I have a program running in DCC should I be concerned about the double beeps in some areas or does the software compute a stable hit in DCC regardless of the vibrations?

Also, can someone clarify Part/Machine setup a little better. I have mostly been running programs that have already been written but when do we use Part/Machine setup? Is that something that is needed as well when switching between different CMMs when using the same programs?

Thank you for any help.

[brian.freeman]

Capture.PNGIf you are having vibrations from the bag press; I would recommend to not having the CMM running at that time. Errant hits will cause erroneous data into the measurement routine, thus bad data/measurements.
WE sometimes have this condition but I wait until the press stops then rum the program.

As for the part/machine setup, I use this to orient the part on the table to how I want the measure the part. When using this, you can change the axis of the 'part' to match the axis of the machine.
I.E. CAD +X = -Y machine
CAD +Y = +X machine
CAD +Z = +Z machine
And how far away from the table you want the part it sit (virtually). And you can 'adjust the part' in X, Y, Z axis also

[CMM2020]

Thank you Brian.

My understanding of Part Machine setup is that it only has to be done once at the beginning of writing a new program. You want to be sure that when you're creating the alignment for the program that your part machine axis are correct when you are picking up the fixture etc.

Once the alignment has been made and the program has been created with the work plane set, if the program ever moved from one cmm to a different oriented cmm, the only thing you would need to change are the approach angles for the hits correct?

As far as running layouts without the presses, that will never happen here as we are always running. The data seems consistent from layout to layout but sometimes I do hear the odd "double beep" and when reviewing that point compared to others it seems fairly consistent as well. Im presuming when it beeps twice it's taking the second beep as it's measurement or somehow computing both hits into 1 measurement?

[DAN_M]

Yes, you'll want the part square to the machine's axees (physically as well as your CAD).

Double beeping:
Means your CMM is touching the surface and is NOT registering the fact that it is taking a hit like it is supposed to. This ISN'T good, it means something isn't working correctly. I would make sure the TP20 module isn't damaged. Sometimes, the little balls on the bottom of the probe mod will pop up a little bit from how far they're supposed to be...very carefully place the mod ball side down on the granite and press them back down into place. You might actually feel a "click". Doing this has "saved" quite a few probe mods in my day. Regarding running at the same time as the presses, I get it, still doesn't change the fact that doing so CAN and most likely WILL at certain points effect your accuracy. I suppose that will be up to you to monitor and work with per your company's needs.

[Paul Sarrach]

Hello Programmer, I am a Programmer. A Operator is the ones who run our programs. And Programmers make the big bucks. Plus you deserve the title CMM Programmer because that is what we do,

Yes after the alignment is will correct itself. But there are many different reasons and good practice to do it before you start programming. What I do is load in my cad, I put the part on the CMM in the position that i am going to write the program to. Once I have that the very next thing I do is Save that View. I call it Top View. And then I recall that view into my program The reason being is that the next time you or anyone else runs that program you/they will always know how it is orientated on the CMM. . And hit save.

The very next step i always do is "Part setup" Why this is good practice is when you start programming the Probe will be in the angle as on the cmm. Yyou need and you can see that on the screen. And it can and will prevent future crashes plus give you the warm fuzzy feeling that every thing is ready to start program.

Do you understand what I am trying to get across?

[CMM2020]

Hi Dan,

I am aware of the little ball prongs on the TP20 module, they are all seated nicely. I believe they pop out like that if you have a hard crash straight down in A0B0?
As for the shaking, the cause is that my table is not seated on an air cushion, it's a very old machine. There is nothing I can do for that (there are pads under the feet already to try to diminish the shock).

Hi Paul,

Thank you for clearing up the operator vs programmer analogy, I do write my own programs but I am a novice compared to others.
I understand clearly what you are telling me. I usually put a comment at the beginning of the program explaining how to orient the fixture next time I run the program.

Ideal time to run CMM is obviously when presses are not running, but we are always running so there would be no CMM work done.

When I have some time I'll do a little mini study and beep the same surface point over and over again as press is running to see how it fluctuates vs presses not running.

Thanks for all your help guys.

[Paul Sarrach]

A study is a great idea. Always is.

i have been a programmer for 30 years. I also hit the floor running without training. Since I am a PcDmis Guru let this be known from this day forward that you are no longer a Novice but have worked your way up to Competent Programmer.


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