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CMM stuttering during linear open scans

Timbort
Hello,

Wondering if someone can help me. I amusing a star probe to scan a cylinder with a linear open. The probe seems to intermittently "stutter" during the scan and reports an error for workpiece lost contact. Wondering if anyone has had this issue and has any idea what might cause it.

The other thing is it seems to happen more in the morning after being unused all night but by the afternoon the problem largely clears up. Wondering if it is possibly something mechanical.

Thanks
  • You could change the max force in F10 (depends on the probe, add around 10-20%).
    You can also decrease the scan accel and the scan speed.
  • What scan type? Defined or relearn?

    What probe type (x1, x3, x5 sp25?)?

    How long are the horizontal extensions?

    Typically we'd recommend leaving the main opt probe settings as default, but you could make small increases to the scan offset force to see if that cures it. I can recommend values without knowing the sensor type.
  • there's a few things potentially going on here.
    1. the artifact you're checking is vibrating.
    2. the star probe you are using is vibrating because
    a. the star probe is long and not stable
    b. the angle you are using is to "unnormal" to the surface you're scanning
    c. the surface you are scanning is not smooth enough
    3. you are scanning too fast/slow
    4. the machine is cold and you need to cycle it a few times to get it warmed up. I have a quick 10minute program i run every morning where the machine just cycles around the table a few dozen times to stretch it's legs.
    5. did you use the scanRDV calibration method?

    good luck
  • Check out your Exec Controls settings. If it is set to RELEARN, the machine will dynamically adjust the scan path as it goes. This is great for reverse engineering something that you don't have a model for, but you need to slow your scanspeed down to get a smooth motion. The machine will have a much easier time of it if you set it for DEFINED.

    Another thing to consider is to use a Circle/Cylinder Scan or an Auto Circle/Cylinder set to Adaptive circle scan. Those essentially have a defined path built in.

    Otherwise, you can reduce the speed and acceleration settings. It is also possible that there is just something wrong with your machine. It is strange that the problem is inconsistent based on time of day.
  • Dear Esteemed Senior Members and lecherous others,

    Sounds like you have an outdated motherboard. Some controllers can't handle all of the information Pcdmis hands back to it, and the unit just seems to scan the air as if it was the part. Check your firmware Rev. and see if is sufficient for the most tarted-up version of the Demon Hexapimp is worshipping.
    The problem, I think can be reduced by rolling back your install?
    Or stop "scanning"?
    I mean, we built the space shuttle just fine without "scanning". So what's the big deal with '"scanning" all the time?
    I remember enjoying myself quite much, with point to point circles and smoking cigarettes in the quality lab and such.

    Bite the face off someone you love today.

    Sincerely,
    Gabriel Ortiz
    213-548-1953
    ​​​​​​
  • When was the last time you cleaned the ways and scales?
    I've also seen this type of behavior with a corrupt probe file.
  • in reply to BKulpa
    I've seen odd 'stuttering' when the probe is shanking. Since it is all based upon the contact being on the ball, the length and force at ball contact, if the contact isn't the ball, then it really does some weird stuff.
  • Have seen stutter/chattering when scanning anodised parts are your parts coated in anyway.
  • in reply to UKCMM
    Maybe a light coat of oil. That's what some of the Hexagon tech do when they perform the scan test on the ceramic ball.
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