SCANNING ISSUE.....dealing with the demon

[mcintyrej]

I am having an issue with my scan data coming out wavy. I have ran multiple tests to figure out what the problem could be...changed out the probing system, tried multiple stylist sizes, ran different programs to rule out model issues, ran different types of scans that cover all of the machine axes. I also tried changing the exec. control, same result for defined and relearn but normal probing seem to bring back the scan data uniformity. Also my Std.Dev. has jumped up, i normally see around .00001-.00002 across the board no matter what the angle or rotation. Now im getting around .00005-.00006, numbers have never been that high. Not sure if it could be in the controller or if belts could be getting bad. Has anyone encounter this before? Any help on this will be greatly appreciated

Thanks!

Machine: B&S Global 7.10.7

Software: PC-DMIS 2014.1

Probing System: Renishaw
PROBE.JPG







This is a reference from one program with how my data normally looks like compared to now.


NORMAL:

Scan_good.JPG

ISSUE:

Scan_Issue.JPG

[KIRBSTER269]

What's your Offset Force set at? .120 is usually a good setting for me. You can also set this in F10

Capture.JPGCapture1.JPG

[mcintyrej]

Offset force is set to .1; been set at that for years with no issues.

[KIRBSTER269]

That seems like a good number, that's just the force that the probe applies on the part..

[JEFMAN]

You should check the air bearings...
Just open the hoods, and check if they turn freely.

[RIDER]

Is there a burr bench running or something else that is sending vibrations into the machine?

[mcintyrej]

No, this is my machine i use to build programs and run gages for calibration purposes. Its located in our metrology lab.

[KIRBSTER269]

IMG_0778.JPGIMG_0777.JPG

Pull back the dust cover on the "Y" travel, Look where the belt is, check under that bearing and see if you have a pile of metal dust, If so probably needs new bearings everywhere, "Z" and "X" If You do this yourself, you should replace all twelve, it will be a chore. you can get these through McMaster-Carr for about 1.50 a piece. Now if Hexagon does it, If I remember correctly, those bearings are 35.00 a piece, plus labor. This project is not easy to do, so If you go cheap expect problems.

[mcintyrej]

Looked at that yesterday and did not see any issues there. Hexagon is coming in to service the machine. Ill update the thread with final verdict for future reference.
Thanks for your input!

[KIRBSTER269]

no problem, sometimes a little 3-1 oil on these bearings help. you know what, I can't remember its been awhile when I did this, there might be 4 bearings in each one, now that I think about it.

[louisd]

my guess is a dead board in your controller.

[louisd]

You don't by any chance have filtering or outlier removal turned on, do you? There's some known issues with changing variables within those settings that can contribute to inaccurate/wonky data.

My first plan of action would be to simplify your baseline. Scan a simple line or plane
-Second action would be to isolate the machine's drivetrain: scan that simple line or plane, oriented along each axis. See if it is only affected in one or two axis.
-If so, rotate your probe head B angle 90° and re-attempt. Does it follow the rotated probe head or stick with the machine coords?
-If you see no contributor to either of those, I would suspect your SP25M is going bad or there's some other issues with your sensor or calibration of it.

How do your probe calibrations look? How does form of your scanned cal sphere look?
How does form of your simple plane look if you take a ton of TTP hits on it?

Not so sure of the SP25M, but the "Probe enable" button on jogbox is a "Probe re-balance" on my leitz, and must be illuminated at all times while measuring. Is this the simple fix, turn on your probe enable button?

[edrake]

Did you get this sorted?

It looks a bit like a problem I had a few years ago. In that case, it was solved with a new Logo2 board

Here's a link to the topic I started on it:

https://www.pcdmisforum.com/forum/pc...rd-issue/page2

It has some pics I posted that look a bit like yours, but mine were wavy 'top and bottom' yet smooth on the sides (and I was scanning a XX ring gauge). if I rotated from A0B0 to A0B-90, the waviness went to the sides with smooth top and bottom'.

Thanks again to louisd, who recommended that last rotation - I was already trying it in A0B0, A90B180, and A90B-90, and getting the same wavy 'top and bottom' in every orientation which seemed to preclude it being a machine axis/travel problem...