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Creative suggestions on probing sheet metal

Im working with a gantry style machine and a large cylindrical part with a sheet metal section. In the sheet metal all the way around the circumference of the part are holes that I need to check positional accuracy of. I was going to use a shank type stylus but it appears that I'm limited to 5 degree incriments in PC-DMIS and this will not allow me to probe the holes at a perpendicular angle thus skewing their position left or right depending on the angle used...I've read in other posts just how much people dislike these styli for this very reason...

I can not probe the edges of the sheet metal with a normal ball type stylus without going to far in or out which also skews the results.

I've been told they've used plugs here in similar situations to allow for probing on a more substancial surface but I'm sure the accuracy of probing the plugs is also questionable. We'll probably be goin this route but I'd be curious if anyone had any thoughts. There is over 100 holes so thats alot of plugs to have made not to mention the amount of time lost during the installation and removal of the plugs for each part probed...

Wish I was able to calibrate and program the probe for all the crazy angles I'd need. Then I'd give the shank probe a try.
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  • It would seem to let you input 4 sample hits even though 3 is the largest number shown in the drop down.

    Here's one more issue that may complicate matters. Are the holes drilled/punched after the sheet is formed into a cylinder or before? One way you would have a nice round hole whose sides are all "pointed the same way". The other way, you might have more of an oval and the sides of the hole will be twisty.

    In addition to that will be the ability to pick a "real" circle from the cad data, no matter which way the holes are put in (PRE-FORM or POST-FORM). Pcdmis will only find a ROUND circle when it is on a 100% flat surface. you may have to have some CAD help to get the correct nominals for probing.
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  • It would seem to let you input 4 sample hits even though 3 is the largest number shown in the drop down.

    Here's one more issue that may complicate matters. Are the holes drilled/punched after the sheet is formed into a cylinder or before? One way you would have a nice round hole whose sides are all "pointed the same way". The other way, you might have more of an oval and the sides of the hole will be twisty.

    In addition to that will be the ability to pick a "real" circle from the cad data, no matter which way the holes are put in (PRE-FORM or POST-FORM). Pcdmis will only find a ROUND circle when it is on a 100% flat surface. you may have to have some CAD help to get the correct nominals for probing.
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