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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.
Parents
  • This is a bit complicated. Do you have autofeatures available in your version of PC-DMIS?

    I have autofeatures

    How thick is the sheet metal?

    The sheet metal is only .027 inch

    How big are the holes?

    Holes are about .5 inch


    What is the diameter of the cylinder?

    Part is about 120 inch in diameter. There is some curve to the holes and due to the size the depth of the surface can and does vary from part to part.


    Those last three are because I'm wondering if you can measure a circle at one level and have all of the hits land on the edge of the sheet metal. Sounds like maybe not.



    Thanks for all the replies. I don't think I can take good hits on the holes all the way around with a ball stylus. The edge will always be in or out ever so slightly and the results would always be skewed. I am a newbe to the PC-DMIS and probing world in general so you did loose me a little as I read through the posts.

    The part was previously probed on another machine without PC-DMIS and the hole could be aligned perpendicular to a shank probe stylus. It worked pretty well with this set-up...

    Still looking like the plugs will be my simpliest and possibly most robust solution.
Reply
  • This is a bit complicated. Do you have autofeatures available in your version of PC-DMIS?

    I have autofeatures

    How thick is the sheet metal?

    The sheet metal is only .027 inch

    How big are the holes?

    Holes are about .5 inch


    What is the diameter of the cylinder?

    Part is about 120 inch in diameter. There is some curve to the holes and due to the size the depth of the surface can and does vary from part to part.


    Those last three are because I'm wondering if you can measure a circle at one level and have all of the hits land on the edge of the sheet metal. Sounds like maybe not.



    Thanks for all the replies. I don't think I can take good hits on the holes all the way around with a ball stylus. The edge will always be in or out ever so slightly and the results would always be skewed. I am a newbe to the PC-DMIS and probing world in general so you did loose me a little as I read through the posts.

    The part was previously probed on another machine without PC-DMIS and the hole could be aligned perpendicular to a shank probe stylus. It worked pretty well with this set-up...

    Still looking like the plugs will be my simpliest and possibly most robust solution.
Children
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