Circle scans on cylinder crash after 2nd alignment

[[Ja...]]

It seems to me that every time I set up a cylinder by using circular scan paths (180 degrees), it scans fine on the first alignment. It starts on one side, scans to the other, then comes up and over, and scans the next path. It seems that on the 2nd alignment, after scanning the first circular path it will try to move down and under the cylinder, causing a collision.

Does anybody know what I am doing wrong on my end? I have to end up adding move points to force it to move near the start of each circular path.

Thank you.

[[No...]]

What do you mean by second alignment? Do you have a loop on the base alignment?
Have you checked if the alignment got flipped somehow? Under bad circumstances the alignment may get flipped upside down, leading to a collision in the second loop.

[[Da...]]

Try Blocking edges. It's in Plan / navigation menu . You can block the ( I assume ) Z- edges and the probe will not try to pass below the part.

[[Da...]]

Also, you might want to scan 178 degrees and start at 1 degree. 180 checking vertically sometimes thinks that going under is the shortest path, by limiting it a small amount, ( 1 degree) then over the top will be the shortest distance every time.

[[Ja...]]

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Norbert,

I have a loop on the base alignment. I did not investigate what was going on with the alignment, I simply added some move points to rectify the situation. I will eliminate the move points and determine whether the alignment is being flipped or not.

Thank you.

[[Ja...]]

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Is this feature dependent? In other words, if I block the -Z edge, will the program disable travel to that edge for all features or for any feature that I choose?

I like the idea of eliminating 2 degrees from the scan, I was wondering whether it was confused which was the shortest path. I will try to make my next scan this way and see if it changes anything.

Thank you.

[[No...]]

Blocking edges is a global setting, meaning it's used for all features.
Normally you shouldn't need to modify the edges under the part. Calypso is smart enough to avoid moving around the bottom of the part, even if you're intentionally using a flipped base alignment. The edges under the part are marked in bold and are blocked by default.

If your alignment doesn't get flipped, a smaller scanning angle is probably what you need. Within the same strategy Calypso tries to take the shortest way to the next strategy element. On a cylinder it usually follows the shortest circular path, but doesn't care for collisions on the way.

[[De...]]

If you are doing scans two scans of the top half of the diameter then Dave Scott's method is the way to go.

It tries to find the shortest path and since its 180 it decides either way is fine, by making it only scan 178 degrees 178 degees back to the beginning is always shorter than 182 degrees so it will always stay to the same side.

If this does not work, then your alignment is actually flipping 180 degrees, if this is happening it is likely due to using a 3D feature such as a cylinder for your planar rotation.

[[Ja...]]

Thanks to everyone that pitched in,

I will take a couple of degrees off of my cylinder scans to avoid this issue in the future and if that doesn't work, I will watch out for the alignment flipping.

[[Te...]]

Another way to avoid this and leave the scans at 180° is to scan clockwise then counter clockwise and repeat for as many scans as you want works like a charm. You just need to set the scan path to 1 change the start height and then play with the Start angle and angle range (+180 /-180). Any time I am scan OD's this is the method I use to avoid the chance of Calypso trying to drive through the part.