Best way to measure to see if equally spaced

[[Ja...]]

I need to make sure the slots are equally spaced

20180618_115644 (1).jpg

[[Ma...]]

One way to do this is create secondary alignments rotated in increments of 22.5 degrees. Now program how you want to measure one slot. Now copy the slot measurement (it is easier if you group the slots). Open the new copied features and choose the alignment pull down, click on Keep Position. Change the alignment of the copied group to your next 22.5 degree alignment. it will move it to the next slot. Repeat for each slot.

Keep Position will move the features to the next slot. Message me with you email and I can send you a video of how to do it.

Mark

[[Jo...]]

No you don't. They won't be equally spaced. You need to make sure they meet their tolerance.

[[To...]]

Datum C is the center line of what feature?

[[Me...]]

Equally spaced with in what ? +/- 1/2 Degree ?

[[Aa...]]

My interpretation is that "Equally Spaced" is describing their basic position/orientation. Tolerance is in the position FCF.

As Tom said, what is C the centerline of? (That's why putting a datum feature label on a centerline has been banned in both ISO and ASME for about two decades...)

[[Ja...]]

Datum C is a pin hole on the side of the OD and the it just says 8 slots equally spaced. There is not tolerance listed that I can find anywhere. I have it set to do the TP and the TP is good.

[[Ri...]]

It's difficult to give a specific answer to this but for evaluation, my first inclination would be TP\Pattern Best Fit. To program machine moves, I would measure all the features necessary on one slot. Highlight all those features and right click, and create a Group. Highlight the Group and right click to select Pattern. Use Rotation Pattern for Scallops.

[[De...]]

Since all 8 slots are called out to the same rotational datum, you have assured they are within .003 True Position of their 'equally spaced' nominal true position in relation to the locational and rotational datum features that are specified in the datum reference frame.

If the true position is good on all 8 slots to the datum features then you have satisfied the callout.

Equally spaced is given as nominal positional information, not a seperate callout.

No part in real life will in fact be 'equally spaced' there is always some error, hence the allowable tolerance of .003 true position to B C

[[Aa...]]

Actually, the way this is drawn is far superior to the approach of putting +/- limits on the angles between the features. Position needs to be contolled, too. (Many designers forget that just because they draw things on a common centerline, it ain't necessarily so...) Functionally, position and orientation are related. This is reflected by the MMC used on the print.

[[Ri...]]

I worry about worst case position size differences slot to slot might create a "good" part that isn't functional. I am assuming that something is supposed to fit inside that form. Push the locations and sizes of the individual slots to their most inconvenient limits while remaining in tolerance for that individual slot and you might end up with a basket full of parts that won't assemble.

[[Aa...]]

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Actually, if it's toleranced correctly, that should not be the case. The idea behind MMC and MMB is ensuring assemblability. Of course, that does require the inspector to correctly implement the software in such a way that doesn't yield false positives. (I've seen on this forum promotion of some practices regarding adding bonus tolerances from MMB that would inevitably lead to false positives.) That, of course, is more easily done with software correctly and completely designed to handle such situations without special arm-wrestling.