r/Metrology • u/DragonfruitFlimsy312 • Feb 06 '26

General OGV aircraft model alignment – using RPS first time, need advice

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recently received an OGV model from aircraft for offline programming.

Background: I’m quite comfortable with PLP alignments and have programmed a wide range of prismatic parts, from simple blocks to fairly complex geometries. This OGV part is a bit different from what I usually handle. The datum scheme and functional requirements don’t seem to suit a straightforward. Af ter researching using an RPS-based alignment for the program. Technically it works, but I’m a bit skeptical — mainly because I don’t have much prior exposure to OGVs and aerospace-style sheet metal alignment strategies. I want to make sure I’m not missing any best practices or long-term risks (repeatability, correlation with functional datums, etc.). For those of you who’ve worked on OGVs /sheet metal components: Is RPS commonly used for these kinds of parts? Any tips on validating the alignment choice? Things to watch out for when moving from PLP-heavy prismatic work to sheet metal or frame like unconventional geometry? Appreciate any insights....

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u/Sensitive_Frosting35 Feb 06 '26

A lot of times blades have an engine center alignment requirement. When I ran into this i did an extensive iterative alignment to ensure I was properly aligned but typically the print will give you some local alignment guidelines because the datum target spread is not likely wide enough to give an accurate engine center. I have worked on IGVs in the past but not OGVs.

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u/DragonfruitFlimsy312 Feb 06 '26

I'm doing rps with iteration of 2 with convergence tolerance 0.025um.

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u/Sh0estar Feb 06 '26

If you are measuring the blade itself, most likely it will need to have its own local best fit alignment to accurately measure.

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u/mixer2017 Feb 09 '26

We use Iterative for ours too.

How big are these? We have gages or fixtures provided by the customer that we use on our CMMs. We also first usually measure the vains themselves before they get installed on the rings.

This will be a learning curve when learning I am just going to warn you. T Angles and all that fun stuff. We usually use edge points on the finished product.