Perpendicularity to make sure a threaded part sits flat to a sealing surface

[MrGearhead]

Problem: Cylinder about .75" thick has a "humidity indicator" with a 1.0" dia male thread going into the cylinder... The designers of the humidity indicator claim that it is made to a perp of +/- 1 deg perpendiculariy to its own central axis but that it "deforms" when torqued into place such that perpendicularity of the mating female thread in the cylinder is not terribly important to how the humidity indicator seals to the top of the cylinder it's getting screwed into.

Bottom line: I'd like to spec the 1.0" dia female thread going through the top of the cylinder with as tight a perpendicularity as practicible without making the cylindrical part cost an arm and a leg... Just something that's "good" and not uncontrolled.

Suggestions here?

 

[Heckler]

How about specifying PERPENDICULARITY for an axis at a projected height?

Heckler
Sr. Mechanical Engineer
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This post contains no political overtones or undertones for that matter and in no way represents the poster's political agenda.