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0t--pitchometer---large format metrology


Oct 8, 2005
western washington state
so a NS Navy pitchometer touched down in my yard
I had no prior knowledge of this measuring devise--but uncovered factoids of interest

instrument illustrated was authorized by navy contract 1966
bespoke build--Germany

used in dimensioning propellors of surface and subsurface vessels
Farrand resolvers on x,y,z axes--cartesian coordinates

unit was employed in local naval yard --prop would be placed horizontal with tapered stub shaft
engaging complementary prop bore taper
the pitchometer would then be clamped onto stub shaft and balanced

look closely at slide presentation --an eight foot chrome tube is strapped to pallet--this is the stylus to
which attaches active probe used in contact measurement--stylus slides in rack/pinion bracket -vertical--
on tapered arm

3 phase vfd controls x and z axes--orbital axis is hand powered

overall length 25 ft
weight 3800 lb

counterbalance arm has sliding weight compensating for radial motion of probe apparatus--I severed this arm
to inspect construction
tapered arm will undergo similar amputation leaving a precision pivot with graduated ring and vernier for some other application

this unit likely served its purpose for 50 years--my guess is non-contact dimensioning is now in use for capital
ships with prop diameters up to mid 30 ft

Kappel geometry props now prevail in blue waters

hidden surprise in this saga is the 600 pound 20 inch 4 jaw concentric chuck attached to base of turntable--it is removed and
undergoing dissection

chuck was bespoke built by Buderus--boutique speciality steel provider
unique clamping system driven by worm and ring along outer circumference
more on this soon



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