[GreenKeys] Model 15 Typical Operational Bounds on the Range Finder

[Charles Days]

"These limits are affected by loop voltage, current, the data source, etc" I cleaned my machine in '85 and worked on the selector mechanism. It was a total disassembly done in groups, solvent used to dissolve the wax sludge from decomposed oil. The "spool" with the selector teeth was in good condition and no teeth worn. The swords were fine too. What I found was unequal tension from the leaf springs. I have all the measuring tools to reset those springs.

>From a tape in the TD which was also precisely aligned as well as timing checks with a scope, I got 5 and 95, there is a polar relay in the circuit that too was also precisely calibrated on a polar relay test set.

It is important that the signals used to test the range finder are on time and free of distortion, that the loop current be correct, 60 ma/120 v, (not the impulse type of low current). That source will help determine if the selector mechanism is set up correctly, Do not forget the worn bushings and lack of or improper lube not be used.

I was using Nye's oil at the time, however, I discovered that Nye's (general purpose) oil did not do well on my firearms in cold weather, it is not tolerant to temp changes and gets quite viscous at 20 deg F. The oil suggestions go 'round and round. Since '85 the use of synthetic is highly recommend as the machine can go from 65 F room to upwards to 90 F after running for a couple of hours, getting "loose as a goose" . meaning that thin film of oil on the selector leaf springs can add or subtract "grab" on the swords thus effect their timing. Thus lubing the selector needs an oil that maintains viscosity over a wide range.

Once that is achieved, the range finder can be set at 45 to 55 and the machine will tolerate a great deal of distortion before printing an error.

If I need to re-lube I am considering auto 0-20 synthetic, widely available and now running in my grandfather clock, a '72 Kieninger movement never rebuilt, keeps time 3 seconds/week

All the information I used to calibrate the 15/19 printer I found in the government manual. I did add a little "gut knowledge". There is much more on other latch and lever spacing and spring tensions to the printing part.

Good Luck!

Chas

WA1JFD
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