[R-390] Gear Chemistry

[Roger Ruszkowski]

Fellows,
Will some one smack a cam in a hardness tester and give us a number.
This will give us a range of likely alloys.
Maybe not, heat treating could be in the works.

I always though that looking in many receivers since the late 60's that the
metal was just a stock known machine alloy. It stamps into parts well and wears well for
a 100 years of use. Obviously the gear trains are not made of a pure soft brass.

Over in manufacturing, these gear trains are just more big clock parts.
By 1955 it was just the last end runs on some well used war materiel production machinery.
No body was building big clocks and analog bomber range finders and equipment of such ilk.

The gear trains of these receivers were the state of manufacturing art.

The need for cash resisters, type writers, bomb sights, artillery gun sights, and other special machinery had brought the underlying
industrial capability to a level where small production runs (500 units in the total order) were produced order after order and parts are truly replaceable and interchangeable. 

In 1966 I did not see 2016 on the horizon.
Vacuum tubes are the steam engines of electronic communication as we know it on the Internet.
The US military  transmitters and receivers were the Union Pacific Big Boys of their era.
Dinosaurs, all come and gone and now mythology. 
 

Why not just good old cartridge brass not exactly deemed good enough for casing brass but good enough 
to role in to sheets and stamp parts from. Recycle, recycle, recycle, This activity is not a new idea. 

Respectfully,

Roger Ruszkowski

 
 
-----Original Message-----
From: Glenn Scott via R-390 <r-390 at mailman.qth.net>
To: r-390 <r-390 at mailman.qth.net>
Sent: Sat, Dec 10, 2016 8:26 pm
Subject: [R-390] R390 Gear Chemistry

Thanks Bob and Charles.. 


Not being a chemist, I didn't know what the composition was but I have heard those gears called brass and bronze interchangeably for decades;  I was just curious based on my experiences with brass.
The info Charles gave regarding the material may be 360-Brass seems to be a good choice/answer. I did some reading from a google search and found the following link and this seems like the best description of what  those gear actually be made of.


https://www.speedymetals.com/information/material13.html


My experience over the years with brass has been, it's somewhat soft and I questioned its use as a gear, especially, in receivers that have survived well after 5 decades. My brass experience was obviously using a different alloy of Cu and Zn. And perhaps the slight attraction to a Neodymium magnet was possibly due to the fraction of 1% of Fe. Since brass can be alloyed numerous ways, Bob's comments were also VERY helpful.. 


Not that anyone probably cares too much, but perhaps someone should make a note in the Pearls Of Wisdom Files regarding 360-Brass. Perhaps some other future R390A and/or (Non A) enthusiast may be curious.  Maybe that same alloy was used in the 75A, 51J and R388 series receivers as well.


One thing that's great about this list is, generally, any reasonable question sent up the proverbial Flagpole is usually met with kind, competent, knowledge and or experiences from many of the exceptionally bright people who frequent here.


Thanks and 73,


Glenn Scott WA4AOS
DSM Labs
864 684 2956

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