[GreenKeys] Re: Hold down screws for the M28 or M35 typing unit

Mon, 24 Jun 2002 16:33:54 -0700

Reminds me of Western Electric, Ben.  WECO used 12-24 and 1/4-28 
machine screws for things in the central office.

Don

At 4:24 PM -0700 6/24/02, Don Robert House wrote:
>Thanks Ben,  You are absolutely correct.
>Don
>
>>Comment:  Teletype tended to use National Fine series threads. 
>>These have more threads per inch than you would expect in a screw 
>>from the hardware store.  For example, we all have tons of 
>>National Coarse (NC) #6-32 screws around.   But Teletype used a 
>>#6-40 NF series.  If the mounting screws are 1/4-32, that also is 
>>NF.  The usual screw at the hardware store is, I belive a 1/4-20 
>>thread.  I never heard why they used NF screws; I suspect it may 
>>have been to keep the screws from loosening under the constant 
>>vibration.
>>
>>So be careful to start any unknown screw gently with your fingers, 
>>and if it binds up, you may have a NC screw trying to go into a NF 
>>tapped hole.=
>>
>>Ben Stephens K9KOM=
>>

-- 
--------------------------------------------------------
Don Robert House
URL: http://www.nadcomm.org
email: [email protected]
email: [email protected]
email: [email protected]
email: [email protected]
email: [email protected]