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brass coupler pocket screw(s)


Anthony Thompson <thompson@...>
 

Does anyone know the metric screw size of the standard coupler pocket screw in brass HO freight cars? I recently picked up some of these cars second-hand and the previous owner lost or harvested the screws. I do of course have some other cars which can furnish examples, but don't have a metric thread checker. Thanks in advance.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history


Kurt Laughlin <fleeta@...>
 

Do you have a micrometer (english or metric) that you could use to check the diameter of the thread on a mating screw? This diameter will always be slightly smaller than the nominal thread diameter.

Also, place a metric rule along the thread and determine the distance between thread crests (the wavelength, for the scientifically inclined). If very fine, measure distance of 10 crests and divide by 10.

There are a limited number of combinations of diameter and pitch that are standard. You might be able to divine the right one here: http://www.mcmaster.com/#machine-screws/=418ow2
or post and I'll take a try.

I would NOT use a tap to check the internal thread. With small sizes there are usually several closely spaced sizes. It is easy to change the thread while "checking". A tap can be used with a scew to check pitch, however.

KL

----- Original Message -----
From: Anthony Thompson

Does anyone know the metric screw size of the standard coupler
pocket screw in brass HO freight cars? I recently picked up some of
these cars second-hand and the previous owner lost or harvested the
screws. I do of course have some other cars which can furnish
examples, but don't have a metric thread checker. Thanks in advance.


Ray Zeffert
 

Hi Tony
Metric thread of 1.4mm, should be available at NWSL and others.
Ray Z

--- In STMFC@..., Anthony Thompson <thompson@...> wrote:

Does anyone know the metric screw size of the standard coupler
pocket screw in brass HO freight cars? I recently picked up some of
these cars second-hand and the previous owner lost or harvested the
screws. I do of course have some other cars which can furnish
examples, but don't have a metric thread checker. Thanks in advance.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history


Anthony Thompson <thompson@...>
 

Metric thread of 1.4mm, should be available at NWSL and others.
Ray Z
Thanks, Ray. YEs, NWSL has a lot of metric fasteners. I take it that the 1.4 mm diam. screw with fine threads is normally 0.3 mm pitch, and I can just choose the length.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history


Anthony Thompson <thompson@...>
 

I wrote:

I take it that the 1.4 mm diam. screw with fine threads is normally 0.3 mm pitch . . .
This is a coarse pitch thread (NOT fine), which is normally the default in metric threads. My mistake.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history


Malcolm H. Houck
 

Does anyone know the metric screw size of the standard coupler
pocket screw in brass HO freight cars?

Tony,

Most are 1.4 mm screws........with varying head styles.

Mal Houck


Andy Sperandeo <asperandeo@...>
 

Hi Tony,

It's been a long time since I bought any brass freight cars, but the two screws on either side of the coupler pocket were usually 1.4mm, the same as on locomotives and passenger cars.

See you in Naperville,

Andy

Andy Sperandeo
Executive Editor
Model Railroader magazine
asperandeo@...
262-796-8776, ext. 461
FAX 262-796-1142