Railroad machine screws

Model Railroader General Discussion (Model Railroader)
1

Hi

I’ve been looking for a source of 1/4 x 24 thread 2 or 3 inch long machine screws and nuts for a model railroad signal project. All the hardware stores and web sites I have looked at have only 1/4 x 20 or 1/4 x 28. These are the screw threads found on the old shelf relays, GRS Type K and US&S

DN11 and DN22 relays. Any ideas where I might find some. I would get at least 100. Thanks.

WGC53217

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WGC53217 - Welcome to trains.com! [C):-)]

3

McMaster-Carr has darn near any type of fastener you can dream up, I would check there.

–Randy

4

I checked there for him, and all I found were 1/4-20 and 1/4-28s. I would just buy the screws and a tap to match.

5

You might try 6mm x 1.0 according to this link from boltdepot.com.

http://www.boltdepot.com/Newsletter/Newsletter-2006-04.html

pav

6

Micro Fasteners at www.microfasteners.com has a lot of stuff. I see them at big train shows.

7

Last resort, try GRS or Ansaldo (US&S).

8

Poking around online turns up that old Harleys use them. So, they’re around. Somewhere.

Your mentioning of screws AND nuts leads me to wonder if you’re dealing with through bolts rather than tapped holes. If it’s through bolts, why not just use 1/4-20 or 28?

Ed

9

Okay, I’ll ask the painful question…are you sure that they are 1/4 X 24 thread? I looked at a number of on-line sites, including http://www.marfas.com/machinescrewtapping.shtml, and find no reference to a 1/4 X 24. I see 1/4 X 20, 1/4 X 28, and 1/4 X 32. I also looked in an engineering handbook and again see no reference to 1/4 X 24.

Although it is within the realm of possibility, I don’t believe that someone would have selected an odd-ball size for an American made product.

Edit: Well, okay, maybe with the exeception of Harley: http://www.flatlandmotorcyclecompany.com/1424-NS-x-2-Oval-Head-Machine-Screws-Parkerized-97122-Prodview.html

10

You may be looking for the wrong thing.

According to the UTS you are not going to find a 24 pitch screw in 1/4". You will find them as #10s and #16 in coarse threads and 5/16" and 3/8" in find threads.

I’m not sure where you got your measurement but you may actually have a 6mm screw which does come in a 24 pitch configuration. Six millimeters is close but no cigar; forcing a 1/4" screw into a 6mm hole will deform the hole slightly

11

Some biker is gonna be REALLY pi$$ed off when his seat falls off!!

12

WGC

I’ve never seen a 1/4-24 machine screw but that doesn’t mean that they might not have existed in the past. The two numbering systems are USS and SAE. United States Steel created as standard and are generally fine threads. SAE is Society of Automotive Engineers and are in the main the coarser options. SAE took this stance as there was so much gray cast parts in early autos that a fine thread would not work well in. I even found a hit for a 14-32 pitch screw but have never used such a thing and don’t know who’s standards they might be.

I’m wondering if you don’t have a metric bolt in front of you. I checked with my pitch gauges and a 1mm pitch is VERY close to 24 threads per inch. Further, the most common metric sizes are 6mm and 8mm diameters which are obviously some distance from one quarter inch.

BUT… there is a 7mm diameter size that is not common in automotive stuff that looks for all the world like a quarter inch. So I’m guessing that you have a 7x1mm bolt.

There are machine screw companies around the country. In the northwest of this country we have an outfit called Tacoma Screw that has local offices around the territory.

Call a local machine shop for assistance as the big box places seldom keep a decent selection of metrics and even less taps and dies.

see ya

Bob

13

I found a 1/4-24 nut:

http://www.grainger.com/Grainger/MIDWEST-ACORN-NUT-Acorn-Nut-4GVE9?Pid=search

and a bolt (though the flat head may be a problem):

http://www.chromebolt.com/1424-x-234-chrome-flat-head-bolt-p-461.html

Grainger also sells 1/4-24 taps and dies. If you can’t find the right bolt, you could run the die down a 1/4 inch steel rod and make your own. It wouldn’t have a lot of strength, but it’d fit.

So, again, why do you need both the bolt and the nut?

Ed

14

insert filler here

15

HI

Thanks to everyone who responded. I have tried several suggestions and still not found any. I

wanted to make my own terminal board using the same size and pitch screws found on railroad

shelf relays. Since these have been around for almost 100 years, I’m sure they are NOT metric.,

but actually 1/4 x 24. I suppose I’ll have to use standard screws instead. Thanks again for

trying to help.

Carl

16

These are a special thread used on RAILROAD SIGNAL equipment. As far as I know you have to get them from the manufacters of buss bars and signal items,