Author Topic: Small Screw  (Read 1069 times)

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sd75i

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Small Screw
« on: August 24, 2019, 09:23:35 PM »
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 I am looking for help finding some of these or maybe the right name for them?  Slotted shoulder screw??

u18b

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Re: Small Screw
« Reply #1 on: August 24, 2019, 09:33:43 PM »
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Looks like the drawbar or coupler screw to some brass locomotives or passenger cars.

Or is it a truck or tender screw?
Ron Bearden
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garethashenden

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Re: Small Screw
« Reply #2 on: August 24, 2019, 09:41:40 PM »
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Slotted shoulder screw is a good description. Here are a bunch: https://www.mcmaster.com/shoulder-screws

sd75i

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Re: Small Screw
« Reply #3 on: August 24, 2019, 10:35:08 PM »
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  It holds the track cleaning pad on a roco track cleaning car.

kornellred

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Re: Small Screw
« Reply #4 on: August 24, 2019, 10:44:25 PM »
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This type of screw fastens Samhongsa trucks to brass diesel chassis when used with a washer and spring.

narrowminded

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Re: Small Screw
« Reply #5 on: August 24, 2019, 10:46:07 PM »
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Do you have the actual screw dimensions?  One possibility to make up your own might be a piece of tubing on a standard screw.
Mark G.

bbussey

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Re: Small Screw
« Reply #6 on: August 25, 2019, 09:18:41 AM »
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If it’s from a Roco item, it’s probably a metric machine screw. Measuring the diameter and length in millimeters will get you the basic fastener designation — M{diameter}x{length} — and then tubing can be used for the shoulder as suggested above.
Bryan Busséy
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UP4-8-8-4

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sd75i

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Re: Small Screw
« Reply #8 on: August 25, 2019, 01:08:23 PM »
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  This is best I could do.  I do like the idea of tubing over it!  I used a micrometer for measurements. 

mmagliaro

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Re: Small Screw
« Reply #9 on: August 25, 2019, 04:35:11 PM »
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If I read your measured drawing correctly, the diameter across the threads is 2.86mm.  If that's right, then it is most likely an M3 screw.

These are not hard to find.  If you don't have an assortment of metric screws and nuts at home, you can take one to your local hardware store, like an Ace - they have metric screws that small and they have the nuts to match.  You can play with the sizes in the box at the store until you confirm what nut smoothly threads on to your screw.  If you don't have any of the screws, just the car, then take the car to the store and test with some M3 or M2.5 screws until you make sure of the thread.  There are different thread pitches for these, so be aware.  Hardware stores usually list them as "fine", "standard" and "coarse" or something like that.  You could have an M3 "fine" or an M3 "standard", for example.  You will have to just test your screw on nuts in the store. to figure out what you have.



narrowminded

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Re: Small Screw
« Reply #10 on: August 25, 2019, 07:14:27 PM »
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If I read your measured drawing correctly, the diameter across the threads is 2.86mm.  If that's right, then it is most likely an M3 screw.

I'm reading the 2.86mm dimension as the barrel diameter with the thread being 1.89mm or at the lower end of spec for a 2mm thread.  Thread pitch still up for grabs.  If you can get your hands on a thread gauge you could get the answer for sure.  Even a lot of mechanics will have one of those. 
Mark G.

mmagliaro

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Re: Small Screw
« Reply #11 on: August 26, 2019, 06:37:33 PM »
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Oh yes... I see now.... That 2.86 is supposed to be around the shank.  I thought it was the diameter across the threads and the 1.89 was the inner diameter of the threaded part.  But that would be kind of hard to measure, eh?   ;)  Okay... so probably M2. 

A quick stock check online shows that Home Depot carries those.  Ace only lists M4 and larger.
So it will depend on what hardware stores are handy to you if you don't want to go online.

sd75i

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Re: Small Screw
« Reply #12 on: August 26, 2019, 11:58:42 PM »
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  I will check HD when I get back in town!

bbussey

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Re: Small Screw
« Reply #13 on: August 27, 2019, 10:22:15 AM »
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Looks like M2x12.  Amazon carries a large variety of micro metric screws at a good price with fast delivery.  Search for the manufacturer Uxcell.
Bryan Busséy
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MK

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Re: Small Screw
« Reply #14 on: August 27, 2019, 04:57:25 PM »
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IF there is a LHS near you that carrys R/C airplanes and cars, they typically use metric screws M3 and under.