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Thread gauge for extremely small screws?

shrtrnd

Jan 15, 2010
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Does anyone know a manufacturer that makes a metal (not cheap plastic) thread gauge so I can identify my zillions of extremely small screws. Nothing I can find on Google IDs the super small threads. (I know there's a type of thread that is called 'super fine'. What I need is hopefully a thread gauge plate that can ID very, very small screws and their threads).
All I can find go down to size #1, and these screws are smaller than that.
I have plenty of small machine screws, but have no way right now of knowing what bolt size I need for them.
Thanks
 

Bluejets

Oct 5, 2014
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Cannot imagine it.
Sighting the thread guage is required to differentiate between thread pitches and if the screws are as small as you say, then would be almost impossible to see, let alone be able to place the guage on the screw thread accurately.
 

Delta Prime

Jul 29, 2020
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shrtrnd

Jan 15, 2010
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Thanks Bluejets & Delta Prime.
I used to work in a Standards Lab, and those guys used to pull their hair out trying to use an optical comparator to figure-out the size
and thread count of some of the screws I used to bring them for identification.
I'll take a look at McMaster-Carr and see if they might have what I want.
I worked electronics, the mechanical standards guys often came into play with some of our fastening hardware.
If I didn't have so many of these micro screws I wouldn't worry about them, .... but it's a heck of a waste to have
so many small machine screws, and no bolts to make use of them.
 

Minder

Apr 24, 2015
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I use only metric where possible, with M2 being the smallest, I don't think they come any smaller than m1.6.
Most of the world is Metric now.
 

Delta Prime

Jul 29, 2020
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Difficult to see the chart let alone the screws......!!:rolleyes:
I was worried about that.Thank You sir. How about a do-over, I'm claiming" Mulligan" always replace your divots.
information on machine screw sizes from size 000 to ½ inch diameter (past size 12, screws are called by their measurements in inches). Diameter is the nominal size of the screw, measured from the farthest points of the threads. Although there are several types of machine screw designations in the Unified Screw. Information on the two most commonly used types: UNF (Unified Fine) & UNC (Unified Coarse). Often screw sizes will also tell you the number of threads a screw has by adding a dash & the number of threads. A screw’s major diameter shows the screw’s diameter as measured from tip to tip of its threads, this particular chart included the minimum & maximum measurements a screw can be to be classified as that size. The pitch diameter is the average of the screw’s width between its threads & grooves. A screw’s tensile stress area is the thinnest part of the screw, in the grooves, where it is most likely to fail

photo_1693456744528.png
 

shrtrnd

Jan 15, 2010
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McMaster Carr doesn't have a thread gauge small enough for my screws. (Size 1 is as low as they go)
Delta Prime's chart is pretty interesting though. It looks to me like I probably have the screw size '0', and they are obviously fine threads.
Didn't know there was a screw size 'zero'. At least that gives me a starting point to try.
I can buy some size zero (fine thread) nuts, and see if they fit.
Thanks for the chart (that I never saw before), Delta Prime.
 

Delta Prime

Jul 29, 2020
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Sorry about that. These guys call it something else . Here's a little snippet.

The company sold ready-made screws, and issued a screw plate as a means of checking sizes. Much of the use of the series occurred when makers found it convenient to thread their own screws using the screws plate as a die

 
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