Screw Gauge Pitch: Length of Main Scale Division?

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Discussion Overview

The discussion revolves around the concept of pitch in screw gauges, specifically whether the pitch is equivalent to the length of one main scale division. Participants explore definitions and applications related to screw gauges, including micrometers and thread gauges.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that the pitch is the distance traveled in one rotation of the screw gauge.
  • Others question whether the pitch is equal to the length of one main scale division, suggesting that this may depend on the type of screw gauge being discussed.
  • A participant notes that the pitch can be defined as the distance between consecutive threads on a single threaded screw.
  • There is a suggestion that the main scale divisions indicate the length of the jaw opening rather than the distance traveled, which may vary by gauge type.
  • One participant expresses uncertainty about the magnitude of linear displacement for one complete revolution and indicates a need to check manufacturer standards.
  • Another participant clarifies that the discussion is about a micrometer screw gauge, contrasting it with other types of gauges.
  • There is mention of the possibility that divisions on the main scale may correspond to the pitch in cases where a Vernier scale is present.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the pitch is equal to the length of one main scale division, and multiple competing views remain regarding the definitions and relationships between these measurements.

Contextual Notes

Participants express uncertainty about the specific types of screw gauges being referenced, and there are limitations in the clarity of definitions and assumptions regarding the relationship between pitch and main scale divisions.

gautam_cool88
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In a screw gauge, the pitch is defined as the distance traveled in one rotation. Is it also equal to the length of one main scale division?
If the length of one main scale division is not given, then can we take it to be equal to the pitch? Or do we take it as equal to some other default value.
 
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The pitch can also be thought of as the distance from peak to peak or crest to crest of adjacent threads. Now, when you say "one main scale division" what kind of thread gauge are you referring? I am used to seeing the types of gauges that you physically hold against a fastener to compare the thread engagement (similar to attached pics). What scale are you referring? It also helps to know what kind of screw thread type you are referring to.

480.1834.jpg

http://www.mcfeelys.com/images/prodimages/dg-0014.jpg
 
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hey i m talkin bout dis type of screw gauge.
 

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What is a 'main scale division' ? The pitch is the measured distance between two consecutive threads for a single threaded screw. Is that what you are asking?
 
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The screw gauge which I m talkin bout (image attached) has a circular scale and a main scale. By main scale division I mean the distance between two marks on a main scale.
 
I can't view your image yet. Pending approval.
 
Cyrus said:
I can't view your image yet. Pending approval.

I guess, your are right. Ridges of helix around a cylinder( as in screws) can give a linear movement for rotational movement. But, I am not sure about the magnitude of linear displacement for one complete revolution. I think it depends on the screw gauge. I will search for any generality or standard in the manufactures and comment again. Please oblige.

regards
shankara
 
What you have is a micrometer screw gauge, or just plain micrometer (as opposed to screw or thread gauge, which usually refers to the thing that FredGarvin posted):
http://en.wikipedia.org/wiki/Micrometer

If I understand your question correctly, then the main scale (and the Vernier as well) indicate the length of the jaw opening, and not the distance travelled--that's left up to you and/or your calculator, though I imagine that the digital ones (and probably some higher end mechanical ones) have this ability.

EDIT: I totally didn't answer your question (I'm posting this from my iPhone and couldn't see your original post). I'm not sure if my answer holds in general, but for all the ones I've seen, if there's a Vernier scale then the divisions on the main scale will be the pitch, since it takes one rotation of the dial to wrap the Vernier scale around and move from one division to the next.
 
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