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GAGING
C
UNEVEN SURFACES
0
HE foregoing sketches have not
OF
0
shown the uneven profile and
T
ragged surfaces that are to be
found in the shadow of the thread
of the average screw.
We must recognize these ele-
ments and decide on the character
of the work that will be acceptable.
Having determined the character of work, it is a
very simple matter to make a chart having boundaries
that fit our needs.
Let us remember that there is seldom a full thread
in the nut or the threaded hole. Hence we can tolerate
a slight rounding of the bottom of valley of the thread
profile. This rounding seems unavoidable in the aver-
age practice. It is due to the wearing of cutting dies
and also to the cutting process which does not leave a
true form of the cutting edge.
In other systems of gaging, the effect of the lead
error has been given more or less consideration.
It has undoubtedly been overemphasized in some
of our specifications for soft screws and nuts, and it
is equally true that it has been wofully disregarded in
important machinery.
The threaded ring gage, having a length approxi-
mating the thickness of nut or the length of engage-
ment of screw in the threaded hole, has not given us
the essential information. It has not told us where the
screw touched the gage.
29
Document source description
This is a publication about a comparator machine for the inspection of screw threads, with illustrations by Russell W. Porter.
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- photo
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- 0f17bf85143c1b04
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Document data
- ID
- 7077469
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Context sent to Scholar
Document identity
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{
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Page context
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"ocrText": "GAGING\nC\nUNEVEN SURFACES\n0\nHE foregoing sketches have not\nOF\n0\nshown the uneven profile and\nT\nragged surfaces that are to be\nfound in the shadow of the thread\nof the average screw.\nWe must recognize these ele-\nments and decide on the character\nof the work that will be acceptable.\nHaving determined the character of work, it is a\nvery simple matter to make a chart having boundaries\nthat fit our needs.\nLet us remember that there is seldom a full thread\nin the nut or the threaded hole. Hence we can tolerate\na slight rounding of the bottom of valley of the thread\nprofile. This rounding seems unavoidable in the aver-\nage practice. It is due to the wearing of cutting dies\nand also to the cutting process which does not leave a\ntrue form of the cutting edge.\nIn other systems of gaging, the effect of the lead\nerror has been given more or less consideration.\nIt has undoubtedly been overemphasized in some\nof our specifications for soft screws and nuts, and it\nis equally true that it has been wofully disregarded in\nimportant machinery.\nThe threaded ring gage, having a length approxi-\nmating the thickness of nut or the length of engage-\nment of screw in the threaded hole, has not given us\nthe essential information. It has not told us where the\nscrew touched the gage.\n29"
}