ASTM E210-63(2005)
(Specification)Standard Specification for Microscope Objective Thread
Standard Specification for Microscope Objective Thread
ABSTRACT
This specification covers the basic and design forms, lead, classification, and nominal size of the screw thread used for mounting the objective assembly to the body or lens turret of microscopes. It is based on, and intended to be interchangeable with, the screw thread introduced and adopted many years ago by the Royal Microscopical Society of Great Britain, generally known as the "RMS thread" and now almost universally accepted as the basic standard for microscope objective mountings.
SCOPE
1.1 This standard covers the screw thread used for mounting the objective assembly to the body or lens turret of microscopes. It is based on, and intended to be interchangeable with, the screw thread introduced and adopted many years ago by the Royal Microscopical Society of Great Britain, generally known as the "RMS thread" and now almost universally accepted as the basic standard for microscope objective mountings. Formal recognition, however, has been extremely limited.
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Designation: E210 – 63 (Reapproved 2005)
Standard Specification for
Microscope Objective Thread
This standard is issued under the fixed designation E210; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This Standard is American National Standard Microscope Objective Thread (ANSI B1.11–1958) as developed by American National
Standards Committee B1 on Standardization and Unification of Screw Threads under the sponsorship of The American Society of
Mechanical Engineers and the Society of Automotive Engineers. It is copyrighted by and is reprinted with the permission of the
publishers. The American Society of Mechanical Engineers, 345 East 47th St., New York, NY 10017.
GENERALAND HISTORICAL dard, however, the design thread form established inAmerican
War Standard ASA B1.6–1944, has been adopted.
1. Scope
5. Pitch Diameter Allowance and Tolerances
1.1 Thisstandardcoversthescrewthreadusedformounting
the objective assembly to the body or lens turret of micro- 5.1 The pitch diameter allowance and tolerances promul-
scopes. It is based on, and intended to be interchangeable with, gated in June 1924 for the RMS thread were subsequently
thescrewthreadintroducedandadoptedmanyyearsagobythe applied by most American manufacturers to their truncated
RoyalMicroscopicalSocietyofGreatBritain,generallyknown versions and found to be acceptable. Uniformity of practice
as the “RMS thread” and now almost universally accepted as with regard to the allowances and tolerances for the other
the basic standard for microscope objective mountings. Formal diameters never materialized.
recognition, however, has been extremely limited.
6. Attributes of Good Fit
2. Referenced Documents
6.1 Experience has established that the principal attributes
2.1 ASA Standard: of a good fit for microscope objective threads are:
ASA B1.6–1944 Truncated Whitworth Threads 6.1.1 Adequate clearance to afford protection against bind-
2.2 ANSI Standard: ing due to the presence of foreign particles or minor thread
B1.7–1949 Nomenclature, Definitions, and Letter Symbols crest damage.
for Screw Threads 6.1.2 Sufficient depth of thread engagement to assure secu-
rityintheshortlengthsofengagementcommonlyencountered.
3. Terminology
6.1.3 Allowances for limited eccentricities so that central-
3.1 The nomenclature, definitions, and letter symbols used ization and squareness of the objective are not influenced by
in this standard are in conformance with ANSI B1.7–1949.
such errors in manufacture.
4. Truncated Whitworth Thread 7. Need for Good Fit
4.1 Because of its British origin, the basic thread possesses
7.1 The need for the above characteristics stems principally
the British StandardWhitworth form, having an included angle from the inherent longevity of optical equipment and the
of 55° and rounded crests and roots. This same full Whitworth
repeated use to which objective threads are subjected. The
form is also employed as the design, or maximum material, measures necessary to provide these properties precluded
form by the British. The presence (American National) stan-
adoption of the allowances and tolerances recommended for
threads of this pitch in the American War Standard
ASA B1.6–1944. The more significant departures from the
This specification is under the jurisdiction of ASTM Committee E41 on
standard are:
Laboratory Apparatus and is the direct responsibility of Subcommittee E41.01 on
Apparatus. 7.1.1 A larger allowance on the pitch diameter of the
Current edition approved May 1, 2005. Published October 2005. Originally
external thread.
e1
approved in 1963. Last previous edition approved in 1999 as E210– 63 (1999) .
7.1.2 Smaller tolerances on the major diameter of the
DOI: 10.1520/E0210-63R05.
external thread and the minor diameter of the internal thread.
Discontinued 1951, Available from National Institute of Standards and Tech-
nology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070,
7.1.3 The provision of allowances on the major and minor
http://www.nist.gov.
diameters of the external thread.
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E210 – 63 (2005)
7.2 The values established and further details regarding 14. Allowances
them are given under Specifications.
14.1 Positive allowances (minimum clearances) are pro-
vided on the pitch, major, and minor diameters of the external
8. Other Applications
thread. The allowance on the pitch diameter is 0.0018 in., the
8.1 Though utilized principally for microscope objective
valueestablishedbytheBritishRoyalMicroscopicalSocietyin
mountings, this screw thread is recommended also for other
1924 and now widely regarded as a basic requirement. The
optical assemblies of microscopes and associated apparatus,
same allowance is also applied on both the major and minor
such as photomicrographic equipment.
diameters.
14.2 Where interchangeability with product having full-
SPECIFICATIONS
form Whitworth threads is not required, the allowances on the
9. Basic Form of Thread
major and minor diameters of the external thread are not
9.1 The basic form of the thread for this standard is the necessary, since the forms at the root and crest of the truncated
British Standard Whitworth form. Basic dimensions are given internal thread provide the desired clearances. In such cases,
in Table 1. either both limits or only the maximum limit of the major and
minor diameters may be increased by the amount of the
10. Design Form of Thread
allowance. Benefits are derived principally from changes in the
10.1 The design, or maximum material, forms of both the
major diameter where increasing both limits improves the
external and internal threads conform to the ASA B1.6–1944.
depth of thread engagement, and increasing only the maximum
The design dimensions are given in Table 1.
limit grants a larger manufacturing tolerance. However, unless
such deviations are specifically covered in purchase negotia-
11. Lead of Thread
tions, it is to be assumed that the threads will be supplied in
The thread is of the single (single-start) type.
accordance with the tables in this standard.
12. Classification
15. Tolerances
12.1 There is established herein only one class of thread
15.1 In accordance with standard practice, tolerances on the
which experience has proved to be adequate to meet the
internal thread are applied in a plus direction from the basic
demands of the applications.
(also design) size and tolerances on the external thread are
13. Nominal Sizes
applied in a minus direction from its design (maximum
13.1 There is only one nominal size having a basic major material) size.
15.2 The pitch diameter tolerances for the external and
diameter of 0.800 in. and a pitch of 0.027778 in. (36 threads
per in.). internal thread are the same and include both lead and angle
TABLE 1 Definitions, Formulas, Basic and Design Dimensions
Property Symbol Formula Dimension
Basic Thread
...
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