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vernIer cAlIpers

456 GeAr tootH vernIer cAlIpers for tool operAtIon:
20-2 DIAMETRAL PITCH a. Find on the chart, furnished with the tool, the number
of teeth of the gear in question, and find the corrected
addendum (s"). This figure is for one diametral pitch for
456M GeAr tootH vernIer cAlIpers
inch measure, so divide it by the diametral pitch number
1-1/4-25MM MODULE – this figure is also for a one millimeter module for metric
measure, so multiply it by the required module number.
The 456 Gear Tooth Vernier Caliper is designed to measure in .001" or 0.02mm
Slide CaliperS the thickness of gear teeth at the pitch line (the chordal thickness of the teeth) b. Next, measure the actual outside diameter of the gear
This gives a corrected addendum for this particular
number of teeth.
using the distance from the top of a tooth to the chord. For the same purpose, it
can also be used for measuring hobs, form and thread tools, etc.
and add or subtract one-half the difference between
The thickness of a tooth at the pitch line is measured by an adjustable jaw
the theoretical gear diameter and actual measured gear
after the addendum is set by the adjustable tongue. Each of these is adjusted
diameter from the corrected addendum (s") found in the
independently by screws on the graduated bars.
first step.
Graduation – .001"
Cat. No. EDP Range c. Set the new calculated addendum figure on the adjustable
456AZ 52420 20-2 Diametral Pitch tongue of the tool.
456A 52422
456BZ 52424 10-1 Diametral Pitch d. Now, with the tongue on the top of the tooth, measure
456B 52426 the chordal thickness with the horizontal vernier jaw and
Graduation – 0.02mm compare with the figure in the "t" column in the chart.
Cat. No. EDP Range e. All inch graduations are read to .001". However the
456MAZ 52421 1-1/4-12mm Module
456MA 52423 456A is graduated by .020" increments and the 456B is
456MBZ 52425 2-1/2-25mm Module graduated by .025" increments. 456MA and 456MB are
456MB 52427 read to 0.02mm and graduated by 0.5mm increments.
Available with carbide measuring surfaces on special order. Available with attractive, protective case – sent with
case unless otherwise ordered. Packed one in a box.

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