Barth's cutting speed slide rule
Datecirca 1910
Inventory Number1990-4-0013
ClassificationSlide Rule
Subject
Maker
Carl G. Barth
1860-1939
Associate Name
Frederick W. Taylor
1856-1915
Cultural Region
Place of Origin
Dimensions1.2 x 23.2 x 4.6 cm (1/2 x 9 1/8 x 1 13/16 in.)
Material
DescriptionWood rule with four slides, faced with off-white paper on top. The top and bottom slides are fixed; the second and third slides move to left and right.
Printed on the bottom edge of the top slide is a scale for "CLASS NUMBER OF MATERIAL," carrying values from 0 to 40. On the top edge of the second, moveable slide are two arrows pointing towards the top slide. The left-most arrow is labeled, "CAST IRON"; the right-most arrow is labeled, "STEEL."
On the bottom edge of the second, moveable slide is printed a scale for "CUTTING SPEED PER MIN.," with values ranging from 10' to 400'. The third, moveable slide is divided horizontally into sections for "STEEL" (on left), and "CAST IRON" (on right). In each section are two scales, stacked vertically. The top scale, for "FEED," carries values descending from 0.25'' to 0.01''. The bottom scale for, "DEPTH OF CUT," has values ranging from 1/32'' to 2''.
The fourth, fixed slide is likewise divided horizontally into sections for "STEEL" (on left), and "CAST IRON" (on right). In each section, the top edge of the slide is printed with a scale for "LIFE OF TOOL," carrying values descending from 2 HRS. to 10 MIN.5'' 0.01''
Printed on the bottom edge of the top slide is a scale for "CLASS NUMBER OF MATERIAL," carrying values from 0 to 40. On the top edge of the second, moveable slide are two arrows pointing towards the top slide. The left-most arrow is labeled, "CAST IRON"; the right-most arrow is labeled, "STEEL."
On the bottom edge of the second, moveable slide is printed a scale for "CUTTING SPEED PER MIN.," with values ranging from 10' to 400'. The third, moveable slide is divided horizontally into sections for "STEEL" (on left), and "CAST IRON" (on right). In each section are two scales, stacked vertically. The top scale, for "FEED," carries values descending from 0.25'' to 0.01''. The bottom scale for, "DEPTH OF CUT," has values ranging from 1/32'' to 2''.
The fourth, fixed slide is likewise divided horizontally into sections for "STEEL" (on left), and "CAST IRON" (on right). In each section, the top edge of the slide is printed with a scale for "LIFE OF TOOL," carrying values descending from 2 HRS. to 10 MIN.5'' 0.01''
In Collection(s)
Signedtop of second slide, on right: Carl G. Barth
Curatorial RemarksRecords indicate that Barth was working in Philadelphia at the time;
Identical in function to 1990-4-0004, 1990-4-0014, 1990-4-0015, 1990-4-0016 though of different dimensions.
FunctionFor determining the appropriate speed setting on a lathe or similar machine.
The user first moves the second slide to left or right such that the arrow labeled with the type of material to be cut aligns with the appropriate hardness class number (top slide). Next, he moves the third slight to left or right such that the appropriate value for depth of cut (using the left- or right-hand scale, depending on material type) aligns with the length of time for which he needs to be able to use the tool (bottom slide, left- or right-hand scale according to material type).
Finally, the user locates the appropriate feed value on the top edge of the third slide (using the left- or right-hand scale, depending on material type). The value on the speed scale (second slide) with which this coincides indicates the speed setting (in feet per minute) that he should use.
The user first moves the second slide to left or right such that the arrow labeled with the type of material to be cut aligns with the appropriate hardness class number (top slide). Next, he moves the third slight to left or right such that the appropriate value for depth of cut (using the left- or right-hand scale, depending on material type) aligns with the length of time for which he needs to be able to use the tool (bottom slide, left- or right-hand scale according to material type).
Finally, the user locates the appropriate feed value on the top edge of the third slide (using the left- or right-hand scale, depending on material type). The value on the speed scale (second slide) with which this coincides indicates the speed setting (in feet per minute) that he should use.
ProvenanceThe papers and slide rules of Carl G. Barth and his son, J. Christian Barth, were transferred to the Baker Library of the Harvard Business School by J. Christian Barth in 1961.
The slide rules were transferred from Harvard Business School to the Collection of Historical Instruments in 1980.
Historical AttributesThis is part of a set of slide rules for machine shops designed by Carl G. Barth under Frederick Winslow Taylor's system of scientific management. Given the characteristics of a particular machine and a depth of cut, for example, a shop manager could quickly calculate the most efficient speed and feed settings using one of Barth's speed and feed slide rules. Other objects in the collection include slide rules for helical springs, belts, and gears, as well as jigs for making slide rules.
Hemmi
Date: 1971
Accessories: brown leather case with glap closure; brown leather loop for attachment to belt
Object number: 1989-1-0009
