The essentials of descriptive geometry . elopable draw the plan and elevation helicoid. The strings are each tangent to of a Convolute surface,the helix of which they fonn the envelope, DisCUSSion. A COnvoluteand which may be seen in the illustration. i i . IS usually represented by its base and the plan and elevation of the directing helix, and anumber of elements. Since the surface is generated by a linemoving tangent to the directing helix, it becomes necessary todraw a number of tangents to the helix and find where theypierce H or V to get the base. Construction. In Fig. 136, MN is the axi
The essentials of descriptive geometry . elopable draw the plan and elevation helicoid. The strings are each tangent to of a Convolute surface,the helix of which they fonn the envelope, DisCUSSion. A COnvoluteand which may be seen in the illustration. i i . IS usually represented by its base and the plan and elevation of the directing helix, and anumber of elements. Since the surface is generated by a linemoving tangent to the directing helix, it becomes necessary todraw a number of tangents to the helix and find where theypierce H or V to get the base. Construction. In Fig. 136, MN is the axis of the given helixABCD. By Article 130 draw a number of tangents to the helixand find where these tangents pierce H at i, 2, 3, 4, etc. Thecurve through these points will be the base in H. 136. In Fig. 137 is shown the plan and elevation of a con-veyor, whose flights are made developable helicoids. To drawthe plan and elevation of such a surface the diameter and pitchof the smaller helix — the directrix — must be known, and also. WARPED SURFACES 169 the length of the generatrix or the outside diameter of the con-veyor flights. Given these data the drawing is made as follows:Tangent to the directing helix at B draw AB. A is the pointwhere the line, which is a position of the generatrix parallel to
Size: 1596px × 1565px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192400462, bookyear1915
