Mechanical drawing; a treatise on the drawing of mechanical and machine details (1920)
Jones, Franklin Day, 1879-1967 · New York, The Industrial press; [etc., etc.] · leaf 68
long holes containing metal bushings that fit closelyunder the screw-heads and yet allow the screws to move freelyin case the board contracts. Grooves are sunk in the board INSTRUMENTS AND MATERIALS 55 on the under side. These grooves take the transverse strengthout of the wood to allow it to be… … Fig. 28. Drawing-board equipped with Parallel Attachment into one end of the board. The strip is sawed apart at aboutevery inch to allow for contraction of the board. Parallel Attachment for Drawing-boards. — Some drawing-boards and tables intended especially for drafting are pro-vided with what is…
Mechanical drawing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten20unit-737-340.webp)
