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Hardwood Record — Veneer & Panel Section 



August 25, 1918 



HUDDLESTON-MARSH 

 MAHOGANY COMPANY 



Importers and Manufacturers of 



MAHOGANY 



Lumber and Veneer 



2256 LUMBER STREET 



Chicago, Illinois 



347 MADISON AVENUE 



New York City, N.Y. 



The Curtis Machine Corporation, Jamestown, N. Y., 

 manufactures several models of propeller machines which 

 will cut four single blades at once from one master pat- 

 tern. The larger model cuts one side of the blade com- 

 plete before reversing, and four-bladed propellers can be 

 cut as well as the two-bladed. It is operated on the pan- 

 tagraph copying principle. The propellers are attached 

 along a vertical rack, two above and two below the orig- 

 inal or model, and the cutter spindles move in response 

 to a guide which follows the model. The spindles run 

 at a speed of 9000 revolutions per minute, and the cutters 

 are so constructed as to give a combination of a bore 

 and spiral cut. It is claimed that this machine leaves the 

 blades particularly smooth, thus eliminating the amount 

 of hand work necessary. 



After the propellers come from the machines it is con- 

 sidered good practice to hang them in a closed room of 

 uniform temperature from ten days to two weeks to allow 

 the moisture content of the wood to become uniform 

 throughout and thus eliminate strains and prevent sub- 

 sequent changes in balance. TTie treatment at this stage 

 has not been standardized, but tests are under way to 

 determine the best method to pursue. 



From this room the propellers go to the hand-finishing 

 room where they are carefully worked down to size and 

 shape by means of planes, scrapers and sandpaper. Cer- 

 tain points, called stations, are measured off along the 

 blade from the center of the hub, and the shape of the 

 blade at these stations must conform to the specifications 

 All Three of Us Will Be Benefited if 



and is governed by templates. The first work is done 

 at the stations, after which the surplus wood between is 

 removed. Especial care must be taken not to get the 

 work under size or the blades too thin at any point and 

 consequently a slight oversize is permitted. 



As this hand work nears completion the propellers are 

 repeatedly tested for balance, the object being to get 

 them so well balanced that when they are set up ver- 

 tically in a special rack they will stand still in any posi- 

 tion and yet move when a weight scarcely more than that 

 of a cigarette paper is added to one tip. Often this 

 result can only be obtained after hours of the most pains- 

 taking effort and the slightest change in the distribution 

 of the moisture content may upset it. Any wood while in 

 the "white" or natural condition is very sensitive to 

 changes in the humidity of the atmosphere and may not 

 only get out of balance but also undergo change in shape. 

 The propellers next go to the finishing room, where 

 they receive as fine a finish as the most valuable piano. 

 A filler, a primer, and five coats of varnish are given to 

 some of them, each being rubbed down after drying. 

 The training propellers have the ends copper-tipped. This 

 is put on in two thin sheets overlapping at the edges and 

 extending farthest along the cutting edge of the blade. 

 This copper is made as smooth as possible, then riveted 

 securely and the heads of the rivets and the edges sol- 

 dered and smoothed down. At the ends are punched 

 a few small drain holes. It is not now the practice to 

 copper-tip the combat types as in riveting the copper 

 You Mention HARDWOOD RECORD 



