The blanks are first cut out of cold sheet steel, thereby avoiding the expense of heating them. They are then placed between dies which have been previously made to form the required design and shape, but are not as a rule completely struck up or formed at one operation, the minimum number of operations necessary to form the complete article being one or two, and the maximum being from five to seven. The parts are often annealed between the operations, as the pressure has a tendency to harden the metal.
REMINGTON
FLUSH JOINT.
The makers and users of sheet steel parts claim for them as advantages over drop forgings that they are of uniform size, shape and gauge; that they weigh less; that there is but little waste of material, and that as many as ten thousand operations can be done by one operator in a day. Of course, the cost of production is thus made lower as compared with the cost of production of drop forgings, which require a large amount of machining on lathes and other milling machines, necessarily slow in operation. The makers of these stamped form-drawn parts claim that through the largely increased use of their goods American makers have been able to produce lighter bicycles than they were formerly able to produce with the use of drop forgings for their connections, that the popularity of the bicycle in this country is due to the present popular prices at which they are sold, and that these popular prices are largely due to the low cost of sheet metal parts. They also claim that after the sheet metal parts and the tubes of the bicycle are brazed together, they then form one continuous piece, to all intents and purposes as good as if a solid drop forging were used. The average thickness of the sheet steel used in making these stampings is from 1⁄16 to ⅛ of an inch. Some very remarkable forms are produced in steel stampings, notably a crank-hanger of 2 inches in diameter, having two projections or lugs to carry the rear forks, and the two outer projections or lugs to carry the large lower main tubes and the large diagonal stay of the bicycle frame.
CRESCENT SHEET STEEL PARTS.
Until the cycle show of 1895 but little else had been heard of for making frame connections except drop forgings, but a revelation was placed before the eyes of the master mechanics of rival cycle making concerns who visited the show when they inspected the ’95 models of the Crescent, made by the Western Wheel Works of Chicago. Here were shown for the first time steering head connections, crank-hanger, seat pillar and rear fork ends all made of sheet steel and brought to perfection by a combination of the methods of stamping, drawing and forming. But even these parts did not surprise these experts of the trade so much as a sprocket wheel shown. Here was a sprocket wheel struck up out of a flat disk of sheet steel, its edge turned and drawn over, thus doubling the width of its face, and on this double edge were afterward milled the teeth. Of course, the parts shown in those days conformed in general outline to the construction then in vogue. The Crescent people, however, have continued to use this method of making frame connections; and while a large number of other makers have adopted this form of construction, they, as the pioneers of it, are still the leaders. Their production is enormous, their gross sales last year being 83,000 bicycles, and certainly if this method of making frame connections were not closely akin to absolute perfection their troubles under the guarantee would be enormous, and would swamp them. This year their frame connections are all of the flush joint style. The head connections are formed out of sheet steel reinforcements, having a large bearing and brazing surface.
Their crown is formed of two pieces of sheet steel drawn to a hollow arch shape. These two pieces are placed together and the ends come into a spearhead of capital letter A shape, two holes being drilled on each side in order to allow the brazing spelter to flow through the crown freely when the forksides are brazed to them. Before these forksides are brazed to the crown, however, a third piece of arch shape steel is forced down over the two pieces forming the crown. This third piece of sheet steel is lapped underneath the bottom of the crown, so that when the three pieces are brazed together they practically form one continuous piece. A drawn lug projects over the top of the crown, and into this the fork stem, the end of which is shaped to conform, is set on top of the crown and pinned and brazed to the lug and crown.
Inside of this fork stem, in order to strengthen it, is also placed a sheet steel liner, extending six inches into the length of the stem. The whole construction of this fork crown and stem is one of the strongest in use.
A test made of this form of fork construction at their works showed that by supporting it horizontally on a frame, the supports being about six inches above and below the crown, it sustained a weight of 3,500 pounds without deflection.