Von Platen, Storia del reame di Napoli dal 1414 al 1423 (1864).
Under the hanging but fixed horizontal plane, called the platen, which gave the necessary impress when screwed down by the aid of the movable bar.
Blaeu's improvement consisted of putting the spindle of the screw through a square block which was guided in the wooden frame, and from this block the platen was suspended by wires or cords.
This block gave a more rigid platen, and at the same time ensured a more equal motion to the screw when actuated by the bar-handle.
The staple was united at the top and bottom, but the neck and body were left open, the former for the mechanism and the latter for the platen and the bed when run in preparatory to taking the impression.
The platen was screwed on to the under surface of the spindle; the table or bed had slides underneath which moved in, and not on, ribs as in the older form of press, and was run in and out by means of strips of webbing fastened to each end and passed round a drum or wheel.
As the platen was very heavy the operator was assisted in raising it from the type-forme by a balance weight suspended upon a hooked lever at the back of the press.
This somewhat counterbalanced the weight of the platen, raised it after the impression had been taken, and brought the barhandle back again to its original position, ready for another pull.
An inclined piece of wedge-shaped steel, called the chill, to become perpendicular; in so doing the platen is forced down, and the impression takes place at the moment the chill is brought into a vertical position.
On the return of the bar the platen is raised by a spiral spring, placed in a box and fixed at the head of the press.
The platen is attached to the centre of the lever by a square bar of iron, and its vertical descent is assured by two projecting guides, one from each cheek; it is then raised from the type-forme, and the iron bar carried back by two levers - the one attached to and above the head and weighted with the eagle; the other behind the press, attached to the arm to which the coupling-bar is fixed, and which also has a weight at the end.
The other lays on the sheet to certain marks, runs the carriage in under the platen, and pulls the barhandle across to give the necessary impression.
Two other classes of presses of somewhat different design were largely in operation in the middle of the r9th century - the " double platen," which still printed only one side at each impression from each end, and the " perfecting machine," which was made with two large cylinders and printed from two typeformes placed on separate beds.
The double platen press was somewhat analogous to the hand-press, both the type beds and impressions being flat.
In length, and the platen itself, of very massive construction, was placed in the centre.
This platen had a perpendicular motion, being guided in grooves and worked by a connecting rod fixed to a cross beam and crank, which acquired its motion from the main shaft.
There were two type beds and two inking tables, which travelled backwards and forwards, and one platen only, situated in the middle of the machine, which in turn gave the needful impression as the type-formes passed underneath.
The sheets were laid or fed to certain marks between the frisket and tympan, and when these were closed together the carriage was propelled under the platen and the impression was given to that portion of the machine, while at the other end another sheet was being fed in ready to receive its impression in due course.
The cylinder press is able to produce generally quite as good work as the double platen, its speed is much greater, and it requires a smaller amount of power to drive it.
We shall deal with it more fully below in relation to the modern and more complicated class of machinery; and this also applies to the ordinary stop or single cylinder, and small platen machines, both of which have been in use many years, and are still in demand.
Small platen machines (worked by foot or tion power) used for the printing of cards, circulars and small jobbing or commercial work.
The small but useful platen machine (fig.
As its name implies, the type bed and impression platen are both flat surfaces as in the hand-press, but as they are self-inking and are easily driven, the average output is about moo copies per hour, and but one operator is required, whereas two men at a handpress can produce only 250 copies in the same time.
In design these platen presses usually consist of a square frame with a driving shaft fixed horizontally across the centre of it.
This shaft is attached to a large fly-wheel which gives impetus to the press when started and assists in carrying over the impression when the platen is in contact with the printing surface.
The type-forme is usually fixed in an almost vertical and stationary position, and it is the platen on which the sheet is laid which rises from the horizontal position to the vertical in order to give the necessary impact to produce a printed impression from the typeforme.
Practically this platen is, as it were, hinged at the off side, nearest the type bed, and its rise and fall is effected by the use of FIG.
- The Golding Jobber Platen two arms, one on each side Machi, of the platen, which derive ne an eccentric motion from cams geared in connexion with the shaft.
When the sheet is printed and the platen falls back to the horizontal the operator removes it with one hand and with the other lays on a fresh sheet.
The modern single or " stop " cylinder, quite different in construc- Wharfe= tion from the old single cylinder machines, largely suc dale" ceeded the double platen machine.
?l"?????W Platen Jobbing Machines.