How to Make Ready a Platten Letterpress Machine
Making ready the press and the form to be printed is the most important operation of the pressman. The process consists of adjusting the impression so that all parts of the form will be printed with a firm, even pressure. The principle of the makeready are similar for all types of printing presses, the open platen, the automatic platen, the flatbed, and the vertical cylinder press.
Bill has a question about how to begin makeready for the title page of his booklet. He summons his instructor who will demonstrate the operation. Remove the form from the galley and place it on the stone. Place the form slightly above center in the chase and remove the string. Place the furniture around the form to fill in the area between the form and the chase. Space is left at the top and right so that coins may be inserted. Coins are the metal devices which exert pressure on the form and hold it securely in the chase. Place reglets on both sides of each coin to protect the furniture. Be sure that all type is on its feet and that the printing surfaces are even. Tighten the coins slightly and plane the form. Exert additional pressure on the coins so that the type cannot move. Re-justification is necessary if the type is loose in the form.
Important parts of any platen press include the ink disc, platen, grippers, top and bottom bales, ink rollers, and top and bottom leveling screws. Packing is held on the platen by the bales. Save the gauge pins for the next job. Each job requires new makeready and packing which must be inserted to adjust the impression and provide an even amount of pressure over the entire printing surface. Corners of the new packing are cut off to avoid binding when clamped by the bales and to provide a tight packing and drawsheet. Lay the packing which consists of one sheet of Tympan paper and three sheets of book stock over a sharp edge and crease along the edge to make an even fold.
Place the crease at the bottom of the platen and close the bottom bale. Insert the pressboard under the packing. Be sure that the Tympan is drumhead tight. Close the top bale. Move the grippers out to the extreme edges of the platen to prevent their smashing type when the press is closed. Ink the press before seating the form in position. Place a dab of ink about the size of a pencil eraser on the lower left-hand side of the ink disc. Distribute the ink evenly over the disc and rollers.
Place the form in the press. Use care to avoid striking the typeface. Coins should usually be at the top and right. Pull an impression on the drawsheet. This impression is necessary so that the gauge pins can be positioned to hold the stock in correct relationship to the form. Extreme care used in aligning the margins will save the pressman time and eliminate many printing problems.
Draw lines on the Tympan to indicate where the gauge pins are to be placed.
Clean off the ink from the Tympan to avoid offset on the stock. The side gauge pin should be about one-third the distance from the bottom of the sheet. Insert the point of each gauge pin through the Tympan paper about three-sixteenth of an inch beyond the pencil line. Be sure to bring the point up through the paper about three-eighths of an inch from the first insertion.
Now the pin will stay in alignment. Using animation, let’s see how the gauge pin should be inserted in the Tympan sheet in order to be positioned correctly.
Pull an impression on a sheet of stock. Check the alignment with a line gauge.
Readjust the gauge pins if necessary and set them by tapping lightly with a press wrench. The first impression may be too heavy or too light in some areas. Makeready is necessary to complete adjustment of the impression. Packing may either be added or removed.
Stab through the stock into the packing. Stab marks provide accurate register points to align the makeready sheet in the packing.
Without moving the sheet, pull an impression. Indicate the makeready areas by circling the light spots.
Apply a small amount of paste to the back of the hand so it will be readily available. Apply a thin coating of paste alongside the circled area. Avoid placing paste directly on the printed impression. Lay tissue over the paste and smooth down. Cut away the excess tissue.
It may be necessary to build up the light impression areas with two or three layers of tissue.
After makeready has been completed, place the makeready sheet under the drawsheet and align with stab marks.
The makeready sheet is held in position by pasting it to a sheet of packing. Remove a sheet of packing to compensate for the addition of the makeready sheet.
Move the grippers to hold the sheet making sure that they clear the form and the gauge pins. After this is done, any number of sheets may be run.
To review, remove all of the old packing. Be sure to save the gauge pins. Recover the platen with new packing.
To avoid smashing the form, move the grippers to the extreme edges of the press. Distribute the ink evenly over the ink disc and rollers before inserting the form. Position the gauge pins accurately.
When stabbing, position the sheet carefully to the gauge pins. Do not let the sheet move.
Build up the light impression areas by carefully pasting tissue to the makeready sheet. Adjust the grippers to hold the stock securely on the platen. Be sure that the grippers clear the form and the gauge pins.
With makeready finished and the adjustments made, the job is ready to be run.