OPERATING INSTRUCTIONS SOHN MODEL 6503
FLEXOGRAPHIC LABEL PRESS
To begin set-up of the Model 6503 Flexo Printer, refer to the threading diagram. There are three
configurations that can be used. Follow these instructions for proper results.
The next step would be to center the paper to maintain proper tracking. The center of the model
6503 machine is 4" from the back plate. An example would be when using 2" wide material, a mark should
be put on the center of the roll at 1" from either edge, place the roll on the unwind spindle with the paper
unwinding to the left from the top of the roll and measure 4" to the mark on the material from the back side
plate. The material now is centered on the machine. Next thread the material thru the machine, refer to
threading diagram. The spring loaded pacer assembly must be unlocked when threading. To unlock, pull
back on the assembly until the pin locks in the back side plate. Once you have the paper threaded, place the
blank core on the unwind, attach the material to the core. At this point, the measurement of 4" is again
applied. Next the paper guides are set both on the infeed and rewind, the 4" measurement again is applied.
Slide collars to edge of paper allowing approximately 1/64" clearance on either side. This will assure proper
tracking of materials. Run machine to test for proper tracking of material. Pacer roller should be engaged at
this point.
The printing plate is affixed to the proper circumference print cylinder using .015 stickyback.
Making sure the corresponding correct gearing is used. It is then inserted into the top of the print station
making sure that the proper shaft, gear and print cylinder are utilized and the corresponding bearing blocks
in the right direction are used. You will find on the bearing blocks themselves, numbers from 61 to 91, (32
D.P.), 32 to 53 (1/8 C.P.) in one configuration and then reversing or turning the blocks upside down, you will
then be able to read from 91 to 122, (32 D.P.), 53 to 74 (1/8 C.P). This is necessary because of the large
range from 6" to 12" circumference that can be utilized on this particular press.
The bearing blocks are then put so that the T is to the inside of the machine, meaning that the
bearing blocks are T shaped and that the wider part of the bearing blocks are to be facing the center of the
unit itself. This will assure proper alignment of the gear, shaft, and print cylinder. At this point, consideration
should be given to the mounting of the printing plate on the print cylinder so that you do have some
adjustment horizontally on this shaft.
To accomplish this, there are two brass set screws in each print cylinder. Care must be taken that
this print cylinder is not torqued too tight so that the brass allen head set screw does not become rounded.
Brass is used so that scoring of the anvil shaft, scoring of the print cylinder shaft is eliminated. If steel set
screws are used, scoring of this shaft will occur which will cause difficulty in making the finer adjustments
that will be needed to center the print both horizontally and vertically with the cutting die.
The screws are added to the hold down for the bearing blocks and tightened. The two knobs now
can be tightened to bring the print cylinder and printing plate so that the printing plate just barely touches the
paper. Care must be taken to assure that the anvil shaft gear and the print cylinder shaft gear is meshed.
Next, insert the ink fountain being sure the fountain is tipped back to assure that the ink does not run out the
front of the ink fountain. Slide the fountain forward on the fountain rail assembly until it comes in contact with
the stops. Then lightly tighten the lock screw to hold the fountain in place.
In turning the unit on, a count must be on the counter in order for the unit to continue running. The
main on/off switch must be on, the toggle switch must be in run position, and the run jog button depressed to
initiate the running of the motor. The speed control can now be turned on and gradually brought to a higher
number so the unit will start revolving slowly. At this time, the ink fountain adjustment knob to the right of the
unit is to be turned slowly, advancing the ink fountain. (Care should be taken so that the ink fountain gear
and print cylinder gear mesh smoothly.) Continue advancing the ink fountain until the printing plate picks up
a slight even coating of ink completely covering the printing plate image, observing the print quality at this
time.
By depressing or relieving the adjustment screws, the ideal impression can be achieved. After the
impression has been set satisfactorily, insert the cutting die ( ) again checking the gear for the right 5
