how to test a SM74 used press

Hi,
I am willing to buy a used SM74 2 color machine and I would like to know if somebody can tell me what to look at and what tests to do when buying used machines.
Thx

 

Run a solid on each unit. One at a time and if you see lines across the solids about the size of the cylinder gears than you have worn gears. Run screeens on both units. Checks to see if you have tails or dots are not round. Again bad gears. Run a duotone on both units. Check to see if dots register correctly in the half tones. If not, bad grippers, release cams, or again gears. Also run a solid on the plate to blanket to back cylinder to look for low spots.

 

Lift a few grippers on the first unit on the impression cilinder and look if the poly-urethaan-pad is still there. The first signs of wearing out are on the corners, there the plasic starts tot dissapear and the shiny metal will become visibile. You'll need a little mirror.

 

to test the integrity of cylinders i like to do as follows...
1 make sure both plate and blanket cylinders are packed to man. specs
2 make sure roller stripes to plate are correct
3 make sure blankets are either new or at the very least not hammered
4 pull break away solids on a gloss coated sheet
you want to back off back cylinder pressure unitl you see the solid image start to break up. once it starts to break up you look for an even breaking up along the entire sheet. low spots on any of the cylinders will be evident at this point. be sure to use the maximum sheet size for the press your testing
hope this helps,
tom