sm 52 4 color gripper bar adjustment

[52 valley view]

Lead edge of sht. on the drive side is nicking every other sht. on a 14x20 sht. of paper #70 offset txt.

Does not do it on a 12.5x19 Is there an adjustment and where. Tried putting a new pad on that end gripper but no luck. Is something else causing this

press is a 1999 model thanks

 

[contractor]

Find out exactly which gripper it is sounds like the double transfer. That gripper may need to be adjusted to correct timing and pretension also set.
Timings are different on each cylinder.

 

[mgk_print]

If you don't use those outer grippers enough, you'll have to shoot some wd40 or similar on them and work back and forth. Make sure to blow out with air hose after.

 

[spikeboy]

every other sheet sounds like transfer like contractor suggested

 

[aqazi81]

Apply a very small amount of any ink on a gripper pad of 1 gripper bar at each double diameter cylinder and run few sheets to find out exactly which bar is problematic.

 

[exheidmech]

Is this machine low pile or high pile? have you tried going to minimum gripper bit to see if this helps your issue?

 

[52 valley view]

Have narrowed it down to a gripper bar at the delivery end of press that is causing it

 

[52 valley view]

Is there a adjustment on those bars at the delivery end? If so where? Thanks

 

[junker1984]

3mm set, bottom rear

 

[alibryan]

If it's a low pile delivery and it's happening to every other sheet consistently, it can't be the delivery gripper bars - because there are three of them.

Try running some paper through the press and with the press full of paper from feeder to delivery, stop the press suddenly, either by E-stop or by raising a guard. Then lift the doors individually between each unit and look for when the first sign of paper nicking occurs. You should be able to inch the press to the exact spot where it's happening and then make the necessary repair from there.

 

[exheidmech]

Is there a adjustment on those bars at the delivery end? If so where? Thanks

There is no adjustment for SM52 gripper bars in the machine. Grippers have to be set either at transfer point which isn't easy or there is a jig to set them outside the press. But, as already noted there are actually 3 gripper bars in the delivery on SM52 so the every other sheet theory is not going to work in the delivery. Also, the 3mm set screw on the bottom of the gripper bar is not an adjustment for the grippers. This set screw is actually a mechanical stop for the gripper bar. Since the cam follower is only on a cam for a short time there needs to be a resting spot for the spring load of the bar. This set screw serves as the resting stop for the gripper bar, in other words don't screw with it. Have you tried minimum gripper bite?

 

[junker1984]

Interesting. Not sure what to say to that, but if he's having trouble with one gripper, and it's pivoting freely, I would suggest turning set screw on the back side of the affected gripper a bit clockwise. Gripper may be bent, in which case it may take a bit more thought.

 

[exheidmech]

Interesting. Not sure what to say to that, but if he's having trouble with one gripper, and it's pivoting freely, I would suggest turning set screw on the back side of the affected gripper a bit clockwise. Gripper may be bent, in which case it may take a bit more thought.

Were you refering to the set screw that is on each gripper or the one thats on the bottom of the gripper bar? The one not to mess with is the single set screw on the bottom of the bar itself, this is the mechanical stop. Each gripper has a adjusting screw for adjusting the gripper, this one is fine to move. Sorry if there was a misunderstanding in your post.

 

[junker1984]

Yes, exheid. My post referenced back side of each gripper...not the one on the bar. Valid point though.

 

[PKT FDO]

Dear, check delivery chain tightening & transfer timing (if needed adjust opening cam)