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pmkprog · #1 (**permalink**) 08-10-2005, 06:24 AM

We have a Lotem 800 and our plates are measuring correctly for gripper when we plot sheetwise plates. When we plot perfecting forms, they are not backing up. They are .25" off.
None of the parameters that we know of have been changed. Any ideas?

David · #2 (**permalink**) 08-10-2005, 06:35 AM

Quote:

Originally Posted by pmkprog

We have a Lotem 800 and our plates are measuring correctly for gripper when we plot sheetwise plates. When we plot perfecting forms, they are not backing up. They are .25" off.
None of the parameters that we know of have been changed. Any ideas?

Your imposition must be out of sheet center by 1/8". Perfecting forms need to have the tail and gripper margins the same, so when the sheet is flipped edge to tail it will back up.

Hope this helps,
David

pmkprog · #3 (**permalink**) 08-10-2005, 06:40 AM

The layouts are centered. That's why we are puzzled.

David · #4 (**permalink**) 08-10-2005, 08:18 AM

Quote:

Originally Posted by pmkprog

The layouts are centered. That's why we are puzzled.

Have you tried to force it to move the .125"?
Does it still come out wrong?

The reason I ask is I've seen some before that when measured it appears to be off a specific amount, you move it that amount (usually half the amount for back up purposes), and it's still off by about half the amount you moved it. Kinda weird, ended up trying about three times and finally got it in.

Hope this helps,
David

PS. How are you determining the file is off? Is it on press where you noticed the back-up problem?
How is the press set? Are the cylinders set at zero or have they been rolled any?

pmkprog · #5 (**permalink**) 08-10-2005, 08:28 AM

The pressmen complained that the plates didn't back up. They zero'd out the cylindars before they started the run. We actually got the layout from another shop. It appears that they don't add the center mark, or set the center mark depth to zero. We usually have it set to .125". Once that got added, it looks to be fine. It should n't make a difference should it?

David · #6 (**permalink**) 08-10-2005, 08:47 AM

Quote:

Originally Posted by pmkprog

The pressmen complained that the plates didn't back up. They zero'd out the cylindars before they started the run. We actually got the layout from another shop. It appears that they don't add the center mark, or set the center mark depth to zero. We usually have it set to .125". Once that got added, it looks to be fine. It shouldn't make a difference should it?

Hmmmm.....You wouldn't think that it would, but, I guess in this case, it does.

Glad you got it figured out.

David