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View Full Version : Creep calculation for 2 up work


sequoyah
06-18-2006, 07:20 PM
What needs to be done in order to achieve the correct creep calculation in the case of 2 16 page signatures printed sheetwise on the same press sheet for a smyth sewn book? These are side gathered signatures, so the binding style is perfect bound. But since the two signatures on each press sheet are independent, that is, side gathered and not nested into one another, how will Preps know to treat each separately?

This must be a common practice in the book industry. I have searched the Knowledge Base, but found nothing for 2 up work.

Al Ferrari

jcprep
06-23-2006, 10:11 PM
Al,
sorry if i'm missing something, but I thought only saddle stitched jobs needed to worry about creep. We don't do any shingling on any of our perfect bound work. I've only been at this a few years so I could be wrong, but I know thats our thinking here.
Nate Lightner

sequoyah
06-24-2006, 03:32 AM
Thanks for the response Nate. After not getting any answers here for a few days, I posted the same question at prepressforums.com and got quicker responses, but the focus was the same as yours: "why bother to apply creep in perfect binding jobs?" And no solutions were offered.

Well suppose these signatures are of a small page size, and printed on a large press sheet, so that we are dealing with 32 or even 64 page signatures. And note that my original post is about Smyth Sewn signatures for a Case Bound book. Perfect bound in this case is only the applicable Preps imposition, but the product is of a quality level that merits the application of creep. Now, the procedure is straight forward if the job were printed on smaller sheets, one signature per sheet. But both the run length and the available press equipment dictate the use of the larger sheet size accommodating 2 signatures. As stated earlier, this must be common in the book industry.

The one work around that comes to mind is a two step process of first outputting to postscript file the imposed single signatures with creep applied, and using a sheet size half the size (or less) of the eventual 2 up press sheet. Distilled pdfs of these are then imposed 2 up in a second step without creep. The pdf step is needed because Preps will not accept as input, its own postscript output. Yes this is a bit convoluted, which is why I was looking for a one step method.

Al Ferrari

jcannon
06-24-2006, 07:31 PM
Sequoyah,

Maybe I'm missing something here but couldn't you just build your template 2 up the way you want your pages to appear on the press sheet? Then you will have each page number on the template twice but you only have to place them in the file and run list once. We use this method a lot on our large web presses although we don't apply creep. The benefit for us is half the run time to achieve the desired quantity with it being ran 2 up.

Also if you make your template up as "perfect bound" you might get surprised at how Preps applies creep. We made the mistake once of making our templates "flat work" instead of "Saddle stitch" and we got some weird results. I would make the template "saddle stitch" type and then number your pages manually for perfect bound. Should work I think.

Joe

sequoyah
06-25-2006, 04:25 PM
Joe,

Your method does cut the number of impressions in half, still requires as many plates and makereadies as there are signatures. But your response makes me realize that I neglected to explain that I am trying to put two different signatures on the press sheet, not two of the same signature. And as I think about it now, I realize that would require two separate impositions on the press sheet which I don't think Preps can do. Using independent pages is ruled out because the creep calculation and adjustment works only on imposed pages. So I think the two step work around I posted earlier is the only way.

Anyone else have ideas about this?

Al Ferrari

jcannon
06-25-2006, 07:33 PM
Al,

I think your best bet then would be to go into your template and set the creep on the individual pages. For instance you could select pages 13 and 16 (preps will automatically apply the creep to the back side pages) and set the creep to say 1/16". Then select 9 and 12 and set it to 1/32" and then just set them all to the values you need. You would only have to set this up once in the template and then don't apply any creep in the job. We use this for the bottling function for 64 page perfect bound sections.

Joe

sequoyah
06-25-2006, 11:27 PM
Joe,

I had not thought of doing it "manually" since Preps is suposed to do this automatically. I'll check that out. Thank you very much for the suggestion.

Al Ferrari

jcannon
06-27-2006, 06:27 PM
Al,

Your welcome. Preps does do creep the traditional way. I've used it and it does work. I hope my suggestion works for you. Good luck.

Joe

sequoyah
06-28-2006, 05:03 AM
Hi Joe,

I am confident that using your suggestion will I will be able to do what I want. In fact I just finished making a post on prepressforums.com about using the technique:

http://www.prepressforums.com/ftopicp-50470.html#50470

By the way, my two different signatures on the press sheet will each have signature collating marks that I have customised from the ones supplied with Preps. These will step down the spine in the standard way, but will print sig number series that use 2X-1 and 2X math. Let me know if this is of interest to you.

Al Ferrari

steveburns
09-01-2006, 04:54 PM
Hi Al

Sounds like you do some technically challenging work. Unfortunately you are correct. Preps cannot gang different impositions together on your press sheet. We have run into this scenario a few times. With the only solution was to use independent pages and manually apply creep. I hope preps evolves to gain this feature soon. Kodak are you listening?

Steve