A 12-page document would print on 3 sheets of paper, so inside bleed (at the spine) is probably not going to be an issue, so you can set it to 0, or leave it the same as the bleed on the outside edges and let the imposition software at the printer ignore it (presuming you are letting the printer do his job of imposing). Sending a 12-page PDF (with bleeds) in consecutive order would be the normal delivery.
But always, when you have a question like this, you should call and ask the printer what they want.
Thank you Peter,
Just to clarify, when you say "a 12-page PDF(with bleeds) in consecutive order", you mean single pages(not spreads) in the way you created the file (e.g. pg 1,2,3,4...) because the printer can print as a booklet from that?
But what I'm confused here is when I prepare the file like that and preview the booklet print, there is a big white border between the blue and the orange pages (see attached). How do I prepare a file so it doesn't have that gap in between?
Imposing is not your task, the printer has to do it. Send to the printer single pages with bleed according his specification. Don't use the booklet function as it is not so good in InDesign.
If you want to make a dummy, make a different PDF file and export it without bleed in the inside, but be aware, most printer don't print registered pages in back and front, so you can use it only as dummy.
If you feel the need to do an in-house on your Canon printer you'll need to set the inside bleed to 0 and leave off the marks in the export dialog when you make the PDF. Your Canon device is not as sophisticated as your commercial printer's software and equipment.
Thank you Willi and Peter!
I see, so sending the printer single pages with bleed, even I have bleed cover is enough. Whew. No, I do not need to print this in-house, I was just freaking out because the preview did not seem right. Last time I had to do this, I sent in the wrong file to the printer (sent the spreads instead of single pages) and the printer did not even bother to contact me and went ahead with the job and the page numbers all got jumbled up and I got into a huge trouble so I wanted to really make sure what the normal procedure is to send in for a spreads print.
Thank you guys!
Most likely, they'll take a PDF, exported from InDesign in some variety of PDF/X (4 is the latest and most versatile), in single pages in reader order, with bleed an all edges but the inside, use their own software to organise the pages into the right order and position on oversized sheets, and add their own printer's marks.
But what really matters is, what does the printer ask for?
Thank you Danny! I wish I had talked to the printer directly but somebody else is handling the printing and although I've asked that person to ask what the printer prefers, they just went ahead with whatever files I sent in and already came back with a proof.