Print and scan the exact (exact!) same size.

[Semi79]

My workflow is as following: I draw on paper, scan the artwork and save it in Photoshop. Then I print a copy of the artwork and color it by hand (I don't like digital coloring). Then I scan the copy, which I have colored, again.  THEN I would very much like to have the lines of the original drawing in a Photoshop layer over the colored copy. (Yes, I remove the white and make it transparent so it's one layer with just crisp ink lines).Because I want to keep the sharpness of the lineart in the original drawing.

I have tried different settings all day but even if I print without margins or print as PDF without scaling I end up with a printed copy that is slightly smaller than the original. 

It seems to be scaled down unevenly.

It also seems to have rotated a bit.

It drawings need to be exactly the same size on the pixel, so that i don't get double lines anywhere.

In a last attempt I shrunk the original drawing so that it is well within the printing borders, imported it to Indesign, created a PDF and printed it in 100% scale. I then scanned it and it was much smaller than the (shrunken) file in Photoshop.

Can someone please give me simple instructions how to do this?

When I worked with my A4 Epson printer it was never an issue, but I need to scan bigger images, hence the HP 7740 purchase.

Or are your printers not supposed to be used by artists?

[Repairatrooper]

Are you scanning off the glass or using the automatic document feeder?

In my opinion you are asking for a level of precision that this level of product was never designed for. I curious if you had an Epson that worked is there a reason you changed brands because personally for this type of work Epson would be my choice.

[Semi79]

I'm using the  glass flatbed to scan. The reason I bought the HP was because it was the only A3 scanner/ A3 printer I could find, for home use. Another advantage with the HP flatbed is that it actually scans all the way to the border. With my old Epson I always had to try to remember not to draw all the way to all the borders of the paper, since at least one side would be slightly cut off when scanning.

I don't think it should be a high level of precision to be able to print/copy a document in the exact same size.

If I choose borderless printing the image is scaled up so it's still missing parts of the picture, only it goes all the way to the border.

But the borders are not the most important thing. If I could just print my picture in the same scale as the original, I would be happy, missing borders or not! I don't see why that should be too much to ask, it should be one of the main features of printing! To have control of the size of the actual print!