DIY High-Speed Book Scanner from Trash and Cheap Cameras

Step 13 Bookholder: Introduction and Design Issues

Congratulations on making the base for your book scanner.

One of the nastier problems in scanning books is that the "center" of the book shifts as you flip through the pages. I have a couple pictures with a very thick book that demonstrate this problem. Essentially, with books that have any thickness, the center "V" shape of the book moves left to right as you flip pages. However, the platen of our book scanner does not move. That means that we need whatever is holding the book to slide freely, to center it below the platen.

This is the main reason why the base of the book scanner must have a smooth surface, like melamine, plastic, or counter top. Things have to slide.

Comments

[spamsickle]

I pulled the drawer supports out of a really nice desk someone had tossed -- sliders on ball bearings, with 3 metal extensions -- and was planning to use two of them for base sliders and one on the column to support the platen, so that the base would move smoothly from side to side, and the platen would rise smoothly straight up and down (no hinge). I may still do that, on my own version 2 book scanner, but for now I'm not sliding anything and I'm not attaching the platen to a center column. I'm just letting my book rest in a static base, and setting the platen on top of it. The problem is not just that the center of the book moves as you page through it. If you're working with a 3-inch book, on page 1 the left side of the book is three inches higher in the VST (cradle) and three inches further away from the camera than the left side will be on the last page of the book. And obviously, the right side is three inches closer and three inches lower on page 1 than it will be on the last page. Ideally, you want the camera on each side to get the same view of a page from the first page to the last. While "centering" the book in the platen helps some, it seems to me that the only way to insure a consistent view is to adopt the design that it looks to me like the bkrpr people have chosen, and have the cameras attached to the platen itself. In that configuration, the images seen by each camera should always be the same distance from the camera, and appear in the same position in the viewfinder, from the first page to the last. I went with 1/16 inch acrylic for the critical (page-pressing) planes of my platen, and while that seems to work fine with the absolute bare-bones implementation I'm working with now (no center column, no handle, just lay the platen in the book and shoot), there's no way 1/16 inch plastic is going to support a couple of cameras. So I'm thinking for version 2, I'll build a frame to hold the platen plastic, which will also be capable of holding cameras. In that design, the sliding cradle and a counter-weighted vertical-rise platen will make sense.

[autophile]

It looks like you have thick acrylic endwalls. Maybe use those to support a piece of wood to which the cameras get attached? I see your point about the inconsistent image sizes...

[spamsickle]

Yes, the endwalls are 1/4 inch, which I've had sitting around for years. Actually, now that I've started scanning, I'm inclined to think the inconsistent image sizes isn't going to be a significant issue for me. I'm using bright lights, which allow me to use a large f-stop, which gives me a lot more depth of field than I need. If I just frame the page with a bit of space all around, I can shoot straight through and get whole, in-focus pages from front to back. While the page may not appear exactly the same size, or in exactly the same position each time, that's not going to affect my ability to read them, and for me that's really the whole point. I've also discovered that the "static electricity" effect allows me to turn the page when I lift the platen, if I just give it a twitch to the left, so I think this design may be where I stop. If I try to get fancy with platen-centering rollers and counter-weighted columns, it won't be easy to lift the platen and turn the page with a single move. If I can figure out how to upload a video to show how it works, I'll show you. Much thanks to you and Daniel and bkrpr. This came at precisely the right time for me. I'd been using a flatbed scanner, which started adding yellow streaks to the scans. I googled "book scanner", saw the commercial products selling for $5000 to $30,000, and then saw this one. It's fifty times faster than the flatbed, and no yellow streaks.

[spamsickle]

One more "practical" observation. About 200 pages into that 3-inch book, I started running into the same problem I'd had with flatbed scanners -- the book's pages "bow up" toward the spine, distorting the image. Let's face it, a 3-inch book is just not made to fit neatly into a V-shaped thing, except when you're near the front or the back of the book. I saw in one of the multi-thousand-dollar commercial solutions that they turned a dial, and the V-shaped cradle opened out and a little platform rose in the middle to support the thick book's 3-inch spine. That's way too fancy for me. I'm not making commercial scans, and I'm not making a commercial scanner. I tossed a 1 inch diameter PVC pipe into the center of the cradle, and that took care of the problem. The spine of the book actually "rolls" across the pipe as it's paged from front to back, and puts the open face of the book in a more natural v-shape to receive the platen. I'd bought the PVC pipe to implement that light-supporting solution that you1 used, but I discovered (in my case) that the clamps on the halogen lights just wanted to slide around the circular pipe rather than support the (heavy) halogen lamps in any position that would enable me to direct the light straight down. Now, I'm clamping the lights to the side of a couple of the drawers I salvaged from that desk, and supporting the drawers on an ironing board. BTW, someone had mentioned wanting a portable version, and (except for the platen itself) mine pretty much qualifies. Nothing is bolted, clamped, or glued together. The supports for the VST (cradle) are just a couple of sawed boards sitting on any horizontal surface. The VST itself is just two more boards (shelves, in this case), laid inside the support. It all goes together or comes apart in 15 seconds. The cameras are on tripods sitting on each side, and I'm triggering them manually (as bkrpr did) after resting the platen on the book.

[dark_slasher91]

wow this is what I'm looking for. It is portable and has a very small footprint that will fit in any dorm room or cramped studios.

[daniel_reetz]

I never mentioned it in the instructable (just forgot) but I actually have a little stack of shims -- a paint stirring stick, a bar of aluminum, and other stuff -- which support the binding of the book in much the same way. the pipe is a cool solution.