Building my DIY book scanner

Hungarian version of this article is available on djvu.hu

To explain this book scanner idea in a few words, compared to traditional flatbed scanners or special flatbed book scanners:

• 90 degree holder plate for the book
• no need to push the book
• no need to disassemble the book
• built from cheap leftover material
• scanning with a compact photo camera
• no wait for a flatbed scanner to move across a page slooooooooowly

There is an excellent community for building home made book scanners. By following the guides on diybookscanner.org it's easy to build your own scanner, that can scan a 300 pages book in 30 minutes. After 1.5 hours postprocessing work (in ScanTailor) you'll have very good black & white TIF images, that are straight, cleaned from noise, well readable. (No OCR or single-file conversion is included in this time frame.)

This is not a full guide, please read the "new standard scanner build" thread on the forum for understanding the basics of this design. After preparing your mind, you may find useful ideas in this article. I'll explain some of the barriers I faced and how to avoid them.

On the picture you can see how my bookscanner looks.

The bottom part is a V shaped "cradle" , that holds the book.  Above the book a V shaped glass (called "platen"), that I can lift up by using the drawer handle, when turning the pages. Using a button I take photos of each page (could use two cameras for faster scanning). From the top a lamp makes enough light. Everything else is black to avoid any reflections in the scan.

Lift, turn page, move down, press button, GOTO 1.

My father in law deserves credit for several ideas and help in making the hard work. Thank you!

Considerations in advance

CHDK - a custom firmware for Canon cameras

The original "New Standard Scanner"

Several users of the DIY Book Scanner forum mention the advantages of CHDK, a custom firmware for compact Canon cameras. If you are not sure whether you should buy a compatible camera, I recommend to do. I found CHDK very useful in the process, it extends the Canon camera with several features that are worth to try while scanning books.

• Remote control via simple USB cable + battery + switch
• Fixed object distance (manual focus, distance set in mm)
• Programmability (I made a zoom-set program, but ran into CHDK bugs, so not using it yet)
• Superfine JPG
• RAW image format (I'm not using it, superfine JPG brings the required quality)

Camera choice

I'm not sure about the camera requirements and it is very difficult to find recommendations in the forum, because everybody recommends his own model - without explaining what FEATURES are needed.

So far I found important:

• Manual exposure mode selection (using Aperture Priority mode)
• Custom White Balance, by taking a photo of a white paper
  
• Manual focus - and use CHDK's fixed subject distance override
• CHDK compatibility

I selected Canon SX150 IS - because there was one for good price on auction and matched all requirements.

Camera mounting screw

It's not easy to find the right screw. So I simply bought a cheap monopod camera stand ($14) and took the screw from it. Make sure to choose one that contains a removable screw. I can even put back the screw and use the monopod, so it's a win-win.

1. Building the base

In the New Standard Scanner the base is built from 4 pieces of wood. Instead that, I took a leftover from our kitchen desk, turned upside down for easier paining. This method does not need assembling like the original design and heavy enough to provide a good base. In this case the drawer slides must be "laid down", but they work perfect this way too. (There are some other scanners that use this method.)

This base is 575x460mm. 30mm thick, heavy.

On top of that, the base for the book holder is installed. This is similar to the Standard Scanner.

The moving part of the base is 435x460mm (15mm thick)

This part will move slightly, as you proceed from beginning of the book to the end. It is required to be movable in this concept.

2. Making the book holder

You need triangles that will form the V shape for holding the book. The New Standard Scanner uses one fixed and one moving side for this.

I used the same method for both left and right sides, this allows to do the same work on both sides. So both sides can be moved in this scanner. It is also easier to remove both sides for changes or painting.

The two rectangles screwed to the base are 160x110mm. The left-right moving triangles are cut from 115mm squares, thus: 170x115x115. (Thickness: 1")

On the threaded rot use a handy screw-nut, because you'll need to release and tighten that often. On backside of it use an closed-end-screw-nut that that locks itself when tighten.

On each side one piece of wood is mounted by 3 screws to the moving base, then the two triangles are connected with long threaded rod. Tightening the screws will fix the triangles in a position. After releasing them, the triangles can be adjusted left/right.

Not pictured here, but there are small screws in the bottom outer corner of the triangles - one in each triangle, that allows to fine adjust their angle by elevating the outer end. I find that useful to make the book holder match perfectly fit to the glasses. When everything is perfectly cut, and all material are brand new and straight, this may not be needed.

Two wood plates are screwed to the triangles, forming a 90 degree V shape, that will hold the book. This is the "cradle".

The plates that hold the book are 355x235mm, 10mm thick.

When you release the screw-nut, you can adjusting the "gap" to the thickness of the book. It may need adjustment at start, middle and end of average sized book.

3. Making the column

The column holds the platen - a V shaped glass that will press down the books, movable up and down - and the lamp.

The New Standard Scanner uses a two-part column, so that you can disassemble and fit in smaller place. My photos will show a single-part column, but on later photos you can see this was extended with a removable part to move the lights higher.

This bottom part of the column was made from 90x40mm wood, 675mm long. Later extended with a smaller 90x20mm, 410mm long piece to move the lamps higher. Overlap 55mm joined by 3 screws.

The column must be mounted to the base with two very strong screws, take 100mm or longer and very carefully mark their place.

The distance from the "V" part depends on how you mount the platen on the column, So before you drill these two holes, build the platen.

4. Making the platen

The platen is an up-down moving part, consisting of two glasses that you raise by hand when turning pages, and push down to the book to make the paper flat for the photo.

The New Standard Scanner recommends "gorilla glass", but I found plexiglass only, so I used that. The photo shows 5mm thick, but later I replaced it to 3mm, because that covers less from the inner edges of the book.

The plexiglass' surface gets scratched after a few books, so I recommend to buy replacements too.

Drill holes on the plexi, and then pre-drill via those holes on the wood.

Plexi are 3mm thick, 385x245mm. If you can glue them together, that makes the bottom much more stable. I have not tried yet.

The back wood is again a 30mm thick strong square 250x250mm (top corner cut to allow more movement). The front is a smaller and lighter wood, cut whatever you have that can hold the drawer handle.

The difference from New Standard Scanner here is the back side, where I used square, cut only the top corner of it, instead a triangle. This method leaves more space for mounting it to the drawer slides pretty well, without extra components.

Back side of the platen's mounting uses the original 'L' shaped accessories of the drawer slides, however not in their original position.

This type of drawer slide works very bad when mounted vertically. The balls of the drawer slides move down after 30-40 pages, blocking the movement and require a push up to top, so then it works for another 30-40 pages. Any replacement ideas are welcome!

5. Camera stands

Camera stands are little columns that hold the camera.

There are so many different solutions to this in the forum, that I was totally lost which one to choose and why. My father in law came to the rescue, inventing yet another solution. :-)

Aluminum bars, with holes in every 15mm. Start drilling around 350mm from the bottom and continue up to 100mm, I did to the top of it, later may use the holes.

The camera holder is a 20x20mm aluminum bar, 650mm long. Screwed to that a 200mm L shaped aluminum holds the camera. Sides of the L are 20 and 30mm.

The column is mounted by another small 'L' shaped piece of aluminum. The 'L' is screwed to the base by 3 small screws, to the bar by 2 (not visible), and the bar is screwed with a huge screw to the base wood. (Let the battery case not confuse you on this photo.)

Please ignore the little wood patch. It is included in the dimensions mentioned above. It was required because the lens of the camera was too near to the plexi in certain zoom levels.

The picture on the right should explain how this new camera mounting method works.

Holes on the vertical bar allow moving the camera up and down, based on size of the book. Small books are shot from lowest position, for bigger books the camera holder piece can be moved upwards.

Since the camera is on the smaller part of the 45 degree bar, the bigger (drilled) section may look unnecessary. But indeed it is very useful for adjusting the degree to 45 (using a simple 45 degree ruler on that side). Holes on the this part were drilled for flexibility, but wasn't needed so far.

6. Remote control swtich

You may think this is optional. Wrong. :-)

This is yet again different from the Standard Scanner. Most scanners mount the switch on the drawer handle. Maybe using my solution is not as fast, but I find this totally suitable. The switch is mounted into the base wood, so no weird methods are needed to mount a switch on a drawer handle and no cable is moving.

Runs with 3 1.2V batteries, USB cable, see CHDK manual for build instructions.

7. Counterweight

The counterweight is a little weight that helps lifting the platen. This is very useful, considering that you have to lift it so many times.

My solution is very similar to other scanner builds, uses a shiver, rope and weight. I've used an 1kg exercise weight wrapped in textile to avoid noise. All parts that are visible from the book should be black, so I needed a piece of black paper to cover the metal shiver.

The shiver is in a rectangle hole cut into the main column. It's not the best solution, you may find better ideas in the forum.

7. Paint everything black

For me, this was not obvious from the DIY Book Scanner forum.

Paint everything black.

Cover everything else with black paper.

Including the camera. I've used a box that I covered with black paper and cut holes for the controls. And used a black piece of paper on the top of the camera column, that puts the camera in shadow, as even the black-box had some effect on the pictures.

No light from windows may came in.

No other lamps can be turned on.

Happy scanning!

I plan to post follow-ups with more experiences and post-processing.