Sunday, August 20, 2017

Book Scanner v2.0

Since y'all thought I did nothing for two months, I'm going to post a little more. That old, wooden-framed book scanner had some issues with it.

  1. It was heavy, and awkward to move around
  2. It didn't set up square (which is really kind of essential).

So, what to do? Start over.  Here's what I needed designed into it this time :

  • Compressability - I would like something that can be dismantled into something small (the wooden one 
  • Lightweight - It needs to be very portable, and not a chore to lug into a court house to convert old records into PDF
  • Squareness - You want the pictures to be oriented properly
  • Repeatability - getting it set up over and over, I want it to be fairly consistent and easy to use

I needed portability, and that demanded that things were done in lightweight plastics.  No heavy woods.  The requirements for squareness meant I had to grab the platten bases and put a hinge on them - if they were square, the frame would likely be square.  Also, the supporting frame under the platten had to be square, and solid - no taking this one apart.  That means it had to be small.  A few quick notes, and then it was off to Dome Hepot for PVC pipe and Ded, Dath, and Deyond for some plastic cutting boards.  The sizes of the cutting boards will depend on how large you want it to be.

Now, with my parts lined up, I could start assembling it.  The two 90*x90*x90* three-way elbows were for the lower frame front.  I used two extra tees not shown in the above picture, with threads to match those 90* three-way elbows.  The bottom frame was approximately as long as one cutting board was wide.  The length between pillars was two-thirds of the length of a cutting board,  The bottom frame assembled as :

If you look closely, you will note I used a compound miter saw to cut those elbows at the same angle I wanted my platten base to be.  Those black things will thread out, but the rest of the frame was glued together to keep it solid and square.

Once I had that in place, it was time to do the platten base.  This was done using two cutting boards and a piano hinge.  First, it was time to mark out the holes in the cutting board for attaching the hinge.  Since the piano hinge has even holes, I could do them all at once.  I taped the boards together, drilled them out, then counter sunk the screw heads.

I did have to use the belt sander to put a bevel on one end of the cutting boards, just because I needed them to open up to the specific angle (a full 105 degrees).  I used the smaller cutting board from one of those to add a hinged support.

Once the platten base was complete, I could turn my focus to the upper frame and pivot. The Frame was put together using four elbows and two tees, along with some pipe.  For the pivot, you can use anything.  I had some spare hiem joints from working on the corvette headlight conversion to electric,  and so I opted to use those.  The pipes DO need to be there - they fit into the lower frame's tees on the back - , and that helps the upper frame keep square.

It will work with cameras on the upper frame, and the actual glass platten will hang from that upper frame.  Lift up, turn the page, lower, snap pictures, and repeat.

Once I get the physical complete, I will start to do the digital.  The digital base will be a raspberry pi running Linux, two Canon SD cameras, and CHDK firmware allowing control over the cameras from inside of Linux.  The raspberry pi will have a switch on it to trigger the photo, and it will also use an SD card to store the pictures.  I have a number of books to convert as a test.

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