New Standard Build with Lego Cradle

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duerig
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New Standard Build with Lego Cradle

Post by duerig »

I've been working off of the New Standard Build tutorial. I have a hand drill, no saw, and little experience. After having the hardware store cut my 2x4's for me, I began with a standard base and columns:

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The cradle in the build required a saw for the triangular pieces which I didn't have. So I built the cradle out of Lego instead. Here is a partially completed build with one camera and two acrylic plates loose to approximate a platen:

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The completed (for now) build with a very simple platen consisting of two acrylic plates glued along their edge:

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Here is a close-up of the lego cradle. To adjust the gutter for the spine, you can pop the outside pins and move one side. Right now it can only be locked in 8mm increments by attaching the pins through holes:

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Here are a couple of sample scans with no cleanup or other post-processing (I still need to figure that out):

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In both cases, they seem more readable scanned than the original did. So I think this is a big win. My first project will be to scan and then throw away all those little manuals and pamphlets that I have lying around the house and fear I might need some day. Then I might try scanning a full length book.

The biggest defect is the fragility of my minimal platen. I've already broken one acrylic plate trying to drill it. But the glue I am using now is definitely not sturdy at all. Any tips about how to make a robust platen that is still simpler than the new standard one would be great. What I like about the current platen is that it is light enough that I don't feel like I have to tackle the complicated business of mounting it on the drawer slides.

It is also not clear to me why the extra complication of mounting the drawer slides on the side of the column is required. It seems like it would be a simpler job to mount it on a single drawer slide on the front of the column. I am probably missing something.

Let me know if you have any tips or comments about where to go next to improve this build.
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daniel_reetz
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Re: New Standard Build with Lego Cradle

Post by daniel_reetz »

Thank you for sharing your work! Try changing your white balance to "tungsten" or the light bulb icon, your scans should become white instead of orange...
duerig
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Re: New Standard Build with Lego Cradle

Post by duerig »

Thanks! I'll try changing the white balance setting. I was afraid that I'd have to color-correct in post-processing.
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Mohib
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Re: New Standard Build with Lego Cradle

Post by Mohib »

I must say the lego assembly is very cleanly designed! And as someone who has just fractionally more tools than you (a hand saw being the main one! :) ) I can understand where you're coming from!

From the pictures it looks like you are using two cameras as I can just see the second in one of the pictures. If you are using two, or need to use two, how are you triggering the cameras simultaneously? Are you using a remote of some kind?

Also I think you'll need to figure a way to move the platen efficiently, and without being concerned about it breaking or falling apart -- as you seem to be from your comments -- or your throughput is going to be reduced quite drastically. Could you provide a sketch of what you were thinking for the single support slide mechanism you mentioned?

One other observation, it looks like your cameras are off to the side of the platen (i.e. close to the lamp support on one side and the opposite on the other side) i.e. near the top and bottom of the book and not centred across the width of the platen (i.e. across the spine of the book), and so the one camera visible in the pictures looks like it's been tilted a bit to point at the centre of the page. This will cause some key-stoning (i.e. the pages will appear wider at one edge and narrower at the far edge, giving them a perspective look) which, if it's a problem for you, can largely be reduced if you move the camera support to the middle of the piece of wood it's attached to and making sure it points squarely at the page's plane.
duerig
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Re: New Standard Build with Lego Cradle

Post by duerig »

I am using two cameras. One of the deficiencies of my setup is that they are not the same camera or even the same resolution camera. So my scans for facing pages will be subtly difference, with one side in 12 MP resolution and the other side in 10 MP resolution. Right now I'm manually pressing the button on both cameras as well. At some point, I may upgrade to two Canon Powershot cameras which are recommended elsewhere and trigger them both via my PC or a remote.

The platen is sturdier than I had feared, but it is still quite cumbersome. So that is another obvious upgrade to make as well.

I haven't thought through the single-slider idea too much. But if the platen is light enough, it seems that a single slider sandwiched between the post and the platen might be better:

POSTPOSTPOSTPOST
slider
PLATENPLATENPLATEN

I've also now taken your suggestion about centering the cameras properly to prevent key-stoning. I bought two straight brackets at the hardware store and bolted them to my angle-brackets. This has extended the mount enough to get both cameras into the approximate center.

One other problem I've noticed is that the lego cradle floats in the middle without being properly attached to the base. That makes it easy to pull out and adjust, but it also means that it is easy to move it slightly when I turn the page. I'll have to think about how to fix that.

Thanks very much for the feedback so far. As I use the scanner more, I will keep thinking about how to tweak it.
duerig
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Re: New Standard Build with Lego Cradle

Post by duerig »

One of my two cameras didn't work (could not focus on the page properly and would not recharge). So I bit the bullet and bought two refurbished A2200 cameras with AC packs. At the same time, I got two gooseneck mounts and installed CHDK/Spreads so that I could control everything from my laptop. With these improvements, I've managed to get a top speed of 1400 pages per hour.

The platen is still not mounted. I have added axles to the corners of the cradle with small pulleys to keep them in place. That allows me to ensure that the cradle remains at a constant angle with regard to the base. Lifting the platen to flip pages is fairly straightforward, but since it is not mounted to anything, it is easy for it to shift left and right a bit while scanning. I now understand the purpose of the sliding drawer underneath the cradle in the normal build. That, combined with a mounted platen allows you to maintain a very consistent page position. And this is especially important with paperbacks that easily slip and move within the cradle as the spine tilts one way or another.

On the last book I scanned, I was down to 600 pages per hour because I had to crane around and double check each camera viewer to make sure that things were still in frame every few pages, especially at the beginning and ends of the book.

Image

For the future, I will hook up a couple of small 4.3" TFT screens to the cameras facing me so that it is easier to ensure accuracy as I scan. I'm also looking into lasers for dewarping. I also wonder if a vertical laser line straight down from the column could act both as a guide and as an easy way to auto-crop the facing page because Scantailor isn't always that smart about it.

With laser-based dewarping, it might be possible to go platen-free. The cradle and dual cameras could keep warping to a minimum while an extra laser-callibration photo every ten shots could remove the remaining warp.
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