Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

New Standard Build Thread (mechanical trigger)

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.
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Gerard
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New Standard Build Thread (mechanical trigger)

Post by Gerard » 04 Jan 2011, 18:18

Hi, first i cover the mechanical trigger part

i could not wait to buy some cameras for my bookscanner in the hope that someday it will be chdk enabled, i don't know what was driving me to buy this cameras, building the mechanical trigger cost me a lot of time
first design was to clumsy and to heavy, and every triggering has coursed vibrations

this is the second design, maybe it can inspirer someone how has more expensive camera (but mostly they will have a remote trigger any way)

the work is done by a small servo, i hacked it (removed the electronics) an connect the motor to an switch

up till now this works, 5 books with out an missing image but i will definitely go for chdk enabled cams for my next scanner

one advantages is the usb port is free, i just need to connect it to the pc to download the images

have fun with it
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foam fixed with duct tape
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without the camera
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Gerard
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Camera Arm

Post by Gerard » 04 Jan 2011, 18:32

the camera arm able to move in every position, i would not recommend the design,
i bought the wooden balls at ebay, the problems with this arms they can not hold much weight with out losing slowly the position, they are hard to set (tighten the screws changes a little bit the position) and the build complexity is high (one half day to design and build two arms)
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Last edited by Gerard on 04 Jan 2011, 20:20, edited 1 time in total.

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Gerard
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Platen

Post by Gerard » 04 Jan 2011, 18:45

The Platen is made of glass, first i was afraid of breaking it, but bought glass sheets support each other and it works quite well, the sheets are between to wood pieces and glued with normal wood glue, the glass is form frame less picture frames (frame less frames ;) )

it can be easy cleaned and is the glass is thin and straight,


one tip: buy an extra sheets if you work with glass
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painted with black
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daniel_reetz
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Re: New Standard Build Thread (mechanical trigger)

Post by daniel_reetz » 04 Jan 2011, 20:38

Yeah! Lots of innovative design ideas here -- good even if it didn't work out right away. How does your cradle move left-to-right?

It really pleases me to see the huge black shroud over the scanner -- you will have excellent, glare free images with that kind of lighting control.

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daniel_reetz
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Re: New Standard Build Thread (mechanical trigger)

Post by daniel_reetz » 04 Jan 2011, 20:40

Gerard wrote: the work is done by a small servo, i hacked it (removed the electronics) an connect the motor to an switch
That's an awesome idea! Here I was wondering how you were controlling the little servo... maybe with Arduino or something, but a switch is a beautifully simple idea. And servos can be very cheap...
Gerard wrote: up till now this works, 5 books with out an missing image but i will definitely go for chdk enabled cams for my next scanner
Congrats! That's better than I did with my first scanner.

dtic
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Re: New Standard Build Thread (mechanical trigger)

Post by dtic » 09 Jan 2011, 13:37

Gerard, the servo in the photo pulls a string which lowers a piece of wood, causing a part made of foam and tape (?) to press the camera button. Did you first try using the servo to directly press the button? If so, what are the advantages the setup in your pictures?

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Gerard
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Re: New Standard Build Thread (mechanical trigger)

Post by Gerard » 09 Jan 2011, 14:44

Hi, sometimes i self don't know why

ok thats what i can see, i bought also a server controller, i don't know what i made wrong with the controller but he does not hold the position 100% and vibrating
so servor conroller had an problem, the other problem was it was controlled by a potentiometer, not that i am not able to make a switch witch output two resistor values
but hacking a servo seams easier

so the servo is now control buy voltage (on, off, polarity), so without an controller i just needed some stopping parts and i just had normal on off switches, to bring the servo return to the normal position i need a spring,

i think it is a combination of, what i currently had at the workplace,

i was not sure if the cams are ok, so i wonted an trigger which can trigger all kind of cams, but to put the server on an arm which is adjustable seam for me difficult,

i've diden't build this scaner not only for me, i just can see someone in the face and tell him you have to scan this book again because pages are missing, so my aim was to make something reliable, and to build a mount which is adjustable, stable and can handle the force (the idea to use foam for the trigger, to reduce force was developed later) and is small enough seams for me to difficult
if you use two cams it is more important to have a reliable trigger because you need full attention to hear if bought cams have shot the image

i could put the servo on a fixed mount and attach a thick wire, but i was afraid that the force will bend the wire in the time or while i am doing work on the cams

the first idea was also not to use servos, just cord and a food switch, but the camera arm was not stable enough,

so the this design is a chain of "goals to achieve", "what i had first in mind", "what was available in home",

so in short and my point: it's it is more reliable, the adjustment is not going to lose after work on the cams, to make it ready for a new cam you need only cutting a piece of foam and gluing it with duct tape on the right position

hope this helps to make you decision (buy chdk enabled cams ;))

dtic
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Re: New Standard Build Thread (mechanical trigger)

Post by dtic » 10 Jan 2011, 10:14

Thanks for the explanation. The foam part really makes sense when I think about it - it ought to emulate a finger better than a rigid servo plastic arm.

dtic
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Re: New Standard Build Thread (mechanical trigger)

Post by dtic » 14 Jan 2011, 19:34

I tried a bare bones servo trigger. It is pretty reliable so far. The metal strips I've secured the spring and camera mount to are bendable, which makes it easy to fine tune the camera button position.
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I have removed the electronics from the servo, just like in your setup, and use a battery for power and a switch.
The spring used above is of course overkill but was the only one at hand. The servo is so small that I bet a safety pin plus a rubber band would work as well. The servo only needs to be pulled back up a few milimeters.

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Re: New Standard Build Thread (mechanical trigger)

Post by jck57 » 16 Jan 2011, 11:48

Really like the possibities for firing cameras with servos. From a cursory net-scan they appear to be lighter weight and cheaper than solenoids and air cylinders. I'd rather do servos than mess with software and usb triggers. What's the downside?

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