Monson's Servo Auto Scanner

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.

Moderator: peterZ

User avatar
jck57
Posts: 376
Joined: 23 Nov 2009, 15:21

Re: Monson's Servo Auto Scanner

Post by jck57 »

rob wrote:
jck57 wrote:The last two or three pages are hard to pick. They want to all slide together. Not sure why.
Hmm. My guess is that there is a force exerted on the pages by the spine which tends to turn the pages. For paperbacks, the force is so great that the book closes if you don't hold it down. The fewer pages there are on one side, the greater that force is. You can probably see this effect just by setting a textbook down on a table, turning to the final pages, and seeing that the pages sort of stand up in the air -- if the book doesn't completely close on you.

I did this experiment, and observed how my fingers were arranged as they turned the page, and so the key here may be to use two fingers on the lower right. One finger (the "thumb") presses down on the page at the center of the bottom. The other finger (the middle finger, in my case) presses down on the page at the lower right corner, and then slides towards the thumb, lifting up as well. And while we're adding fingers, a third finger then slips under the page corner after it has been lifted, which enables turning the page.

--Rob
Thanks, Rob. Yeah, I noticed this problem on books with stiff paper. In order to keep the book from closing the flipper and the pusher are timed to pause close to the open pages to hold them back while the pressers extend. The book in the video has good paper so it doesn't really show this well.
User avatar
jck57
Posts: 376
Joined: 23 Nov 2009, 15:21

Re: Monson's Servo Auto Scanner

Post by jck57 »

snaguy wrote:He is referring to a feed roller. These are plentiful on eBay.

I recommend a small air compressor to blow into the spine before the page turning process.

When running a production laser printer and getting double sheet feeds we will fan the paper to prevent this problem. The paper tray has air blowing into the side of the paper to help separate the sheets and then elevate the paper onto the feed rollers which will push the sheet through the paper path.

With a bound book it is not as easy to fan the pages. Some books may have been squashed on the shelf.

And I must say very nice work.
Thanks. I'm experimenting with a feed roller by simply replacing the rubber tip with the roller. Even though it doesn't rotate, the roller makes a better paper pusher.
User avatar
jck57
Posts: 376
Joined: 23 Nov 2009, 15:21

Re: Monson's Servo Auto Scanner

Post by jck57 »

aeturneus wrote:Very excited about this method. I know that to help with separation of pages you can just get some air between the pages by flipping through them before putting them in a printer - would that help with this scanning method at all?

I like the idea of a feed roller, or two feed rollers, to separate the top page instead of a finger, but it seems to me the trick would be getting the weight right - too light and the feed roller won't move anything, and too heavy and the feed roller will grab more than one page. How would you set the weight of the arm that brings the feed roller down onto the page?
You're right about getting the down pressure correct. I've made some revisions to the pusher arm in order to better fine tune the spring tension.
aeturneus
Posts: 54
Joined: 23 Dec 2010, 13:57

Re: Monson's Servo Auto Scanner

Post by aeturneus »

Well, keep us updated as to your results and any problems you're having and maybe we can help.

I hardly need to say that once you have a relatively reliable solution, there will be huge demand for a kit. I'd like to build four or five of these for a project I've got in mind.
DDavid

Re: Monson's Servo Auto Scanner

Post by DDavid »

Could you post some guidance on the servo's? Like where you bought them
and/or the specs for what you found to work.
David
aeturneus
Posts: 54
Joined: 23 Dec 2010, 13:57

Re: Monson's Servo Auto Scanner

Post by aeturneus »

I'd like to take a crack at building one as well.
User avatar
jck57
Posts: 376
Joined: 23 Nov 2009, 15:21

Re: Monson's Servo Auto Scanner

Post by jck57 »

DDavid wrote:Could you post some guidance on the servo's? Like where you bought them
and/or the specs for what you found to work.
David
Sorry for lack of updates. Been doing lots of thinking but not much doing.

For reference; names I've given to the various servos:

Pusher. Lifts the corner of the page.
Flipper. Has the plastic tipped wire that turns the lifted page. Rides on the mechanism of Big Presser.
Big Presser. Presses on the crease of the book. It's big because the Flipper servo is attached.
Little Presser. Presses on the crease of the book.

Problems with the first version:

1. Pages tend to bulge when being pressed down
2. Cradle not rolling easily enough to re-center
3. Presser servos are stalling when down which causes overheating
4. Pressers not rising high enough to clear pages on some books
5. Need a tilting spine mechanism so the book vee stays optimum on thick books
6. Poor adjustment for the base of the pusher mechanism
7. Some difficulty in writing script for arduino

Some ideas to address these issues (not in particular order):

1. More powerful servos for the pressers.
2. Override springs for the servos so they always reach their target positions while the pressers are held down by spring pressure
3. New mechanism with parallel arms for the pressers so the pressers hit the book parallel to the pages and plumb.
4. Modified script that will have both pressers hit the book at the same time right before the cameras fire. This will double the downforce on the book thus hopefully helping to re-recenter the book. This should be easy to do except I'm having difficulty getting script to upload to my Arduino. Could be related to upgrading Windows after computer crash.
5. New cradle design that will roll side to side more easily, won't drag the spine, and will tilt the spine as it moves side to side.
6. Presser foot redesign so it's a more springy vee.
7. Bought a Pololu mini maestro servo controller. Tiny board built to handle up to 18 servos. External power supply for servos. Easier software interface. Haven't tried it yet.
8. Need shop assistant to make stuff, put away tools, clean up shop, fetch parts and sandwiches, listen to rants, offer encouragement and criticism.
aeturneus
Posts: 54
Joined: 23 Dec 2010, 13:57

Re: Monson's Servo Auto Scanner

Post by aeturneus »

The override spring idea seems like a good one. More flexibility in the mechanism should make it more reliable.

I also like the assistant idea - what part of the country are you in? Maybe there's a hackerspace around where you could get some local collaboration/assistance?
User avatar
jck57
Posts: 376
Joined: 23 Nov 2009, 15:21

Re: Monson's Servo Auto Scanner

Post by jck57 »

Servo shutter button presser. 1/4" Masonite base clears battery/sd card door. Servo saver (red thing on servo spline) limits force on camera button. Audio cassettes have just the right size screws for servo horn holes.
IMG_0238.jpg
IMG_0240.jpg
IMG_0241.jpg
IMG_0245.jpg
User avatar
Gerard
Posts: 154
Joined: 17 Oct 2010, 07:15
Number of books owned: 0
Location: Berlin (Germany)

Re: Monson's Servo Auto Scanner

Post by Gerard »

nice work, does the camera move under the pressure? i would think that a little support under the button/batterys is needed
how do you control the servos?

bye gerard
Post Reply