Ryan's Stowable Scanner

Ryan's Stowable Scanner - 01

Builder: Ryan_phx
Forum Post: Ryan's Stowable Scanner Build Thread
Material: 1/2" Baltic Birch plywood, 4 brass rollers
Platen Angle: 90°
Camera Setup: dual
Camera Models: Canon A480

by Ryan_phx
Location: Phoenix, AZ

Overview and Goal

The idea is to make a scanner that is stowable—not portable, not collapsible, but stowable. The base will double as the storage case, and everything will be able to disassemble and fit inside the base, which should be able to fit under the bed or the desk, or get stashed in the closet. I should be able to assemble/disassemble it in just a few minutes, with no tools needed.

Material List

With the exception of the cameras and a few pieces of hardware, it will be built entirely from what I have on hand, mostly 1/2" Baltic Birch plywood. I've got 4 brass rollers designed for sliding doors. One 3/4" piece of BB ply, a few bolts and wing nuts, a drawer slide, and a couple of spacers. The USB trigger.

Questions and answers

QR: If I use LEDs, does the mounting height change?

AD: The exact distance of the lights above the platen is something that's easy to figure out after you've built the base - just lift up the floods until they don't appear in the camera image anymore.

The distance is a combination of four factors:

*The angle of the cameras to each platen face (ideally they are normal to each platen face).

*The distance of the cameras to the platen face.

*The size of each platen face.

*The total area presented by the lighting surface (so a large light VS a tiny LED will provide a larger glare image).

As for LED lighting, I just received two BuckPuck's I'll have a wiring diagram and how-to instruction's.
LED lighting is pretty sweet, though it's not as cheap and powerful as halogen. You can always start with the halogens and then move to LED later.

QR: Are you using batteries for your LED's

AD: I am using a 15V AC adapter for my 4 [[LED lighting|Cree Q5]]s. If you went to 3 Cree Q5s, you could get down to a 12V adapter, which is free in the junkpile or $1.89 on eBay. Might pay to look around the junkbox though as the supplies that come with laptops and the like are usually a bit more sturdy.


Base and Cradle

I got the movable base and cradle built today, and the platen has been done for about a week, so I thought I'd post a few pics. Next step is finishing the main base/case and adding the platen lift/lightstand.

The cradle supports are mortised into the cradle rest and the base—they'll stay in place, but can easily be lifted out of the mortises to be stowed. The glass is attached with double-sided outdoor mounting tape. I've used this stuff before on other projects, and it's very strong. When flattened out for stowage, the cradle and platen are less than 3.5" thick.


When the platen lift/light stand and camera supports are added it will still fit under the bed. The case itself, which I started on today, will measure about 17x25x6.5".

The next step, is to get the rollers attached to the case. In another thread, Daniel used rollers on two threaded rods that spanned the base to allow the cradle to move side-to-side. I'm doing something similar, but without the rods. I've got 4 brass rollers designed for sliding doors, and I'm going to attach them directly to the inside of the case with bolts and washers. They'll spin freely, and there won't be any rods taking up space in the case. I think in Daniel's design, the rods actually helped stabilize the base, but I don't need that reinforcement, so no rods for me.


Then I'll build the platen lift and lightstand. That'll be easy—one 3/4" piece of BB ply, a few bolts and wing nuts, a drawer slide, and a couple spacers. Once that's done, the camera supports (I have a clever idea for this, but you'll have to wait to see!) will be next. Then, hopefully, the LED light system.

Okay, I finally got some pictures of the scanner. The USB trigger isn't shown, and my LEDs still haven't arrived, so the light rig isn't shown, either, but everything else is done. The only problem is that the cheap drawer slides on the platen aren't very good—I'm probably going to replace them with better ones.



Here it is, completely assembled:

With the platen raised:

In that last shot, you can also see the locking bolt on the right—that's the side that slides out to accommodate larger books.


The total dimensions of the stowed unit are 17.5" x 25" x 6.5". It fits under the bed!


The trigger isn't working right. I used this design, and everything is wired correctly. When I press the button, the cameras will focus, but I can't get them to actually take a picture. Well, one of them did once, but I can't replicate that. I've been pressing the button in different ways, on the theory that a press-and-short-delay-before-next-press might be interpreted by the camera differently than two rapid presses, but that doesn't seem to work, either. When I press the button, the screen goes black, and when it comes back, it simply shows the "live shot" with the "Auto" box in the middle, that retreats to the upper right corner. I'm running the latest CHDK build on both cameras, so I'm at a loss here. The only thing that might be an issue is the hub. I've always been a bit skeptical of the quality of this hub, so I might just grab a USB splitter this afternoon and see if that works better.

Questions and answers

QR: One other thing-the camera makes several little clicks when I press the trigger—is this normal?
(I've noticed that if the camera has nothing to focus on, the camera may not trigger as expected)
When I was using it, it was mounted on the scanner with a book in the cradle, so it had a target.

AD: I'm guessing that the hub is your issue. You should be able to test it by connecting a USB cable to the USB port of your computer, and then plugging that into the camera. If the camera fires, it's a problem with the hub. If the camera doesn't fire, or does the same thing it's currently doing, then the problem is probably not the hub.

QD: What happens if you press the button twice? Does once "arm" the camera, and twice "fire" it?

AR: The first press makes the camera screen go blank, and I hear several faint clicks from it. A second immediate press doesn't seem to do anything. It never does actually capture an image.

When I get a chance, maybe I'll post a video of what it's doing. In the next few days, I'm going to pick up a USB splitter and try that instead of the hub.

26 Feb 2011
Well, I tried with a new hub, even wired in the new AC adapter in case the problem was with the old one, and I'm still having the same problem. The problem persists even when I take the hub out of the loop and plug directly into the camera.

I wonder if there's a setup problem with CHDK? Any troubleshooting advice would be welcome.

AS: One way to figure out if it's a CHDK setup problem might be to try interval control scripts to fire your cameras. I use a script which I shared here CHDK goodies. I liked it so much I don't even use a hardware switch now. You may not care for it, but at least if it works it means your CHDK is coming up as expected, and you can start using your scanner while you figure out the hardware issue.

AD: Yeah, I'm starting to think either there's something wrong with CHDK. There isn't something that the camera is waiting for, like the flash or something?

The whole thing seems awfully weird. I mean, if it responds to the hub at all that means that the hub is likely correctly hooked up. If it were backwards or something the thing would probably ruin the USB port. I would dig around and see if you can find remote triggering settings. On SDM they're called "s_fast" or something similar.

AR: SOLVED! It was an issue with the CHDK settings. I played around with them for a few minutes, and everything seems to work now. It was working fine with one camera, then I had a bit of trouble getting the second one to respond also, but both seem to work fine now.

Slides on the platen

I used the cheap Home Depot slides on the platen, and they never did work smoothly. A few days ago, one of them completely self-destructed on me- there were ball bearings bouncing everywhere. I replaced them with higher-quality versions from Rockler, and it makes a world of difference.
Rockler is a woodworking supply store. I've been very happy with them over the years- their stuff is very good quality.

These are the slides I got: item number 29005 is the 14" version.

They're a lot smoother than the HD ones, and seem much better built. And they're only a few dollars more. Best of all, they're the same size, so switching out the old ones is easy.

Final build

On the top right of the page you can see the entire scanner, all set up.
And here of course when it is completely folded and stored ready to be put under my bed.

Here's a close-up of the LED light rig. You can clearly see the 4 [[Cree]]'s and the [[BuckPuck]], as well as a switch I wired in.

The aluminum serves as a lightweight structure as well as a heat sink.

A side view of the light rig:

Ready to scan!

And the whole scanner, including cameras, light rig, and all cords and cables, packed for storage:

Final words

When I designed it, I started with the stowed size—I measured an underbed box, and decided that would be the maximum size of the case. I also decided that I wanted to use 11x14" glass, so that gave me the dimensions of the cradle and platen. The platen stand was just two pieces of 3/4" ply glued together to get the thickness necessary for the slides.

The PVC pipe for the camera mounts and light stand was chosen to be a bit larger than necessary, so that once I had the thing built, I could determine from actual use how long they needed to be, and cut them down if necessary. So you see, I based the size of each part off of some other part—I measured and cut as necessary, and never wrote down any sizes.

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