DIY Book Scanner mechanical trigger instructions

[rob]

I'm trying to document putting one of these together, since it's not in the instructions.

First, get one bicycle cable, one thick trigger support, one thin trigger support, and one finger. Here's the cable and thick part:

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Put the end of the cable with the ring on the end into the curved groove like this:

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Put the thin part on, and drill a 1/8" hole:

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Screw together gently with a 3/4" wood screw:

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Put the finger between the supports like this:

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And use a bolt and nut (gently tightened) through the holes:

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Finally, drill a 1/8" hole in the finger to the right of the cable and as high up as you can, and use a 1/2" wood screw and a small washer (washer isn't in the parts list, just find a relatively small one) to squeeze the cable between the finger and the washer:

IMG_0176.JPG (125.73 KiB) Viewed 4016 times

OK, so if you unravel the bicycle cable now, you should be able to pull on the other end and get the finger to press downwards. It should be a relatively simple task of mounting your cameras, finding the best position for the trigger support, and screwing it into the camera mount. You can use the mini bungee cords (they're about 6" or 8" long) from the bungee cord assortment (if, that is, you got it from Home Depot), and attach them to the curved section on the right side of the finger.

For the other ends of the cables, you need to attach those to the dual cable bicycle brake lever, and unfortunately I haven't figured out how to do this very well. Perhaps someone who has built this can explain?

[Imagerlus]

Hi Rob. I like the mechanical trigger, and I plan on making a couple out of plexiglass. Is there a plan somewhere so that I can get the shape and measurements for this part. I would like to avoid guestimating if possible. Thanks in advance for your help.

[rob]

The specs for the mechanical trigger are in the 0.9.10 distribution.

[jefflee]

Rob, thanks for the instruction.
I modified mine a little, I found that the piece that's clamping the bike cable interfere with the pivoting arm when it's screwed down tight.
also I made an arm that fits my camera better, and glued on a piece of soft eraser to reduce the chance of scuffing the trigger button.

[rob]

Hmm. There must be some way to make the cable loop around the screw instead of having to clamp it down.

I think modifying the finger to fit your camera is always a good idea

I also found that for my chosen camera, the finger is actually too small. I'm going to see if I can make another finger that is 6 inches long, maybe also include that in the wood parts.

[mellow-yellow]

Rob et al,

When connecting the bike-brake housing to the lever, I can't get the brake to move the cable properly. I'm not a hardware person (I intentionally haven't drilled the holes shown in the photos above), but any help on this step? Other setups (e.g. http://diybookscanner.org/forum/viewtop ... 8&start=20) show the cable ends reversed, with the metal ball-looking piece coming out of the "thick part" (like in my photo below, as opposed to your photos above). Any thoughts on how to proceed? Am I missing an explanatory thread elsewhere?

[rob]

The cable shown in the post you referenced is not the same as the cables we used or the ones you have!

First, reverse your ends so that they look like my pix above.

Next, take the other end and hook it into the bicycle brake. The large funny-shaped metal thing which is loose on that end goes outside the handle of the brake. It doesn't seem to serve a purpose.

Now, the key is that this thing won't work unless you secure the black cable to something that is fixed in relation to the bicycle brake. That is, you must put the bicycle brake on the scanner handle, and then use a little cable clamp to secure the cable to the scanner handle plate. Then, and only then, will the finger move when you squeeze the brake.

[mellow-yellow]

Thanks Rob! Below, I've attached a quick video (mostly as notes to myself), but how do you hide the clamp? Mine is a big ugly green thing. I must be missing something simple. Also, is it a bad idea to clamp to the top portion as shown in the video?

[dpc]

There's something getting lost in translation here.

The cable shouldn't need to be clamped against the arm. The inner wire cable just needs to be the correct length with respect to the black cable jacket. If the cable jacket is fixed at both ends (clamped by the two halves of the wooden trigger on one end and butted up against the threaded cable adjustment screw on the lever housing), it will work just fine. Have a look at the front brake cable on a bike sometime. Those cables come out of the brake lever housing and right down to the caliper arm. There's no clamps between the two - only the cable adjustment screws that the jacket pushes against.

The problem that I see with mellow's set-up is that the cable wire is much longer than the jacket. What he needs to do is attach the cable to the lever, butt the cable jacket into the lever housing's adjustment screw (screw the adjustment screw all the way in), then feed the other end of the cable jacket into the trigger mount and clamp it down between the two halves. Finally, pull the wire cable snug and attach that to the trigger arm with the washer and screw. The cable adjustment screw on the lever housing can help you tighten things up a bit once both ends are attached.

By the look of it, he's going to have a bit of extra wire cable sticking out above the trigger arm washer/clamp, but that can be snipped off and the cut end secured from fraying (a wrap of tape, solder, small crimp-on lead fishing weight, etc.).

[rob]

Yes -- that's one thing I should have mentioned, that you need to slide the cable housing all the way towards the brake lever, and then you can adjust the finger end of the wire.

However, even when I did that, it wouldn't work without a clamp. I showed the brake lever and brake cable with the finger to several bike people, and they couldn't figure out how to make it work. The only way it would work for me is to clamp the cable to the scanner. dpc, if you have pix or a video, they would be much appreciated.