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Re: Trigger Challenge

Posted: 10 Jun 2012, 08:39
by fitterman
Dan/Rob, what's a good source of information for routing the cables around?


Re: Build Thread for the Hackerspace Scanner Kits

Posted: 10 Jun 2012, 09:49
by daniel_reetz
There isn't much that I can find - I posted some in the form of pics of the original prototype, which had home-made loop clamps holding the cable. Likely the best source would be completed builds of Rob's kits. I searched a bit myself and couldn't find very much (most people seem to be using electronic triggering).

I can draw something up or make a video later. Just a little burned out on documentation right now.

Re: Build Thread for the Hackerspace Scanner Kits

Posted: 10 Jun 2012, 10:38
by rob
Dan, the videos you posted were great. It's kinda funny how both you and I stopped the instructions at the same point. However, anyone making a video (or anyone wanting to use the mechanical triggers) is definitely urged to go look at the trigger assembly post.

The trigger assembly post, however, covers only assembling the triggers themselves. It doesn't cover hooking up the cables to the brake lever, or attaching the triggers to the camera supports.

Some things to keep in mind that your video should show:

1. Put your cameras on the camera supports without the triggers first, and in non-paperback mode.

2. Put a sample book in the cradle and lift the book up to the glass.

3. Adjust the camera so that the page is centered left-to-right in the viewscreen. Tighten the camera down.

4. Now you can take one trigger and position it so that the tip of the finger touches the button. The trigger might work best on one side or the other side of the camera, it doesn't really matter. Also, even if the cable has to make a somewhat tight turn, it shouldn't matter that much. Bicycle cables are typically teflon-coated on the inside, so they're very slippery.

5. Before you permanently attach the trigger, take one of the felt dots and put it on the end of the finger. You might even want to take some scissors and cut the felt dot down a bit so that it fits right on the camera button. Glue the felt dot to the end of the finger.

6. When the glue is dry, position the trigger again, and here's the hard part: drill two countersunk holes from the bottom of the camera support into the trigger. You will have to drill them so that you avoid the cable. It's also a bit difficult to position the holes, since there's not much to visually tell you where the holes should go. I managed fairly well by taking a small ruler, determining the position of the trigger relative to the edge of the support, adding about half the width of the trigger, and transferring that measurement to the underside. Taking a pen and going around the outside of the trigger on the top side also helps you position the trigger in the right place again in case it moves.

7. Attach the brake lever to the book scanner handle. You'll need an allen wrench to tighten the machine screws.

8. Fit the nub thing on end of the cable into the brake lever. I found that it just sort of hangs in there, with no support. You will then need to use a cable clamp for each cable and locate a place on the handle plate (I forget what Dan called it) to clamp down the cable.

9. Use a small bungee cord and wrap it around the camera support and the small end of the trigger finger (the end opposite the camera). This causes the finger to rise up, pulling on the cable.

10. Squeeze the brake lever and watch the action. You will need to adjust the trigger side of the cable so that the finger lies just above the button when you're not squeezing. That way, it will only require a little squeeze to trigger the cameras.

11. You're done. Dance like nobody's watching.

Re: Build Thread for the Hackerspace Scanner Kits

Posted: 12 Jun 2012, 13:19
by fitterman
I've called a couple of places to see if I can get the glass cut with an edge beveled at a 47.5-degree angle to form the 95 degree joint. So far no one is able to do this, although one place said they could send it out to a factory. I heard a lot of dollar signs sprinkled throughout that sentence. Dan, where did you get your glass cut with a bevel? How important is this?

Re: Build Thread for the Hackerspace Scanner Kits

Posted: 12 Jun 2012, 14:53
by daniel_reetz
I beveled it myself, and it wasn't very good. Honestly, the beveling is not very important. It helps you get deep into books with very tight gutters, but that is about it.

I have two angles of attack on this. One is that I am working with a local glass house on getting a perfect bevel. So far, it is not looking economical. Even for 1/8" glass it is in the hundreds of dollars for two pieces. The second angle is to simply have them beveled at 45 and live with the error. This is OK but so far I've had problems with chipping at the "sharp" edge of the glass, so I'm not a big fan.

So it's clear, other than these experiments I've never had beveled glass, and I'm going to officially un-recommend it for the moment. My current recommended alternative is to put the two pieces of glass in place so that they touch tangentially at the apex of the scanner. Then put either a 1/8" square-profile piece of black painted wood (available at hobby shops in the form of balsa wood for airplanes) or 1/8" black-painted wooden dowel or plastic rod (again, available at hardware, art, and hobby stores). This will prevent optical problems with the edge of the glass and also provide a smooth and safe surface for the book to press against. Terrible drawing attached.

I will work on getting a good self-adhesive version of this with square stock over the next few weeks. People who purchased the first round of kits will get one if it works out.

Re: Build Thread for the Hackerspace Scanner Kits

Posted: 12 Jun 2012, 17:23
by dpc
Let me ask what is likely a dumb question...

What would happen if you took a black magic marker and colored the glass edges, then let one of the panes slide down an 1/8" so that you end up with that perfect corner?

Camera mount bolt specifications

Posted: 14 Jun 2012, 11:53
by wambold
In the video, you mention a 1/4" x 20 bolt for the camera mount. How long should it be?

Re: Build Thread for the Hackerspace Scanner Kits

Posted: 14 Jun 2012, 13:38
by daniel_reetz
1" should be plenty. The wood is .71" thick, leaving .3" to go into the camera mount. You may need a flat washer or two in case it is too long.

Nuts for camera bolts?

Posted: 16 Jun 2012, 14:21
by wambold
Don't you need some nuts (wingnuts) for the camera bolts as well?


Re: Build Thread for the Hackerspace Scanner Kits

Posted: 17 Jun 2012, 06:05
by fitterman
No, you just need the bolts. Each goes through the mount on the scanner and right into the camera. Just don't force them: if the bolt is too long, use a washer or two to make up the extra length.