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

Collapsible scanner made with waterjet technology.

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.
univurshul
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Re: Collapsible scanner made with waterjet technology.

Post by univurshul » 15 Jun 2010, 04:02

I like the aluminum aspects of the next build. I was quoted $38 for a 2x2 sheet of 11 gauge cut into 2 1'x2 sections. I want a scanner base to fold in half, and open and lock when in use. I still like the milk crate for my cradle, but having a collapsable cradle is a great idea, as long as the platen folds the same way too.

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daniel_reetz
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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 16 Jun 2010, 01:32

Thanks for the ideas, guys.

So, as for today's progress, I don't have too much on the scanner itself. With the help of a local friend, I was able to find cheap activated charcoal to make a filtration system for my laser. I'll be picking that up tomorrow. I also got a pretty solid start on interfacing my laser cutter to the chimney on the fireplace in my apartment, though it's not hooked up yet.

Basically, what's happening now is I am trying to get the laser going. Though the final parts will be cut on a waterjet, the laser and waterjet have comparable kerf and other cutting properties, so I can test-cut the entire thing on my laser first.

Getting the laser going means:

*1. Finding a fan. Found one at APEX.
*2. Finding a compressor -- the type used to aerate ponds (Hi-flo, low-pressure). Ordered, in the mail.
3. Interfacing to the fireplace. This is a challenge, I think I may have a workable solution as of tonight -- but I'll need tomorrow to finish it.
4. Hooking it all up and verifying that the laser is still in alignment. If alignment is off, I will lose at least one more night. (agh!)
5. Software issues, if any.
6. For plastics, a charcoal filter. I'd previously made one, but it didn't work well because the exhaust didn't have a lot of "dwell time" in the charcoal medium. This time, I'll be routing it through essentially an entire 5 gal pail of charcoal, which should kill most plastic odor.

*=done

No more pics to show at the moment. Possibly more to share tomorrow.

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Re: Collapsible scanner made with waterjet technology.

Post by rob » 16 Jun 2010, 08:56

Now there's something I thought I'd never see: Dan in a workshop but not in a parka!
The Singularity is Near. ~ http://halfbakedmaker.org ~ Follow me as I build the world's first all-mechanical steam-powered computer.

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daniel_reetz
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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 17 Jun 2010, 10:41

I couldn't help but laugh when I cleaned my closet out in Fargo. 80% of it was comprised of sweaters and coats. I brought like 2 light shirts and 2 pairs of pants... so far haven't needed anything else.

Got my laser up and running with a temp setup last night. Not happy with it yet, but it will have to do. Gotta start cutting stuff ASAP to keep on schedule.

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Re: Collapsible scanner made with waterjet technology.

Post by rob » 17 Jun 2010, 11:28

Muahahahaha! My robotic snake arms of DOOM will attach this LASER to this CHIMNEY and transmit FEAR into the BRAINS of ALL pathetic humans! NONE shall stand in the way of CONQUEST! Aha! Aha! AhahahahahahaHAHA!!!
The Singularity is Near. ~ http://halfbakedmaker.org ~ Follow me as I build the world's first all-mechanical steam-powered computer.

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daniel_reetz
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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 17 Jun 2010, 11:36

MUAHAHAHAHAH!!!!

So, I called the waterjet cutting place this morning to learn a bit more about making parts. there was good news, and there was bad news.

The good news is that they can cut approximately 25 linear inches per minute in 3/16" aluminum. That is, I think, four times as fast as my slow-ish laser can cut plywood.

The less-than-good news is that the kerf of the waterjet cutter is not as fine as I was told. It is about 40 thousandths. For comparison, the laser is 5-7 thousandths. So the parts will not transfer 1 to 1.

The better-than-bad news is that the shop I'm working with is extremely experienced and can compensate for this craptastic kerf by routing the water stream alongside the curves. However, this means that I cannot haev any dimensionally critical parts sharing a line, as I would often do with the laser.

The interesting but not horrible news is that curves take longer to execute than straight lines, and that inner holes take more time because there must be an additional "pierce" (which simply means repositioning the waterjet cutting head and striking the metal surface with the water to begin the cut).

Well, so far, so good, I guess.

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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 18 Jun 2010, 13:37

More information, this time regarding the electrical side.

Well, one of the first lessons you learn as a wannabe electrical engineer who ACTUALLY BUILDS STUFF is that all the calculations in the world don't mean anything. The real world is real; not an abstraction, and things are often not what they seem. In spite of the time, effort, and expertise put into the last LED lighting system for book scanning, there were still some things that didn't match the calculations. In particular, the current going to each LED was around 400mA, which is not driving them very hard. They can, in fact, be driven at around an amp.

The way the circuit is constructed, there are two "branches" of 5 LEDs in series. These "branches" are each being supplied with around 400ma of current each. Each LED is receiving around 3.2V. The Vf (forward voltage) or drop of each LED is dependent on the desired current draw, or actually, the desired current draw is determined by the voltage your'e driving at. In this case, at 3.2V each, I was under-shooting the target of around 700mA (yielding about 150-170 lumens at each emitter).

Blah blah; it's an easy fix. I can just drop out a resistor on each bank or one LED and I'll get the kind of voltage and current I'd originally desired. And since I was a bit muddled about current and voltage requirements, I can also buy somewhat cheaper power supplies and DC-DC converters and they'll work just fine. At this point, I'm thinking that 24V, 2A supplies and DC-DC converters might be sufficient. I may go 3A just to overshoot the target and guarantee reliability, which is just a good idea, generally. Wolfgang recommends overbuilding by 20%, but 50% is more the kind of AK-47-like reliability I'd like out of this thing.

What is the lesson here? No amount of circuit design, vetting, and abstraction beats actually building something and then measuring it.
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daniel_reetz
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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 20 Jun 2010, 11:59

Looks like it's possible to buy tempered glass panels for relatively cheap:

http://www.staples.com/Tempered-Glass-P ... _SS1037421

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Re: Collapsible scanner made with waterjet technology.

Post by daniel_reetz » 22 Jun 2010, 23:58

I've been working the last few nights on a scissor-based platen raising mechanism. The idea is to eliminate the drawer slides from the scanner entirely. Drawer slides are easy to gum up, hard to find, and grit-sensitive. Right now my thinking is that It is better to convert all sliding mechanisms to pivots and wheels, which are easily made and easily aligned. Anyone can drill a hole... not anyone can make a nice linear mechanism. I learned this from Suryandaru's scanner a long time ago, but I've never applied it until now.

So, here is my new platen raising idea. It's nothing more than a standard scissor lift. My brother (pictured) is in town, helping me design and test things. Also helping me drink beer and settle down, as the stress of building things and getting around LA is starting to get to me a bit.

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benjamin
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Re: Collapsible scanner made with waterjet technology.

Post by benjamin » 24 Jun 2010, 20:45

i worry that scissor lifts might bind over time. this might be the first scanner to require regular lubrication & alignment. maybe it's a problem only in my head, or one that could be cured by creating a slight groove/track for the wheels?

if it's to be used with a car battery, perhaps time to consider a "flash" (or some kind of off cycle) rather than continuous lighting?

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