DIY High-Speed Book Scanner from Trash and Cheap Cameras

Step 27 Platen: Assembly, Loosely Put

Assemble your platen as shown. Leave the plastic/paper covering on as long as possible. If you make even a small scratch on the imaging surface, that will be in every scan you make, forever.

Comments

[hey_chief]

Rock hound shops, a craft store like Michaels, jewlery supply shops and even a friendly jewelry repair location might be able to provide small amounts of polishing compounds like cerium oxide or jewel's rouge. Check compatibility on scraps. If you are into trading services, rockhounds often like images of mineral collections (no need for platen) and coin, stamp, and jewelry collectors need accurate records of their collections for insurance purposes. Trade for polishing compound.

[jradi]

I'm curious if anyone had any problems with this step? I'm looking to gain some wisdom before I give it a shot, the acrylic's pretty expensive! My initial reaction was to use the thickest acrylic possible, 1/4" for all pieces, but I saw from someone else's experiment that it led to too thick of a joint at the spine of the book. From the TAP video, it looks like its pretty important to sand the edges perfectly smooth before bonding? Also, did anyone use something besides a medical syringe for application? Finding a needle sounds like another huge hassle I'd like to avoid...

[daniel_reetz]

Sorry for the late reply, jradi. I've made a total of 4 platens using various schemes, so I have a little input. 1/4" for all pieces will cause you problems. It is just too thick. For many books you will not have enough room to see into the inner margins. I highly recommend 1/8 or 3/32" acrylic. The endcaps can be whatever you want. Sanding the edges is not important. I haven't done it yet. As long as your plastics supplier does a half-decent job of cutting, the blade marks from the saw aren't a problem. There is an applicator that you can buy, too. I use it in my video. I bought an applicator full of methylene chloride for about $10.

[you1]

Daniel,
Have you tried/considered using acrylic sheets with scratch resistant coating?
http://www.k-mac-plastics.net/polycarbonate-scratch-resistant-sheet.htm
I scratched mine while clean it.

[daniel_reetz]

I used some "scratch resistant" Lexan in my first platen, and it scratched pretty easily. Maybe the stuff you found is better? It's hard to say without a sample. It is definitely true that some acrylics scratch more easily than others.

It might be possible to polish out any scratches if they are not too deep. I see that there are a lot of products like this one:

http://www.watchpolishing.com/plasticpolish.htm

At the moment, I only clean my platen when absolutely necessary. When I have to do it, I use a microfiber cloth and a bit of ammonia-based cleaner.

Ultimately, for durability, we may have to use glass. :\

[jradi]

There's a cheaper solution to polishing acrylic, I learned it somewhere on the net years ago. Plain and simple. Toothpaste and a soft clean cotton cloth. Toothpaste is a very mild abrasive, rub it in a small circle to polish off any scratches, works like a charm. Also works well on watch faces (which is how I learned of it first) and motorcycle helmet visors.

[you1]

Very cool, thank you for sharing. I'll give it a try.