DIY High-Speed Book Scanner from Trash and Cheap Cameras

Step 26 Platen: More on Plastics

Have your pieces cut at a local plastics place. Ask them, if possible, to route the edges smooth. It will make gluing the pieces much easier. If you don't want to glue your platen or handle dangerous chemicals yourself, your local plastics shop can do it for you, but it will be expensive.

Watch this video from TAP plastics, and/or or this video from me. I apologize for the low production quality of my video. If you haven't welded acrylic before, these are a' must watch. I have found that I vastly prefer using a syringe over the usual applicator, but syringes can be hard to find, and you don't want to pull them from the trash. ;)



UPDATE: From Caitifty, how to find syringes: Pharmacies in California and many other states in the US now legally sell insulin needles (and Canada, most of Europe, Australia etc have done so for decades) - get the smallest gauge they carry (smaller gauge = larger diameter, go figure) and you'll usually find the needle part can be popped off by sliding a knife blade into the gap at the head of the needle, leaving you a very convenient syringe with a 15mm applicator tip. If you're really lucky your pharmacy (or needle exchange - google to see if there's one near you) will carry actual luer lock syringes which don't have needles 'built in'.

Comments

[spamsickle]

Just a caution that haven't seen mentioned before, based on my experience. I wanted my acrylic to be protected while I was making the platen, so I only peeled back about an inch and a half of the blue plastic while I was melding two pieces together. For most of the joints, this worked fine, but on one of the endpieces, the plastic flopped back against the joint after I'd squirted the solvent. The same capillary action that wicked the solvent into the edge wicked it up under the protective plastic, giving me a decorative texture for about an inch and a half along that edge. Fortunately I'd already made the length 3 inches longer than Daniel's 15 inch design, so I still have plenty of smooth plastic to shoot through, but I'd recommend either taping the blue protective plastic out of the way, or cutting it off before applying the solvent.

[autophile]

That's a very good idea. My blue plastic was also being floppy. Tape would have helped -- I don't know why I didn't think of it!

[spamsickle]

I don't know how well this will show up in the picture, but here's the "textured" edge. Be careful out there!

[phb]

You can order needles from as well - quite cheaply too - I'm new here so I'm not sure if it's ok to post links, but dealextreme.com/details.dx/sku.22303 = $1.42 for "HD Safety Disposable Medical Syringes - 10ml (2-Pack)" + shipping. Heaps of other cool stuff on that site too: expect to waste a lot time there! HTH....

[daniel_reetz]

Thanks for the DX heads-up. I sent for a pack.

[spamsickle]

After reading the comments and evaluating the quality of the acrylic I already own, I decided to get a couple of new sheets for the large elements of the platen. I'm going with 1/16" (they didn't have 3/32" so it was either 1/16" or 1/8", and I decided to be the guinea pig). They cut two 15" by 18" pieces for me for $14, and recommended Weld-On #4 ($7.50 for 4 oz) and a plastic applicator bottle for $3.80. For a syringe, I'm planning to use one of the syringes I have in my inkjet refill box. I assume the solvent will evaporate out of the syringe before I need to use it again to refill an inkjet cartridge, but I guess I'll be the guinea pig for that too. I'll probably flush it with water before squirting the ink through it, just to be on the safe side. The reason I'm going with larger plastic for the platen is because the wood pieces I salvaged for the VST (shelves from a china cabinet someone has left out for the trashman) are only slightly smaller than that, and because I have a couple of books that big. I will be using 1/4" acrylic on the ends, as Autolite did, but I'll probably weld the whole width of the platen since I'm using thinner acrylic and larger pieces to boot. I don't see a downside to providing extra support/rigidity on the ends, and I already have the 1/4" sheets, so the materials are free.

[daniel_reetz]

Sorry for the late reply, Spamsickle. You shouldn't have any problem with weld-on #4 evaporating, as it's almost entirely methylene chloride, which is very volatile. You should also be alright with your thin acrylic, but be double sure to get a good bond on that long edge. With such thin plastic and such a large platen size, you may see a little flexing, but you should be alright.

[djsc]

In the UK you can get syringes of many sizes from hobby/modelshops without the needles.

[Caitifty]

Pharmacies in California and many other states in the US now legally sell insulin needles (and Canada, most of Europe, Australia etc have done so for decades) - get the smallest gauge they carry (smaller gauge = larger diameter, go figure) and you'll usually find the needle part can be popped off by sliding a knife blade into the gap at the head of the needle, leaving you a very convenient syringe with a 15mm applicator tip. If you're really lucky your pharmacy (or needle exchange - google to see if there's one near you) will carry actual luer lock syringes which don't have needles 'built in'.

[daniel_reetz]

Thank you! May I add this to the platen step? This is really useful information and I appreciate the tip.

[Caitifty]

Oh definitely. And thanks for writing such a great instructable - I particularly love the way you're encouraging people to think about using whatever materials are available to them.

[daniel_reetz]

Awesome, thank you. I'll add it now.