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Words of wisdom

Posted: 12 Jun 2009, 23:04
by jradi
I thought we could post some words of wisdom, learned the hard way.

A. When assembling the acrylic platen, always check that the top of your applicator bottle is on tight before each application. Otherwise, solvent will spill all over your project and mar the surface of the platen.

B. Peel back more than 1 inch from each edge before applying the solvent, and tape down that protective coating. In the event you have said spill of solvent, you want to minimize the amount that might get wicked under the protective sheet.

C. Make your platen LONGER than the book cradle that it will rest in. That way, if you have a mistake on one (or both) of the ends, they will be inconsequential since the book can be placed well away from the ends of the platen. Thankfully I did this by luck. Hopefully it won't make the device too hard to use if the book is a ways inward from the end.

D. I have yet to figure out what the best material is to have underneath, but I can tell you that newsprint will stick to the acrylic if the solvent spills on to it. Once again, if you build your platen long enough, this won't mar the part of the platen that the book rests under. However, if your newsprint or overspill occurs along the long side of the platen (the part that rests along the spine of the book), then you've pretty much made a $20 disaster.

Re: Words of wisdom - sliding drawers

Posted: 12 Jun 2009, 23:09
by jradi
Measure, measure, measure, and assemble the hinges perfectly parallel to each other. Draw lines on the base and the book cradle to ensure they're perfectly parallel to each other. Any mistakes will cause the book cradle to not roll smoothly. I messed up my first attempt.

Luckily, I used really cheap mdf for my cradle and the base so it was only a $5 mistake to put down a new base and try again.

That's the other word of wisdom, mdf is cheap, countertop is not.

Also, the second time I installed the keyboard slides, I installed the second part (that goes on the base as opposed to the book cradle) while it was still attached to the book cradle. I just put the cradle on the base where I wanted it and slid the cradle to one side to install the screws. It was much easier this way.

Another thing, if using the keyboard/drawer slides, assemble the bottom part that goes on the base off to one side. The drawer slides slide a long ways in one direction but not both. If you put the bottom smack down in the center, then you've created a cradle that will easily move in one direction but not the other. Luckily I figured this out before installing anything...

Re: Words of wisdom

Posted: 13 Jun 2009, 00:18
by you1
tnx for the tips Jraid

Re: Words of wisdom

Posted: 13 Jun 2009, 09:39
by rob
My words of wisdom are:

1. Always plan to build another.

2. Measure twice, stop when you're about to make a cut, and measure another twice. Then cut once.

3. A good design is tolerant of mistakes.

4. Never pick up a slug with your bare hands.

Re: Words of wisdom

Posted: 18 Jun 2009, 05:04
by jradi
This won't make sense until I post pictures of my V1.0 scanner, but build the base wide enough so that the arms holding the cameras won't get hit by the platen when it pivots upwards.

I totally missed this dimension, luckily I was able to modify the design a little to get around it but I was a little disappointed in not having caught it earlier. The two things that I did to contribute were (1) made the platen larger than called for, which made it a little wider, and (2) made the base narrow, and therefore the arms were closer together.

Re: Words of wisdom

Posted: 18 Jun 2009, 11:06
by daniel_reetz
Huh. I would have never thought that would be a limiting factor, but I can visualize it easily. Huh.

Re: Words of wisdom

Posted: 18 Jun 2009, 11:21
by spamsickle
On my "manual" platen (not attached to anything), I sometimes hit one of the cameras as I pulled it out of the way. Now, I'm just aware of that possibility, and extra careful.

That shouldn't be a problem when I build 2.0, because I'm planning to have the cameras attached to the platen frame. I wonder if raising and lowering the cameras will (over the course of scanning a book) cause a camera to droop slightly out of alignment, but I hope that it will be possible to tighten all of the screws enough to prevent that.

Re: Words of wisdom

Posted: 18 Jun 2009, 12:12
by daniel_reetz
if there is a point of perfect alignment, I could laser-cut camera supports that would not flex or droop.

Re: Words of wisdom

Posted: 18 Jun 2009, 12:15
by daniel_reetz
I really need to email Ian from the BKRPR group again. A book scanner with cameras mounted on the platen would represent a kind of hardware middleground for our designs.

Re: Words of wisdom

Posted: 18 Jun 2009, 12:18
by Cabe
daniel_reetz wrote:I could laser-cut camera supports

Show off :D

Laser cut critical components would be very cool though.