A desktop Scribe-like scanner

[xorpt]

Hi all,

Thanks to all the inspiration found here, I have completed my first DIY scanner build. It's roughly inspired by the Archive.org Scribe scanner, although I have tried to produce something more compact, to fit in my small apartment. I have a ceiling lamp that is (almost) powerful enough, so I didn't integrate lighting in this build but it could be done easily by extending the vertical sides.

The platen is made of acrylic, fixed by screws to the sides. It is raised by an arm with a counterweight.



The actual thing:





The required material are quite cheap (even here in Japan, where DIY is not the most common thing...) . One sheet of 900x30cm of plywood for the craddle, 2x4cm plank for the frame and 2x2cm for the arm. The craddle sits on drawer slides for lateral movement.

The camera setup is two Canon G7 on tripods (I have first tried to fix them on the scanner itself, but there are too much vibrations caused by the platen movement) triggered with the CHDK intervallometer. I have found 7s. between pictures to be a good compromise for me.

I found that the fact that the craddle is not moving only up and down, but also around the lateral axis is interesting, because you can use it to "open" the book when bringing the platen down.

Of course there is room for improvement... there are quite a few things that I am not very satisfied about:

- I have build put the craddle too close to the rotating axis, so I don't have as much lifting amplitude as I could. I didn't have troubles with it while scanning until now, but it could help when turning pages of larger books. But this is not a scanner for very big books.
- Acrylic seems to wear off a little by always rubbing against the pages... it means I will have to change it after some time.
- I have built everything with wooden dowels for esthetics, but I don't know if I'll keep doing this too much a hassle compared to screws.
- the wood of the craddle is too slippery so the book moves back and forth. I will have to put some grip material on it.
- the zoom function of the G7 is not the most precise I've seen... to fast, with big "steps" that do not allow precise framing. It's difficult to get the same scale on images on both sides. If someone knows how to fix this, it's one of my main issues.
- if the tripods are not carefully set they give reflections on the platen.

[xorpt]

I have added two major improvements to my scanner:

- a grip to the craddle... VERY nice. the book does not move anymore

- a wet towel I touch it before turning pages with the index and thumb... and I do not miss any page anymore. Talk about innovative scanning technology

Now I need to add something like a black fabric for wrapping the cameras and eliminating their reflection.

[sixtysix]

I love the simplicity of that design. Can you explain what is
the purpose of the arrangement on the back of the arm that is holding the platen.
Also how is the arm attached to the main frame.

thanks

[dpc]

Now I need to add something like a black fabric for wrapping the cameras and eliminating their reflection.

I love this stuff: Cinefoil

[Gerard]

i would recommend something none flammable (black fabric used on stages) in german it's called molton http://dict.leo.org/ende?lp=ende&lang=d ... rch=molton

[xorpt]

I love the simplicity of that design. Can you explain what is
the purpose of the arrangement on the back of the arm that is holding the platen.
Also how is the arm attached to the main frame.

thanks

Hi,
the thing on the back of the arm is the counterweight . Since I had some wood left from the main frame I used it to make it easier to lift the platen. Basically you could use any stuff you like instead (like fishing lead sinkers or lead for diving, etc.). I think that the counterweight must not be too heavy, or it will lift the back of the platen when it is in down position (or you'd have to weight the back of the platen too, that could do it I think), and of course not too light, or it will be harder on your muscles

The arm - main frame junction is very simple: a hole on both side, and a metal dowel used for shelves, like these ones, only a little longer



it works like a charm...

@dpc and Gerard: thank you for the advices, I will look into that.

[xorpt]

Another improvement to solve one of the issues listed in my first post:

I have made a CHDK script (I know, the code is awful... sorry for the real programmers among us) that allows me to set the zoom one step at a time (the G7 has 14 predefined zoom steps) using the "left" and "right" control buttons and refocus automatically each time. It is now much easier to set the cameras correctly.

Code: Select all

@title zoom controller
@param a = zoom
@default a 1

if a < 0 then a = 0
if a > 14 then a = 14
 
set_zoom a
press "shoot_half"
sleep 1000
release "shoot_half"

s = get_zoom_steps
print "max:", s

do
wait_click 1000

if is_key "right" then
	cls 
	get_zoom z
	z = z + 1
		if z <= s then
			print "zoom:", z
			set_zoom z
			press "shoot_half"
			sleep 1000
			release "shoot_half"
		else
			print "max. value reached"
		endif
endif

if is_key "left" then 
    cls
	get_zoom z
	z = z - 1
		if z >= 0 then
			print "zoom:", z
			set_zoom z
			press "shoot_half"
			sleep 1000
			release "shoot_half"
		else
			print "max. value reached"
		endif
endif

until is_key "set"

BTW, the book "The Canon Camera Hackers Manual" by BERTHOLD DAUM is quite good. The same information is available on websites, but this book puts it all in order.

[daniel_reetz]

Congratulations on a really beautiful build.

[xorpt]

I'm adding the Google Sketchup file for this scanner build.