Andrew wrote:
> Yes - Rotating drum. Single Laser. 15 minutes
> a page kinda thing. Just a rehash of the one
> John Elson (pico systems) did.
Sounds like fun. I'd like to have a go at building something like that myself.
Could be kinda neat to play with photo-etching.
Apparently you can use UV LEDs to expose PCB photoresist - there was an
article in Elektor about it. They modified a plastic storage bin by adding a
PCB with some UV LEDs to the bottom, then putting a plastic (or maybe it was
glass) sheet on top.
I'd be tempted to get a bit of MDF and make a custom box for it, then rig it
to expose both sides at once.
> I hope to make it cheap and easy enough for
> anyone to make with mainly parts you could get
> at places like Jaycar. (cheap and easy are
> relative terms I know :D)
The hard part is going to be finding the steppers, and focussing the laser
down enough to get a decent amount of resolution out of the film. I haven't
seen any laser pointers that can be focussed down below 1mm...
> It is
> coming along very slowly as it also has to
> share my time with other projects.
Heh, I know how that goes.. I've got a battery charger on my workbench waiting
for some serious debugging work to be done on it. I need to smooth out the
current sense line to try and get the regulator to stabilise. Switchmode PSUs
are neat, but annoyingly difficult to get working reliably.
Even bought a pack of Energiser 2500mAh AAs to play with (but I'm doing the
development work with a Kodak 1600mAh that seems to have lost its mate). Both
the Energisers and the Kodaks are rebranded Sanyo cells, to the best of my
knowledge. Easy way to tell (on the namebrand cells anyway) is to look for the
text "-H-R-" stamped into the negative contact on the battery. That only
applies to name-brand cells though (Duracell and Energiser mainly) - a lot of
unscrupulous Chinese manufacturers are doing their best to clone the Sanyo
cells, as cheaply as possible. Which generally means the "2500mAh" clones are
only good to about 1500mAh at best, and the delta-peak isn't as pronounced, so
the chargers tend to miss it and end up overcharging the cells.
>> Or is it the classic X-Y table with a light
>> pen ?
>
> God no - that sounds WAY too hard.
XY isn't that hard - I've got a few scribbly designs and CAD drawings here.
What is hard is taking XY and adding Z axis control too (i.e. for a CNC drill).
I want to make a CNC drill, but I need to get my mitts on another pair of
stepper motors (preferably Laserjet II or III steppers, so I've got a matched
pair) and a decent power supply. Then I need to track down some nice, smooth
slides and a leadscrew (or something similar) to move the tracks around...
> Red sensitive photoplotter film. It has
> "dual sensitivity" at 635 and 680 nm I think.
> Whatever the wavelengths are for common HeNe
> and solid state lasers are.
Where do you get that stuff from? I've never seen it for sale anywhere...
How do you develop it anyway (in fact, do you need to develop it at all)? I
did a bit of B&W photography a while ago, so I'm thinking of this from a "how
is photoplotter film different to B&W film/paper emulsion" perspective...
> I think it works out something like $5-6 for
> a sheet a bit bigger than A3 size. I can't
> quite remember exactly though - and I don't
> have the details here.
So that's what, $2.50 an A4 sheet, or $1 for the average Eurocard sized PCB?
> Does anyone have some spare time they can
> lend me :D
Sorry, I let someone borrow my last Round Tuit and they still haven't returned
it. In addition, my supplier of Round Tuits has been out of stock for the past
ten years :)
Thanks.
--
Phil. | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder
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