Stefan Trethan wrote:
>
>
> Nah, i still don't like the idea. I tried to run it through the fuser to
> evaporate this liquid, but it doesn't work.
It'd take many many passes at a desired temp to dry it. You generally use a
somewhat higher temp to proof something against the desired temp.
> I think the temperature is just enough to break down normal silicone. I
> think it could work to reduce fuser temperature, because it seems at the
> beginning of a board (when the board is coldest) it doesn't sizzle.
Sizzling almost guarantees you still have liquid turning to gas and escaping
through the other parts of the material. Dry solids just melt. Silicone is
relatively inert so unlikely it even has a melting point that low, I'd find it
very hard to believe that the gas temp is anywhere near toner melting temp.
Melting hardly expands anything, almost has to be gasses if you're hearing
sounds, which implies remaining liquid.
>
> Whatever, using normal silicone is not a priority for me. High temp
> silicone works and i accept the doubled cost for now, after all fiddling
> around with the temperature is a lot of work too. Right now i'm fighting
> with the printer for perfect geometry adjustment.
>
But yes it's relatively dirt cheap anyway with how much you can cover. And
the real goal is ease so cooking is sort of a step backwards even if it works.
But with 15 mins plus of leftover heat every time the oven is used it may be
easy enough to try.
> The things concerning the transfer so far are:
>
>
> Do not put silicone on the first 7-10cm of the page or you will from then
> on have a paper coated drum.
> (By the way, drums and light-sensitivity, how bad is it really? which
> precautions must be taken when working with drums?)
>
LOL Been there done that. If it's even sticky enough to do this though I
think it's still maybe too sticky. If the only reason it's coming off the drum
is because that first 7-10 cm is pulling it off with other rollers, then little
bits are still probably sticking to the drum. May be a livable situation though
and just consider a new cartridge now and then a part of the ease of transfer,
it'd be $20 well spent for perfect transfers with little work. I can make mine
near perfect with the other papers, but the process is more tedious and I
usually say screw it and just touch up any problems.
And the answer for light is very, very sensitive. 600X600 is 33 million
pixels per page. So 10 seconds per page that laser is sweeping about 3+ dots
per microsecond. Fractions of millionths of a second per pixel, times the 2500
or so pages the cartridge is rated for, that's all the light that's supposed to
hit the drum. Any exposure to light degrades the whole drum evenly though, and
I think there is some recovery effect too. The lasers are red or infrared, so
that's what the drum works off of. The color it mainly reflects (green or blue
depending on type) should be more safe at low intensities than just white. I've
thought about making a green and blue single LEDs safelight for working with them.
I think the degrading though is not 'black image' but leaky drum so less dark
image from less attraction. Since it only takes a tiny bit of plastic to
protect the copper I doubt a poorer drum that makes lighter prints would pose a
problem really, whereas for prints you can't make your blacks look dark enough.
Still best to avoid of course.
The coatings are organic, so organic solvents are a no-no. I'm trying to
find the inorganic solvent they use to clean them, it should let me recover my
wrapped drum since what's remaining isn't stuck too badly. Had a friend in a
copier shop that knew all the details, but haven't gotten in touch with him yet,
and I don't remember which solvent was for what they also stripped typewriter
drums etc.
> Work with relatively low pressure in the fuser.
>
> Let cool before peeling off the paper.
>
> Otherwise the results are pretty good.
> I have a problem with creases forming on the last few cm of a page, but i
> hope to figure that out, and also for small boards it is not an issue.
> Also, if this particular printer gets eaten up by acetic acid i do not
> care that much, more like hope nothing is left...
>
Sounds like the back end of the paper is no longer in rollers, and this lets
it shrink. Maybe try a legal sheet with another 7-10cm on the end with no coating..
> It also needs to be cleared if the acetic acid does remain on the surface
> of cured silicone. I have wiped it with acetone to re-use and that does
> not seem to be a problem at all.
>
>
> Much of my efforts is going into the distortion thing at the moment, to
> see if i can go ahead with the CNC or if there is no point.
>
What printer are you using? There is a small amount of distortion in my 6L's
but it's so small I don't worry about it much. Because of the rotating to
linear conversion it'd be hard to be 100%, but it should be possible to map the
distortion and precompensate the original before printing. And what for the
CNC? If you're just talking drilling alignment etc, then use two opposite
corner holes and manually locate them. From where they are to where they should
be will tell you exactly what your scaling error in X and Y is, far easier to
compensate by math for the drill hole locations and simply match what your
printer puts out. The absolute error is small, doesn't affect any components
I've seen.
Of course if you have to have 100% exact dimensions then it much be
precompensated. Just for a general circuit board though a percent or even a few
doesn't matter as long as the holes are matched..
And with 3 corners (two opposite and one of the others) you can get accurate
scaling and rotation information. Align the three manually for their actual
locations and you can find all the other holes without even aligning to be
parallel to the axes. Some basic trig is all it takes.. But it's so easy to
move side to side and use two holes to be exactly aligned to X, then go up to
the corner and get scaling, that I only do the 2 corner scaling and align to
parallel manually. LOL really just lazy and haven't written the code for 3
point with rotation, wouldn't take 15 minutes to do it.
I am starting to work on the CNC again some for cutting more than drilling,
so maybe I'll write it up soon. Hardly even used the CNC for anything since I
started just making everything single sided and mount all DIPs etc live bug
style without any holes. So much faster to just not drill anything at all. But
nibbling out circular boards is a pita, so time to get it back up for my board
routing.
Alan