On Sun, 15 May 2005 14:25:35 -0400, Alan King <
alan@...> wrote:
> 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.
>
Ok, here what i see:
Some liquid is created, which i think also sizzles.
When i remove the board quickly the liquid is still there, and it can be
used to wipe partially toner off the board like a oil or solvent. i dunno
what it is, it is not there with high-temp silicone, no difference how
long you let cure, so i do assume it comes from non-high temp silicone.
>> 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.
I do not agree it is _still_ to sticky. it is too sticky, without still,
it will not get better.
Note i do not use uncured silicone, only fully cured. Silicone stays
sticky even when fully cured.
> 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.
Yes, best to avoid. the lexmark has a uncovered drum, and it can be
installed by stupid people, so i assume normal, short, low intensity light
will not damage it.
> 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.
>
Let me know what solvent you find. I have so far only needed a dry paper
tissue, since i wasn't quite silly enough to put in uncured silicone ;-)
>> I have a problem with creases forming on the last few cm of a page, but
> 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..
I do not have legal paper, but yes, for smaller boards it is not an issue.
I only noticed because of the big geometry test board.
I do not think it is because there are no rollers, the printer is pretty
badly made and there is no wide roller before the drum, like on a HP, just
a small transport to the left. The creases are there at the drum, 'cause
there is no toner in them. they are not really creases (folded/crumpled),
more like vallies in the paper, bent down in a u-shape, and not touching
the drum. Maybe it will go away when i sort out the feed skew. i think the
left edge runs against the guide, and the silicone is too sticky to allow
the page to turn slightly halfway in.
> 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.
A lexmark, and yes, i can compensate in X and Y, but the right Y is
different from the left Y. probably because of feed skew and laser
misalignent, the service manual (such a crap, not even a schematic),
describes how to fix it. I must move the printer from under the table to
on it before tho, and the table is full of ∗∗∗∗, you know the story.
> 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.
you. me it would take a month. I fear i can not use such code and must
compensate before print.
> 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
Customers do not like to use bug style.
Use sheetmetal shears for round boards.
ST