Possibly a printer like the old Espon Stylus 3000 which has a tractor feed
mechanism could produce more accurate direct prints? I would not be able to
modify and re-engineer the printer to work for this application, but it
seems you would be able to do it.
-----Original Message-----
From:
Homebrew_PCBs@yahoogroups.com [mailto:
Homebrew_PCBs@yahoogroups.com]
On Behalf Of eugenio
Sent: Thursday, June 28, 2012 4:39 AM
To:
Homebrew_PCBs@yahoogroups.comSubject: Re: [Homebrew_PCBs] Re: Inconsistent scaling with Samsung ML-2165
Hi guys, in the last two years i've implemented every imaginable way of
making pcb's at home.
One of these ways was Mark Lerman's direct laserjet printing, when i
finished the printer-machine i realized that the printer was inconsistent in
scaling.
After studying the inners of the machine i saw that the printer was perfect
in the execution, the brushless motor was synced perfectly with laser and
with a perfect constant speed and the clutches were working perfect. The
guilty is the micro-slips of the pcb with the rollers. It can be seen
testing that transparencies are more inconsistent than normal paper for
example.
The easy solution is to harden the springs of the rollers, and the perfect
but difficult solution is to make a carrier with the same speed as the
photosensible roller.
I was able to direct print multiple times in the same pcb and you wouldn't
notice, and i had perfect registration in two sides. I used a fpga to
substitute the sensors stuff of the machine.
For the curious, Mark Lermans's way didn't fit my needs so i discarded it,
but for other problems different that consistency, the most important one
was that toner is not a good resist for plating with 4-5 mils precission.
On 06/28/2012 02:46 AM, godzilera wrote:
> It's not a question of just adjusting the scaling; the problem is that
it's inconsistent. Sometimes it would come out too small, sometimes it would
come out too big...
>
> However I have now managed to print at least three perfect copies using
the HP photo paper by printing my layout at the bottom of the page. This
seems to confirm that the speed of the paper is only inconsistent at the top
of the page. I think that is because the roller that pulls the paper out of
the tray is also responsible for pushing it over the drum, and some slippage
occurs with the thicker and glossier paper. Once the paper hits the fuser
though, then there is enough pressure to pull the paper with a constant
speed.
>
> Anyways, my board has been printed and etched, and it looks perfect. In
the future, I think I will probably cut strips of TTS or photo paper and
tape it to another sheet to make sure I always print on the bottom of the
page without wasting a whole sheet.
>
> In general, I think the straighter the paper path, the better. With the
old HP LJ 4 at the office I used to use the manual feed and open up the
back, so that the paper would not curve up back to the front, but that is
not possible on this ultra-small Samsung.
>
> For now, the little Samsung at $90 works fine as long as I can work around
its limitations.
>
> Thanks,
>
> Pete
>
>
> --- In Homebrew_PCBs@yahoogroups.com, DJ Delorie<dj@...> wrote:
>>
>> When I did TT, my process was to print a "calibration board" and go
>> through all the steps until just before etching, and measure the pcb
>> itself to find out what the X and Y scale factors are. Each step
>> along the way might alter the dimensions somewhat, so it's important
>> to just check the results you care about.
>>
>> gEDA/PCB, btw, has separate X and Y calibration values you can fill
>> in to adjust printouts, just for toner transfer.
>>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and
Photos:
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>
>
>
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