Homebrew PCBs

On 06 Nov 2013 00:34:37 -0800, you wrote:

>
> Has anyone ever simply refed an already printed photo positive transparency to print a second and even a third time, in order to double/triple the density of the ink, thus increasing opaqueness.
>  
> I read yesterday about someone modifying his laser so the paper always fed in the same position. As far as my inkjet goes I have no idea what the system is that senses the paper edges, how accurate that sensing is, and how accurate the paper positioning is once it is sensed.
>  
> Taking this one step further, has anyone made a cnc plotter style printer with an inkjet. This way the paper could just be fixed in position and could be printed on several times (easier said than done I bet).

A bit of ancient history on HP "grit wheel" pen plotters.

There was an article in the HP Journal about paper positioning. IIRC they
stated that the drive wheels pinched the paper quite firmly and impressed
the grit wheel pattern into the paper on the first couple of passes.
Note that the plotters ran the paper back and forth several times before
plotting began. The paper then had a strong tendency to run in the
pattern impressed in the paper for the duration of the job. Once the
paper was ejected all bets were off; there was no hope of regaining the
previous alignment. Far as I know there is nothing like this in
laser printers. They are designed to put toner in approximately the
right place in a single pass. By approximately I mean close enough that the 
customer won't notice any shifts from sheet to sheet. In general, they
were never designed as high precision devices; just "good enough" for consumers.


Keith Bowers WB4LSJ- Thomasville, NC