Homebrew PCBs

On Sun, 22 Jun 2003 01:13:15 -0000, grantfair2001 <grant.fair@...> 
wrote:

> Hi Stefan-
>
> I was wondering about why your experiment failed. Some acrylic floor
> floor polishes have a particle size of 185 nano meters. Some inkjet
> print heads can handle particles of 750 nano meters diameter. So I
> wonder what made the print heads clog? I guess that particle density
> and ink viscosity might be related variables.
>
> Does anyone know an inkjet printhead engineer/ink chemist?
>
> Grant
>

i think you are right.
also a problem may be that the head i used was a thermal bubble jet.
this may be the problem because it heats the ink up in the nozzle and this 
may help in clogging it up.

if you remember i also inspected these heads. behind each nozzle i could 
find two "electrodes" only seperated a small distance.
they were both in the pipe through the head material (silicone?), located 
just under the golden cover foil.

i could not see any "resistor" element in there. so i had the following 
idea:
hp may use the ink as a "resistor". i know this would have some 
disadvantages but also some advantages:
the ink kinds being useful reduced ("buy hp").
if there is no ink in there, if it is clogged before the head it will dry 
up and heat no more.

i have no idea if this is true. if anyone has the right optical tools he 
might inspect a dead head closer by himself.


i gave up so sudden because of the following:

if only one single jet is clogged you get a gap all overthe tracks on the 
pcb, and this every 5mm or so.
i didn't like this idea.


but the head worked with water, and as i put in the polish not one drop 
came through the head anymore.
maybe i try again if i get a really cheap piezo inkjet.


regards
stefan