I'm talking Hewlett-Packard black inkjet cartridges now.
I want to fill #15 and #45 black ink cartridges. These contain bladders
filled with ink. The bottom of the cartridges contain a stainless steel
ball underneath a thin covering (which may or may not admit air). I've
not taken the plunge yet.

I envision the function of this ball this way:
It's a one-way check valve. Its purpose is to admit air in order to make
up the volume lost by the removal of ink through the print head: to
equalize the vacuum caused by the removal of ink. Or something like
that. Come to think of it, if the bladder collapses with ink removal,
why is this valve there at all? Anyway, this is how ball valves are
typically used -- gravity otherwise keeps the ball in place, which in
turn, keeps ink from seeping downward through the hole, preventing a
disgusting, loathsome, unspeakably-foul mess on the paper under the
print heads. Why is this ball there at all? Why didn't HP use a plug?

All the instructions that I've seen for refilling these cartridges
instruct the novice to push the ball into the cartridge, where it will
reside for all eternity. Some kits contain a new ball. Other kits
contain plastic plugs of either or both of two designs:
- A capped dowel
- A tapered rod

Since some people have complained about leaks, I'm assuming that the
capped dowel version doesn't snugly jam the hole, and is not very nice
to live with. The tapered rod is more appealing, especially if it's made
of a semi-soft material that'll jam in the hole and seal it nicely.

So, do the plugs work properly in the real world? Does a person like me
really need balls in order to seal the holes?

Richard

"Richard Steinfeld" <rgsteinBUTREMOVETHIS@sonic.net> wrote in message
news:129cah2s986m81@corp.supernews.com...
The ball is not a check valve, it is a plug. As you surmised, the
bladder collapses in these cartridges as the ink is used. Allowing air
into the chamber would result in ink dripping out the nozzles.

- Bob Headrick

Bob Headrick wrote:
....

Great. Got it. Sounds like I don't really need any more balls than I've
already got. That's a relief (valve?).

Thanks, Bob.

Richard

Richard Steinfeld wrote:
If these are the cartridges I'm thinking (also used in HP 920?), I used
stainless steel set screws after punching in the ball. I don't remember
the size number. No chance of a leak. You can probably Google refill
sites for the size number.

-Taliesyn

"Richard Steinfeld" <rgsteinBUTREMOVETHIS@sonic.net> wrote in message
news:129cah2s986m81@corp.supernews.com...
I refilled the HP 45 black cart for years using a device that pushed the new
ink in through the head. It worked quite well. You sucked the any remaining
ink first to deflate the bladder then pushed in the ink. No messing with
screws and balls.

CWatters wrote:
think that the going price is about $10 USD. This brings up a couple of
questions:

- I'll assume that there'll always be some dried ink particles on the
head in normal use. I'd think that you don't want to push those
particles back through the head. So, do you clean the head before
back-filling? How do you clean it?

- How did you refill your color cartridges?

Richard

Richard Steinfeld wrote:
The only good way to fill a 45 is to use a tool
that fills through the head. No mess, no drip, no
problems. And you don't do anything with the ball.

"Richard Steinfeld" <rgsteinBUTREMOVETHIS@sonic.net> wrote in message
news:129djmokvtj7986@corp.supernews.com...
Not in my experience. It's either clean or wet with ink. The head is wiped
clean by the printer and the heads capped when parked.

I'd think that you don't want to push those
Yes I do clean it - just wipe off the wet ink on a tissue

By pushing in the rubber bungs and injecting direct into the cart. The
colour cart on my 895cxi seemed to be foam filled where as the black cart
isn't.