On Tue, 24 Jan 2017 15:13:12 -0800, wrote:

I made up a little cylindrical reservoir that is pressurrized by a
piston. I tried the injector with some oil that was thicker than the
lube I intend to use. The result was oil that just dripped from the
injector. An online look at DIY injector service made me wonder if the
filter was restricting the flow so I removed the filter. Then, using
oil thinned to the approximate viscosity of the real lube, I tried the
injector again. It squirted pretty good at 30 PSI.

Is that with the filter back in place? With more viscous liquids,
temperature can make a large difference, so keep that in mind, as
well.


The next thing to
address is the reservoir. I'm not sure if a piston sealed with an
O-ring is the best solution for applying pressure. There might be
stiction of the O-ring so that the piston may not move smoothly enough
causing erratic fluid delivery. An inflatable bladder would probably
work well but I have no idea where to get something like that. I'll
have to see if there is some sort of cup seal that would work better.

I'm not sure how small they go and what diaphragms they use (oil
proof?) but well water pumps work against a pressurized tank to
maintain pressure. The membrane separated the air from the water.

Lincoln had an accumulator in their brake systems on the Continentals
way back. Brake hydraulic pressure was run through the steering pump
to activate the accumulator, providing assist to the brake master
cylinder, giving you a lighter pedal. (Most cars use vacuum assist for
power brakes.) IIRC, they were about 6x6", but they might be too
pricy for this. I don't know if they could be utilized in a
lower-pressure format, or run in reverse (I never took one apart to
see the innards), but you could check.

What kind of volume are you going to maintain? What size reservoir?


In any case I don't think it's a good idea to have the lube exposed to
the shop air, even though it's filtered, because there will always be
a little moisture in the air.

True. Moisture and oxidation are not your friends.


When I need pristine air I do have a
nice refrigerated air drying system with particle filters but I don't
generally use it.

Why not keep the reservoir enclosed, away from air? I suppose it
depends on how finicky your specific cutting fluid is.


The other thing I need to chnage is the spray
pattern. Not sure how that's gonna get done yet. Maybe just a
deflector slipped over the injector will work well enough and that's
my first option. I've got a 555 timer system running and I will be
weighing the oil squirted out once I have the pattern deal figured
out.

Maybe a toothed curve to allow small droplets to spread out the
diverted oil as it drips off. What tip style did you say you had?


Once that's done then the timing can be set. I'd like to have
some sort of knob to turn that has a linear relationship to the amount
of fluid delivered. So that a setting of 4 would be twice as much
fluid delivered as a setting of 2.

_That_ you'll have to play with, numbers vs full turns.
Run it and measure, charting the output at various temps and
viscosities (if those vary). Optimize the pulse width with the 555's
RC circuit values, right? That's the fun part, once you have a new
device working.

--
"When the people fear their government, there is tyranny; when the
government fears the people, there is liberty."
Attributed to Thomas Jefferson, but Massah Ed, he doan tink it so.