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On Sun, 2003-04-20 at 22:46, grantfair2001 wrote:

I have a used, surplus, Gast vacuum pump, never used in 25 years,
which I recently fired up to provide air to a "sparger" in a PCB
etchant tank.

I had to clean up the motor a bit so it would turn. At first it did
not output any air to speak of, then, it seemed to kick in after 5 or
10 minutes of running. It has been working ok for about 10 hours of
continuous use, but I would like more air from it.

The motor label states it has carbon vanes. I assume the old vanes are
worn and the cause of the low air output. Does anyone know of a source
for replacement vanes at a cheap price for a pump this old? Or another
fix?

Thanks,

Grant

Greetings

By virtue of your membership in a 'tinkering' kind of group I would
suggest that you open up said pump obtain carbon of a close size and
make the new blades.

Carbon is machinable just use very sharp tools and light cuts!

Darald

Thanks,

Grant

On Mon, 2003-04-21 at 11:56, grantfair2001 wrote:

Hi Darald-

Machine carbon? To a high precision fit?

As Peanuts said to Lucy, you have very high ambitious - for me <g>. I
am sure it would be beyond my skills. I am reluctant to simply take
the pump apart for fear of damaging it. It does work now, although not
as well as I would like. Where are you in Canada? I'm in Toronto; if I
can find the carbon maybe you could demonstrate in your shop?

Has anyone on the list taken one of these pumps apart and know what
steps are involved?

Grant

Greetings

If I had a shop or worked in one where I had access to equipment for
after hours work I would say no problemo!!

I worked in a shop where we made carbon bushings for pump shaft
whatevers. These were done in a size from 1" OD and 3/4" ID to 3.5" OD
and can't remember the ID on that one.

We used HSS tools with a nice sharp edge with a generous radius on the
tool tip (but not too large either just more than for steel more like
that for 660 brass) and kept the cuts light. No pushing things to make
them go fast. Also used a small (3/4") paintbrush on the tool to control
the dust as this makes a mess on the machine. Clean the machine often
and clean very very well after!!

If you do not try you will never learn. Just use very sharp drill bits
and keep the pressure down and the rpms at a good rate but not real
fast. If you can machine to bearing fits and put in an O-ring groove
inside a piece 1" in that is 0.100 wide and 0.100 deep (each side) you
DO know enough to tackle it. Just do not get in a hurry and make sure
you actually have carbon and not graphite that is in the pump!

Darald

Try Duniway Stockroom ( www.duniway.com/ ) for the vanes or re-build
kit. My books are already packed up so I can't look it up for you.

Ken Hunter

--- In VacuumX@..., "grantfair2001" <grant.fair@s...>
wrote:

Does anyone know of a source for replacement vanes at a cheap price
for a pump this old? Or another fix?

Thanks,

Grant

On Tue, 2003-04-22 at 21:16, grantfair2001 wrote:

Hi Darald - thanks for the reply, it is helpful.

For reasons unknown, the Gast pump started putting out lots of air
recently. It has been running non-stop for several days so maybe
something wore into shape, though the thing was old surplus when I
bought it. Anyway - for now it is working just fine!

Grant

Greetings

I am currently working on a vacuum truck and every 8 to 10 running hours
I flush the pump with a 3:1 mixture of diesel and ATF oil. The ratio
could be different in your application because I have problems with
internal grease deposition that you should not have. Check with a Gast
vacuum pump distributor as to recommended practice. This process may not
apply to a high accuracy pump but is used regularly on vacuum trucks in
this area.

The flushing is to lubricate (and clean) the inside of the pump.

Darald

On Fri, 2003-04-25 at 14:01, grantfair2001 wrote:

I phoned a local vacuum pump firm and asked about a solvent to flush a
vacuum pump with carbon vanes. (The pump suggests Loctite Saftey
Solvent which doesn't seem to be made anymore). The lady I spoke to
recommended an automobile product - Brake Kleen.

Would this work for flushing the Gast?

Try 3/4 gallon of diesel with 1 qt of ATF mixed in.

The brake Kleen could be used after this. The diesel mix is a very low
viscosity lubricant.

You could try the diesel mix first and then see how the pump works.

If you are trying for a very very low vacuum then put in some brake
kleen and it will absorb and remove the previous and the inside should
be polished again.

Darald