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Vac Bubbles


#1

Yo George, When’s the last time you changed the oil in your vac
pump. Grainger sells vac oil at a reasonable price. I do it once
a month (or every 3000 miles!) No, really, change it often.
Depending on the climate where you live, you can suck a lot of
moisture into the pump. The oil gauge is on top and oil floats on
water so you may look at the gauge, see oil and not give it a
thought. You can lengthen the life of your pump significantly
with regular maintenance. Have you timed the gloss-off on your
investment? You may know that you can work up to 1 1/2 mins.
before gloss-off. Use all the vac time you have. What ratio of
water to investment are you using? Some people just mix powder
and water together and hope for the best. But you weigh and
measure closely, right? Pink yes, alcohol yes, plus soap
(surfactant) as the most important ingredient. Try to use your
smaller bell jar so your pump doesn’t work so hard. Also, use
some water under your rubber pad as well on top around the rim of
your bell jar to help seal your vac process. Let me know how you
make out. J.A.


#2
    Also, use some water under your rubber pad as well on
top around the rim of  your bell jar to help seal your vac
process. Let me know how you make out. J.A.

In the dark ages we used Vaseline

Will Rogers never met a lawyer.

Bobert


#3

hi john a.,

shamefully, it was a long time ago that i changed the oil,
longer than the last time i bought debubblizer, i confess. tho i
live in a very dry climate. but i don’t think that the climate
will oil my vacuum pump. do you think the pump is toast or will
flushing it out and changing the oil now do any good? any hope?
this is a ‘fast vac’ 3cfm. i got a different gauge and it
verifies the reading of 26. i have another vac pump that is a
grange 1/4 horse that i got for 25.00 at a pawn. it gets a
reading of 27. i have no idea of the other specs. is one really
supposed to get a reading of 29? sounds like a dumb question but
i was looking thru the grainger catalog and none of their vac
units say they draw more than 27. i know all the jewelry tool
catalogs say they draw 29, sooooo why doesn’t the same units in
the grainger catalog draw 29? it’s late and i’m rambling.

i’ve discovered that the vibrating table is a little too small
for the larger bell jar, so this may be part of my problem. i
can’t test with the smaller bell jar because i lent that out.
i’ll git it back tho.

because of these problems, now i’m carefully weighing out the
investment, tho i thought i could get away with weighing the
water, i don’t think so now. the cc graduate is on the way. i
try for a 40/100 as the satin cast instructions say. i buy the
40 or 50 lb box and throw out any i have left after about 3 mo.

like you said, i religously checked the window on the vacuum
pump looking for water or debris, not even thinking about what
floats on top of what.

what is surfactant? i looked it up in my 20lb dictionary and it
wasn’t in there.

i’m basically a guy who was inspired to start casting because of
problems described in the “crummy castings” thread. now i enjoy
the control of deadlines and mostly enjoy the process. i also
like to know i did the whole thing.

thankyou again for your invaluable advice. i’ll let you know
how things go after i get these things straightened out.

best regards,

geo fox


#4

Both Water and petroleum will out gas into the vac jar. Go to
an Auto supply store and get some heavy duty silicone grease. A
little applied to the lip of the jar will help maintain a seal. A
tube (4 oz.) should last a couple of years. It also won’t cause
the rubber to disintegrate like the vaseline possibly can.

Ed Ward
Ward’s Stone Creations


#5
 Also, use some water under your rubber pad as well on top
around the rim of  your bell jar to help seal your vac process.
Let me know how you make out. J.A.
In the dark ages we used Vaseline

In even darker ages when I was engaged in messing with very low
pressures we had to use a very sticky stuff called High Vacuum
Grease which cost an arm and a knee. You see, Vaseline was too
’runny’ and got slowly pushed under the flange of the bell by the
atmospheric pressure in the course of a day! (see earlier
comments) Cheers,

John Burgess @John_Burgess2