Hi all,
I really liked all of the different way folks have found to
eliminate bubbles in castings. And John B. and other techies,
thanks for the REAL inside dope on this stuff. Now I just wish I
could figure out how to get some of it to get filed in the old
gray matter in such a way as to be findable later when I need
it!!!
We mix with a little electric hand mixer with just ONE MIXER
BLADE in it rather than the 2 that could be used. Much less air
incorporation. CAREFULLY measure both the water and investment,
not relying on the eye for proper consistance. The instructions
on R&R’s ultra vest state (approximate quote)" add WATER TO
INVESTMENT and mix for 2-3 minutes. (I split the difference and
mix for 2 1/2 minutes). I vacuum for 30 seconds AFTER the
investment settles from the “boil”. Pour down the side of the
flask (use RIO’s pink debubblizer in a perfume mister on the wax
early enough so that it is dry by the time I am investing… uses
the debubblizer up slowly but you get a very even coat and a
gallon lasts and lasts… ). Re vacuum for at least 1 minute
after the boil settles (not much boil here as most gas has
already been removed in the first vacuum).
If you had investment in the vacuum lines (when you cleaned
them) you might consider adding some sort of a line filter to the
line going to the vacuum pump. Investment dust will raise heck
with the pump vanes or pistons or valves, deminishing the
capabilities of the pump dramatically, more so the greater the
vacuum.
If the bell is really fitting the table seal, you should be able
to hold a vacuum for a L O N G time but the valve closing
the bell from the rest of the system should be a good one and
between the bell and the pump, meaning, don’t rely on the pump
to hold the vacuum.
I forgot who commented about changing the water/investment ratio
to a bit more water but I think I am going to try it. Sounds
reasonable to me, just be aware of potential investment strength
degridation.
Lastly, R&R has a wonderfully helpful technical support
department so if all else fails, give them a call for some of
their ideas. (800-800-7496)
John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.
PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332
If your’re headed in the right direction,
each step, no matter how small, is getting you closer to your goal.