Ive been working on my own vacuum casting machine, building it up
from parts I can pick up at a decent price. Went to do a final test
run on it today and man did it work great. A little Crest Vacuum pump
I picked up on Ebay a while back for 26 dollars plus shipping sucks !
Anyway, there was one thing I discovered today that I thought may be
handy for any vacuum casting people out here in Orchid land. The
large mat used when you vacuum casting plaster to get the air bubble
out that cost a small fortune from the tool supply house can be
replaced with a much cheaper, and more versatile pad.
Go to you home supply store, I went to Home Depot. Picked up a 4
foot long, 16inch wide roll of Shelf Cover Brand made by WEP
Enterprise Inc shelf liner for wire shelves. Its an Anti-Bacterial
foam so its really dense so the bugs cant get into it. After laying
getting it flat with some boards and a few heavy power tools, I put
it on the casting table, put on the vacuum bell and plugged in the
vacuum pump. This stuff works fantastic! It seals so well you cant
pull the bell off the table while its on, no matter how hard you pull
on it. And I had the table screwed down for the test as I had my
daughters with me today and I didnt want it knocked over and land on
them. I still have to finish the table, this was just a test on the
pump and the way I routed it in, and the matt.
The whole 4 foot length cost less than $10… Now I just need to find
a low cost vacuum gauge and I will have this puppy completed.
I am also in the process of making my own vacuum chamber and found a
vacuum gauge on ebay (UK) for a few quid.
I have also got a product that I think will be suitable for the pad
of my vacuum chamber, although I haven’t tested it yet.
I picked it up for free from a flooring company, a bit of their
offcuts.
It is the rubber flooring used in commercial flooring. I don’t know
how else to describe it, black - 5mm thick and rubber. I am quite
confident it will do the job…
On the same subject I picked up an inline fuel filter (for cars)
from ebay for a couple of quid to act as my inline filter for
catching debris that can ruin the vacuum pump.
Are you planning on just vacuuming your invested flasks - or
actually setting 900 degree flasks on this material while you pull
the vacuum and cast?
If it’s the latter you just might wanna do a test run - outside the
building - to see what’s gonna happen… the silicone rubber pads
that we normally cast on are made to withstand the high heat - your
substitute may not fare so well.
The shelf foam may work for de-bubbling casting investment, but will
it survive a hot casting flask?
This stuff works fantastic! It seals so well you can't pull the
bell off the table while its on, no matter how hard you pull on it.
And I had the table screwed down for the test as I had my daughters
with me today and I didn't want it knocked over and land on them.
If you want to keep students out of the “cookie” jar (i.e. vacuum
bell jar containing precious metals), you pull a vacuum on it before
shutting down the machine. Even if the bell jar leaks back to near
atmosphere, it will still hold. Why? Because 14.7 pounds of air per
square inch is pushing down on it. For one square foot of surface
area, as much as 2100 lbs force is acting on it.
I used to think that glass bell jars had metal cages around them to
protect them from damage, and to make it easy to pick them up. I
later learned that they are primarily for protection of the operator
in case the bell jar collapses. I have never seen one implode, and I
hope I never do. I prefer a stainless steel bell jar with view ports.
If you need an almost free vac gage (donate to Orchid), just email
me off list.
Are you planning on just vacuuming your invested flasks - or
actually setting 900 degree flasks on this material while you pull
the vacuum and cast?
NO
The rubber would probably melt at 100 deg !!! This is just to use as
a vacuum chamber for the investment.
I have just picked up a second hand centrifugal casting machgine, so
I will be casting via that route.
However, a practising goldsmith has told me that he uses a simple
RVT rubber for a seal when vacuum casting. He informs me that it
works very well with the heats involved and again is just pennies to
make.
I can't help it! What is a "quid?" Money, I realize but value in
Euros.... or $.....?
A “quid” is a unit of monetary measurement dealing only in the
British Isles. It’s a slang term for “pounds” or parts of a “pound”
(not sure of this section). A “Pound” is equal to about $2.00 CDN or
$1.76 USF’s…Also a “Pound” is also the main unit of monetary
dealings. Ultra confusing, eh? but not to get confused with pound as
in weight…:>).
Hello Daniel, A great idea for the mat on your vacume machine. Now
all you have to do is go to a cheap auto supply store and get a
vacume guage for about nothing.
I just wanted to take a moment to thank the person that posted about
the shelf liner as a pad for their vacuum table. ( I went through an
upgrade recently and lost the posting I had saved) I have always had
a problem with getting a decent seal on my home made vacuum table.
The pump is a large one and pulls a good 30 inches of mercury in no
time, once it seals. The shelf liner worked as described and since I
cast with a centrifuge I don’t worry about the heat issue on the pad.
Quick and easy seal. Problem solved. Thanks Orchid for teaching an
old dog a new trick.