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Vacuum Chamber Casting Unit (was: re Too much trouble)


<< I have built my own vacuum chamber casting unit. >>

I am interested in how you built your own vacuum chamber casting unit. I
am in the process of setting up my own workshop, and I was planning on
buying an investment vibrator because I really can’ afford a vacuum
investor. However, if there is a way to reasonably build a vacuum investor
I would much rather invest using the vacuum.

Larry Hammons
Cheyenne, Wy

< I am interested in how you built your own vacuum chamber casting unit.

Larry. To build a vacuum investor is easy. Obtain an aluminum plate for
your work surface about 15" square. Place it upon a workbench and drill 4
holes in it. One at each corner, making sure to go through the bench top as
well. Next place 4 springs under the plate to raise it off the surface of
the table. The springs should be directly beneath the holes. Place bolts
through the holes through the springs and on down through the table top.
Place nuts on the end of the bolts under the table top. This is your vacuum
plate. Drill another hole near the edge of the plate on down through the
table again. Use a tap and tap out the hole in the aluminum and screw into
it a pipe extending down below the underside of the table top. You might
have to enlarge the hole in the table for this pipe to allow for some
movement. Go to a local rubber supply house and obtain a piece of pure gum
rubber to place upon the aluminum plate. Find a local air conditioning
supply house and buy a vacuum pump. Mine pulls 6CFM and cost 175.00 That
beats the ones offered in jewelry catalougs for 450.00 that only pull 3CFM.
Also buy a vacuum gauge and a two way valve and some vacuum hose. Connect
the hose to the pipe comming from the aluminum plate. Run it to the 2 way
valve. From the valve run it to the vacuume pump and to the vacuum gauge.
Turn the pump on and place the bell jar (which you still have to buy from
the jewelry supply places to my knowledge) on the rubber plate. You now
have a vacuum investor. Make sure to place a hole in the rubber plate where
the pipe sticks up and you can use a hand held vibrator to help break
bubbles free. The valve will release the vacuum pressure when your done and
the gauge will tell you your vacuum in inches of mercury. Make sure to
release the pump from pressure when done and change the oil when it turns
milkey. That is a sign of moisture in the oil, and will cause the rotary
vanes to rust. You can also run the vacuum line to another plate with a
hole in it and place a silicone pad on top and you will have a table top
casting unit. Or build a chamber and run a line to it for a chamber casting
unit. I used a 9 inch wide steel pipe and capped off one end. I ran the
hose in through the side near the bottom. It took a lot of weilding but the
entire unit is in one mobil cabnet. It cost a total of 275.00 in actual
parts and a lot of scrap steel. If I didn’t explain this very well let me
know. Without visual aids an explanation can often be difficult.
Especially since I know what I want to say and you have no idea what this
thing in my shop looks like. RED