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Secure mount for centrifugal casting machine

Jewelry Discussion
#1

I inherited an old but unused casting (centrifugal, broken-arm type)
machine. It came with just about everything, including a table built
of 2x4s and plywood. The safety wall around it was pretty lame
though, so I bought a metal wash tub (27" diameter) to replace it.
The table it’s on will not do though, it is too lightweight and isn’t
bolted down to anything.

I don’t have room in my workshop to bring it indoors and mount on a
wall-stabilized bench, so it’s outside on a covered patio. I don’t
want to drill into a concrete block wall of a house I’m trying to
sell.

I’m pretty handy, so I’m thinking of making a better base for it.
Any advice on working height, type of base, type and mass of the
object(s) used to keep it from dancing around the patio?

thanks very much,
Kelley Dragon

#2 
I'm pretty handy, so I'm thinking of making a better base for it.
Any advice on working height, type of base, type and mass of the
object(s) used to keep it from dancing around the patio?

build a low box from 3/4 inch plywood or some such. I’d suggest 24
inches square, or whatever seems suited to the size of the washtub.
Assemble with screws and glue, not just nails. Put it on heavy duty
castors so you can move it around. Now fill it with a hundred pounds
of concrete, sand, rocks, etc. Then fit the top surface on, and
mount your tub and machine. By the way, don’t forget, when casting,
to balance the arm of the machine so it doesn’t tear itself apart.
Some vibration is normal, but you don’t want it trying to shake the
whole neighborhood…

#3

Hi Kelly,

The “old school” base for those things was a 55 Gal drum with the
bottom 2/3 full of concrete. (set a mounting plate into the concrete
before it hardens.)

That’ll definitely work, but god help you if you ever have to move
it.

My old one (in storage, damnit) is a 55 gal drum, with a wooden
plate (shielded with .050" aluminum) at the right depth. The
centrifuge is mounted to that.

Underneath the wooden plate is a large plastic drum with a pair of
plastic valve fittings that fit garden hose at top and bottom of the
drum. I just fill it with water, which has several advantages: first,
it’s easy to dump when I need to move the machine, and second it acts
as a sort of tuned mass damper. If the base gets wobbling, frequently
the water will wobble out of synch, such that it actively damps the
vibration. Unintended, but cool. (Water being heavy, I think I recall
figuring out that the 30ish gallons in the tank weighed about 250
pounds. If that doesn’t hold the blinking thing down, you’ve got
bigger problems.)

The way this came about was that I had a plastic drum & container
manufacturer in town with me when I built it. I could get seconds on
their big 55 gal drum liners for dirt cheap, and caulk two of them
together to make a (more or less) sealed water tank for almost
nothing.

Regards,
Brian.

#4

I have a similar situation. First I had to balance the arm then I
added sand bags to the lower platform for the table.

Hope that helps.
Ken Moore
www.kenworx.com

#5

If the working height of the existing table works for you, and it is
sturdy enough, if too light, use some plywood or a few more 2X4 or
2X6 to make a “basket” at the bottom of the legs. You can add sand
bags to that to give you the weight you want. When you are ready to
move, you can empty the sandbags in the garden and refill them at the
new location.

I don't have room in my workshop to bring it indoors and mount on
a wall-stabilized bench, so it's outside on a covered patio. I
don't want to drill into a concrete block wall of a house I'm
trying to sell.

Ron Charlotte – Gainesville, FL

#6

Hey Kelly, get a large heavy plywood panel, get 4 bolts to match the
holes in the caster base. Run the bolts from the underside of the
plywood, make the bolt heads flush, through the caster base and hold
the caster down with wingnuts. Make a dry run see if the plywood is
enough to hold the caster securely, if it jumps a bit then place
weights at the corners. Just make sure the caster clears everything
before you wind it up.

Jim Doherty

#7

I needed to add extra weight to the cabinet on which I bolted my
caster.

Sand bags were too heavy for me to lift, so I got big concrete
building blocks and stacked them up, completely filling the interior
of the cabinet. I got the cabinet at the local thrift shop–ugly, but
real heavy, and very well constructed so that it takes the vibration.
Works for me. Alma

#8

We also have a centrifugal caster built into a wash tub. We have
simply bolted the tub to a plywood board and stand on the board
while it spins to keep everything stable. The working height is not
the best but as we only cast 3-4 times a month this simple solution
works pretty well.

charlie

#9

PS Balance the crucible arm that what weight adjustment is for… at
least on my large centrifugal…

#10

I have a large broken-arm caster in my studio. I’ve mounted in a
corner of the room on a plywood workbench I built for it and other
pieces of heavy equipment. This is pretty easy to do. I had Home
Depot saw a 3/4 in. thick piece of plywood lengthwise into 2 panels.
I screwed a number of 2 x 2 pine strips into my walls to support the
double thick plywood top ( 1 1/2 in. thick!) If you screw your 2 x
2’s into the wall studs, they are incredibly strong. When I move out
of my studio, it will be a small matter to patch the 6 to 8 screw
holes in the wall. After the double thick plywood is screwed onto the
mounted 2 x 2’s, and a small 2 x 2 leg is attached to the one
unsupported end of the workbench, you have one strong workbench
WHICH WILL NOT MOVE at all. I have through-bolted my casting machine
to this workbench, and have absolutely no movement at all when I
cast, no matter how out of balance my machine might be. Steady as a
house, and quite cheap and easy to built.

When in doubt, screw it to the wall, I say!

Jay Whaley

#11

You mention the centrifuge “dancing around” It should not do that.
Properly operated and in good condition the centrifuge might show
minimal vibration. There should be a threaded weight on the arm
which is used to balance the arm for the weight of the flask and the
investment. Sometimes there will be a slight single jolt as the arm
straightens but certainly not enough to jerk the machine off a
table. As for a containment system, I have a centrifuge mounted
inside the casement of an old top loading washing machine. The whole
unit is on wheels and light enough to be easily moved around for
storage, etc. When not in use for casting, the enclosure serves as
storage for extra crucibles and flasks. This works very well for me.

Gerald Vaughan