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Modified the lid to be an open design. This will allow the skim tube access.
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Originally I attempted to run the tube against the current. This proved dangerous as it required a lot of rigidity and force. After a little experimentation, grinding, and welding, I came up with a first with the current design. It worked but was sloppy, lots of splash.
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After a good nights sleep, I devised a compound bend that was trimmed. The initial sweep is barely noticeable. This worked better but still wasn't right.
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Next I made a very tight bend on the end. This worked really well but the splash was still an issue.
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I decided to flatten the tube. This worked well.
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I then made a steeper bend and flattened it. This worked well. A little mist but no large amounts of spray.
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I did a little trimming and grinding. This tube works mist free. I suspect the sharp entry edge was key.
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Here is a close up of the sharped entry.
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Bored out the clean Lexan lid in preparation for some testing. I needed an additional half inch for the skim tube to clear.
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Mocked up the skim tube on the mill to test the clearances and rotation. This is the resting position.
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The skim tube is rotated 90 degrees to discharge the fluid in the rotor. The clear lid will allow us to see the tube in operation.
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Profiled a handle out of some 0.5" aluminum plate.
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The handle was then drilled, counter bored, and tapped by hand.
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The handle was then sawed with a slitting saw allowing the part to act as a clamp.
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This is the handle installed to the skim tube.
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Dry fit the prototype parts to the machine. This will be used to test the operation with the clear lid. The lower arm is adjustable and is supported by a short length of UHMW.
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Skim tube in the parked position.
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Skim tube in the full discharge position.
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Rotor with clear lid nearly full of water.
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Water being discharged by the skim tube.
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Discharge is going well. Rotor is about half full.
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The discharge is very smooth and quick. The psi of the fluid in the rotor is generally between 40 and 50 psi depending on the specific gravity of the liquid in the rotor.
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Rotor is nearly empty. Note the position of the skim tube.
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Decided to upgrade my machine in the shop for testing. First I had to install the taper. Note how how the shoulder was in this original casting. It has since been raised.
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This is the modified rotor installed and running.
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Parting off the skim tube port that will be installed into the lid.
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The second operation on the skim tube port.
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Modified the lid to accept the skim tube port.
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Pressed the skim tube port into the lid.
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This is the view from the inside.
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This is the skim tube installed and ready to test.
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After using the skim tube to discharge the rotor all that remains is about 1/16" of hard waste. You can see how the skim tube cut a portion of the waste out.
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It's hard to tell from this photo but the waste scrapings came out like a thin ribbon.
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Another photo of the thin layer of remaining waste.
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In preparation for some rotor design changes the center nut needs to be redesigned. This is the first operation.
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After the part is parted off the bar it's flipped around in a collet ready to be machined.
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Second operation completed.
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Next the part is moved to the mill and the hex is completed. Nice action photo.
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The 1/2" (13mm) hex is completed. You can see the before and after parts.
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This is the new nut installed in the rotor.
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Added a pound of corn starch to a slurry and introduced it to the centrifuge.
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Installed the skim tube assembly.
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After discharging the water from the rotor.
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The skim tube cut a slot in the cake but didn't really discharge much of it.
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You can see how dry and firm the cake is.
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The cake can be easily removed from the rotor and dried for further processing.
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This photo shows just how little liquid remains after skimming. Very nice.
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The skim tube requires an actuator adapter. This is the design.
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After the operations on the lathe the stainless steel part is moved to the mill and a square is milled into it.
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The part is then fixtured and counter bored for the screws.
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Two drill operations. One for clearance and a second for the tap are done.
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Next the part is rigid tapped for the screws.
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The part is then slit with a slitting saw.
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The horizontal operations are done.
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The fixture is then flipped upright and the clamp is slit, finishing the part.
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This is the finished adapter/clamp assembly with a scrap piece of tubing.
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