Stain Dipper

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Stain Dipper Machine – Lathe Work

In the Stain Dipper Machine, we have a top pulley which is mounted on a 10mm shaft that is seated in 10x26x8mm bearings.  In the last post on this topic, I showed the pulley holder assembly.  In this post I’ll show the pulley and the final assembly.

Here is the finished pulley, made from a 1″ long by 1.5″ diameter piece of brass.

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Here is the pulley mounted on the top of the machine.  This is a satisfying point in the project because of all the ways this could have been solved, we chose an elegant, smooth, and accurate one.  You can’t buy this specific part anywhere in the world – we designed and made it just for this purpose.

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Here is a picture of tapping the pulley for a M5 set screw.

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This is a picture after the first operation was complete.  Now we need to turn it around in the lathe, recenter it, and finish the other side.

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Here is a picture of the part in the lathe.  Notice the difference in surface finish?  The shiny area is freshly cut.  The dull area was original surface.  The semi-dull area was shiny just an hour before, but oxidization got to it that quickly.

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A view of the spinning 4-jaw chuck and quick change tool post.

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Stain Dipper Machine Top Pulley Assembly

One of the key components in the Stain Dipper Machine is the top pulley assembly.  It is crucial that it normalizes the unspooling location of the cable so it does not put lateral forces on the slider rod below.  To this end, we designed and created 3 components out of UHMW (Ultra High Molecular Weight Polyethylene).  It’s a nice plastic to work with, and super tough.  It cuts like butter but has a lot of strength too.  This is a 10mm hardened shaft with two bearings pressed into the UHMW.

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Here is a picture of the 3D model.  As you can see I haven’t trimmed the shaft yet.

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Stain Dipper Slider Guide

In my last post I had an image of one of the guides and the slider in the background.  The slider is an aluminum extrusion and the guide is 0.75″ thick Oil Filled Nylon.  Nylon is resistant to stain and other chemicals we are using as well as having a low friction coefficient.

Here is a close up of the 3D Assembly taken straight from my computer screen.

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Here is a photograph taken with my phone of the actual part that has been machined and installed.  There is something satisfying about designing something and then making it exactly (within tolerance) to the size and shape you wanted.

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