Step 7: Plastic Sliders
These pieces slide into the top block, as well as over the bottom rods. You'll mostly be using a lathe for this step.
I started with 3/4" teflon, but as I said you can use other plastics. Approximately half the rod needs to be machined do to *just fit* in the holes you've created. When you get close to the right diameter, only machine off about 2/1000" at a time, and check to see if they fit snugly via friction.
Next, you'll need to drill a hole all the way through of the same diameter as the metal rods--3/8" in my case. Again, use a center drill to start with. You may need to drill from both ends to get the length you need.
Next, you'll want to use a reamer to smoothen and enlarge the hole. Reamers are made with very slightly larger diameters than common sizes: a 3/8" drill is 0.3750", and a common reamer size is 0.3760". This is perfect for us since it gives us just enough gap for a smooth slide.
The other half of the rod should be machined down to a smaller diameter; one that fits freely in the hole. Mine ended up as 0.68" diameter; you may need more or less depending on how precise you are with the other measurements. Constantly try sliding the rod down the metal rods to make sure they enter the hole freely.
Last, you'll want to bevel the end so that it is guided down if there is any misalignment at all. If your measurements are perfect, you may not need this, but I did.